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Vll Nitrogen Cycle See diagrams in Textbook and P pg 13 Learn this well A Nitrogen Fixation N w 4 0 1 F 1 an N 9 The evolution of the atmosphere makes understandable why life on our planet seems to be starving for nitrogen amidst an abundance of nitrogen as very few organisms can fix that is reduce nitrogenquot N2 is a rather inert gas Most biological nitrogen is reduced little oxidized Because originally nitrogen was available as NH3 with an energy source NH3 could readily form organic compounds with CH4 and carbohydrates Later Just as an energy crisis was resolved by photosynthesis there would have been a nitrogen crisis which was resolved by evolution of the nitrogenefixing ability which occurs under nearly anaerobic conditions in cells Why so difficult Examine process made N2 quotgt160 Kcal amp nitrogenasegtN N tremendous activation energy N H quotgt13K NH3 requires input 147 Kcal to form reduced nitrogen This ability to fix nitrogen is found only among prokaryotes a Few soil bacteria Azotobacteriaceae Aerobic Clostridium Anaerobic and certain others including Desulfovibrio amp photosynthetic purple bacteria b Some blue green algae Cyanobacteria quotTrichodesmium Anabaena Gleotrichia and some lichens that have cyanobacteria symbionts c Rhizobium a bacterium that is mutualistic on legumes and lives in root nodules represents a short cut to plants Other such Nefixation symbioses are known with certain epiphytes and woody plants such as Cycads Alders Gingkos Casuarina Myrica Araucaria In all cases studied nitrogenase requires Molybdenum Acid conditions inhibits reaction Moreover nitrogen fixation requires anaerobic conditions thus heterocysts in blueegreen which are special anaerobic cells for Nefixation Why not intracelluar symbioses in eukaryotes After all evidence is strong that eukaryotes evolved mitochondria from a symbiosis with bacteria that had the enzymes for aerobic respiration However respiration requires oxygen which maybe incompatible with anaerobic Nefixation Or perhaps it s a accident of evolutionary history Never assume that evolution would occur Quantity of Fixation see diagram pg 13 Very small amount forms from direct oxidation to nitrate during electrical storms amp volcanic eruptions together estimated at less than 35 mgmZyear in biosphere Less as some in rain from aerosols off the sea and Nefixation by atmospheric bacteria in thunderheads Most biological nitrogen fixation is on land in soil up to 20 gmmZyearat best Average on land about 1 gmmZyear The rapid turnover time for nitrogen in the active pool cycle is only 100 years overall one year on land In water much slower in oceans 2500 years The oceans are deep and dilute the fixed nitrogen greatly and nutrient levels low Inactive pool cycle for Nitrogen Gas in the atmosphere Overall turnovertime is about 07 million years 4 A major mystery 77 we cannot yet account for the nitrate and ammonia levels in the sea by presence of nitrogen fixers Virtually nothing is known Only nitrogen7fixing cyanobacterium genus Trichodesium lives in the sea Dichothrix fucicola a cyanobacterium that is epiphytic on Sargassum can fix 35 mg of N per meter square per year Evidence shows oceanic fixed N comes from terrestrial7FW input of nitrates 7 Uptake through food chains consumers 77gt decomposers uptake by microbes important to return N to the active pool in sea 8 Nitrogen easily fixed by Industry to form fertilizers by the Haber Reaction But this costs money and promotes excessive nitrates causing eutrophication excessive growth of algae in fresh water Ammonification Bacteria Actinomycetes fungi plants can burn ammonia for energy But animals cannot and must excrete nitrogen as ammonia urea or uric acid Ammonia poisonous urea soluble uric acid insoluble Mammals cannot make uric acid so have problems conserving water and tend to suffer from gout caused by uric acid in the diet crystallizing in the lowerjoints 2 ln marine environments because of relatively low bacterial counts ammonia is an important source of nitrogen for phytoplankton 3 ln soil amp freshwater ammonia is not utilized directly in any significant amount by plants and algae because being reduced it is energy and is oxidized by microbes D Nitrification 77 Mostly in the soil oxidation of ammonia CD 0 l Nitrite Bacteria 7 Nitrosomonas NH3 77gt N02 66 Kilocalories fermentation of glucose by comparison yields 36 Kcal Z Nitrate Bacteria 7 Nitrobacter N02 77gt N03 175 Kcal a tiny yield of energy lnteresting Rule 15 Kcalmole needed to make a living off a reaction 77 so barely enough the microbe must process a lot of nitrites to grow 3 Nitrosocystis oceanus NH3 7gt N03 very low levels 7 not enough to account for N03 levels suggests terrestrial origin of nitrates and uptake of ammonia E Nitrates taken up by plant roots and algae cells While NH44r ions get trapped on clay7humus micelles but available to bacteria N0377 moves freely and is readily lost into ground water and into freshwater F Denitrification 7 7Anaerobes such as Pseudomonas denitrificans convert N03quot Glucose 77gt N2 570 Kcal which is a good yield compared to aerobic respiration yield of 02 Glucose 686 Kcal G Problems nitrates very soluble so lost to water readily l Easily leached from soil especially plowing fields which promotes rain run off and soil erosion which all promote loss of soluble nitrates Z Nitrates run off to sea and are ultimately lost into sediments 3 Artificial Fertilizers besides costing can be dangerous at high levels and create ecological backlashes to technological quick fixes 4 Nitrate run off 7gt Eutrophication in fresh water and loss of OZ BOD Vlll 0 1 gt909 w 4 0 1 CD 1 00 A human problem is methaemoglobinemia In milk amp water in stomach N03 7gt N02 which binds with hemoglobin causing nitrogen anemia Can be a serious problem with baby formulas Nitrites in preserved food such as in meat is a carcinogen Nitrites and nitrates 7gt NO breaks down 03 in the atmosphere Nitrites Organic pollution in the air and sunlight 7gt PAN smog peroxyacytinitrates which are very poisonous Sulfur and Iron Cycle A Sulfur Cycle See diagram pg 14 class notes do not need to memorize l Sulfur was though to be of little natural importance because of its high abundance although acid rain from sulfuric acid is dangerous 2 However 2 or 3 times as much sulfur is washed to sea as is available in rocks and in soil on the land therefore there is cycling of S between sea amp land Recently shown that organisms in the sea especially algae produce dimethyl sulfide that escapes into the atmosphere and oxidizes into methane sulphonic acid which forms condensation nuclei that promotes rain some of which falls on land completing the cycle of sulfur back to land The fresh smell of the sea is dimethyl sulfide Sulfur chemistry is complex as it exists in many oxidation states 72 to 4 It is used by organisms in the reduced state as in certain amino acids coenzymes and other compounds H2S is produced after an organism s death under anaerobic conditions that is SHgt H2S which is oxidized under aerobic conditionsgtS02 in few hours Also SH mgtS02 combustion S02 H20 7gt H2S04 acid rain Man the human volcano by smelting sulfide ores by burning fossil oil and coal and the vegetation produces excessive SOZ This combines with water to form large quantities of H2S04 sulfuric acid that rains down Too much sulfuric acid is very toxic a This can leave create local desertelike bare soil areas by killing vegetation as happened in Copper Basin Tennessee a manemade desert area b more widespread acid rain becomes too acid and kills acid sensitive organisms in lakes and forests See P l4bel4f Bacteria also burn H2S and produce ultimately more sulfuric acid a H2S 02 Beggiatoa 7gt S0 H20 ATPn Bright yellow microbe b Thiobacillus cool and Sulfolobus hot springs burn S0 02mgtS04quot Primitive photosynthetic anaerobic bacteria use bacteriochlorophyll to split H from H2S which is much easier chemically than splitting water a green sulfur bacteria H2S C02gtsugar S b Purple bacteria H2S COZgt CH20n sugar ZHJr S04quot and also some species drive SDgt S04quot ATP Next Thiobacillus thioparus carries out denitrification using N03 to burn HZS Also Desulfovibrio desulphuricans reduces the sulfate for oxidation 9 End result of all these microbial interactions is to produce acid anaerobic conditions in the sediments See P pgl4a 9 Function 7 Cycling of sulfur is closely tied to the cycling of metals and phosphates in that acid anaerobic conditions permits their solubility IX Iron Cycle Sulfurelron Cycle diagram Other metals chemically behave similar to iron and have sedimentary cycles with no gas phase Despite the abundance of iron it is a micronutrient in its availability to life 1 Note that in aerobic conditions FeZSg ferric sulfide and Fe2SO43 ferric sulfate are insoluble not available to organisms oxidizing conditions in both acid or alkaline conditions 2 Under anaerobic reducing conditions FeS ferrous sulfide and Fe2SO4 ferrous sulfate are again insoluble in neutral to alkaline conditions 3 Only under acid anaerobic conditions are the ferrous compounds soluble 4 Very important is that ferrous sulfate is the energy source for chemosynthetic iron bacteria This happens in the oxidizing border line between aerobic and anaerobic conditions FeJr 7777 gt FeJr ATP 5 Because ferric sulfate is insoluble the iron bacteria form FeJr gt Fe0H3 a colloid to get rid of it and so makes Fe available to the aerobic organisms In time the iron hydroxide turns into ferric oxide which is called bog iron 6 This explains the formation of enormous iron ore beds that occurred about 18 billion years ago when little oxygen present and bacteria oxidized ferrous 7 More and more we are discovering the surprising roles that bacteria play in ore formation in the sea and deep in the earth X Phosphorus Text pg 5207521 5327533 1 There is no gas phase of phosphorus so therefore like the above metals it s a sedimentary cycle and is readily lost to the sediments as most compounds of phosphorus are insoluble It is therefore the only nutrient that is present in micronutrient amounts but needed in macronutrient quantities Z Necessary for high energy bonds ATP P7P in the biochemistry of all life 3 While almost all its chemical compounds are insoluble under acid anaerobic conditions in the presence of ferrous ions phosphates go into solution and enter into the biological cycle where it is cycled as organic P Xl Food Chain Concentration Effects A biomagnification 1 As energy flows similarly nutrients move through food chains and trophic levels but are cycled back into inorganic compounds that are taken up by the biocoenosis esp plants 2 Some inorganics are cycled rapidly as metabolites in the ecosystem especially the gas phase nutrientse 02 C02 H20 H28 804 NH3 not N2 3 Some nutrients like many of the trace metals are concentrated by direct uptake and through the dynamics of food chains These together drive biomagnification of a beneficial sort as with phosphorus 4 N 4 4 Certain other chemicals are not metabolized but are passively even accidentally taken up into food chains but become concentrated If the chemical is poisonous this can lead to deadly biological magnification This is creating great problems to man because first we are progressively more and more at the receiving end of energy flow through food chain and second with our technology we are progressively making and dumping more and more strange chemicals into the environment chemicals bad enough without biomagnification to compound the effects Poisonous chemicals affected by biomagnification The most deadly are compounds that are as follows a Toxic in higher concentrationscan get at low concentrations b Nonbiodegradable cannot be broken down to detoxify c Fat solublequot get stored in fat and out of the way of detoxifying enzymes lnsecticides Many kinds chlorinated hydrocarbon DDT a good example P 15 a Remember these are biocides universal poisons especially for animals Many like DDT are nerve poisons and animal synapses are chemically much the same Many degrade slowly especially DDT and are nonbiodegradable we all contain DDT in whole world Most water soluble but fat soluble 7 absorbed on particle of detritus Table P 15 shows after use for mosquito control the concentration of DDT increased through the food chain Birds especially suffered badly as DDT poisoning caused fragile egg shells Top carnivores like hawks really took a beating Incidentally the use in USA not the manufacture of DDT banned in US gets into enzyme active sites fouls up their functions a Serious problems in paints metal alloys in gasoline etc b lmplicated in the fall of the Roman Empire as the upper ruling class used lead pots plates plumbing lead pigments for paint amp adornment c Lead is a nerve poison carcinogen causes birth defects d No wonder Nero fiddled while Rome burned 53 CL rum Mercury Hg similar to Lead in its poisonous effects Chemists thought no problem with liquid Hg because it was nonereactive nonsoluble in water a Minamata Bay Japan showed the lack of attention to life Factory used Hg b Microbes detoxified Hg making methyl mercury soluble into food chain to Fish to people neurological damage and worse embryological defectsquot flipper childrenhorrible sight seen at Minamata Bay c Known as the Mad Hatters39 Disease Alice through the Looking Glass because hatters used Hg to form flat brims on hats favored in middle ages d Be careful of swordfish because it s always high in Hg Be careful with all fish Environmental pollution a huge problem Oil spills PCB Polychlorinated biphenyl radionuclides all our waste dumps of poisonous dangerous chemicalsquot who knows what we are doing to ourselves Latest are sex hormone mimics Community Ecology 11 Ecological Successions I Introduction A Old Classical Field of Ecology 1 Early observation of the predictability of ecological successions by Kerner 1863 in Danube Basin and Hult 1885 in Finland as summarized by Warming 1895 were important in the development of ecology as a science N The study of successions became a dominant theme in plant ecology especially in North America because of the pattern of exploitative agriculture where farmers moved on after wearing out the soil of their farms Consequently patterns of ecological successions were everywhere to be studied E While most of the discussion here emphasizes terrestrial plant ecology successions occur every where as shown in Smiths Figs 212 216 2111 2113 2118 B Clementsian School 1 Started with the work of Cowles 1899 of the University of Chicago on Lake Michigan at what is now called the Indiana Dunes Park and National Sea Shore At this location are an interesting series of dunes and ponds a O D Cowles discovered that the dunes and ponds closest to Lake Michigan were the youngest The dunes and pond furthest away form the Lake were the oldest The ecological succession starting with the ponds lling in going from oligotrophic to eutrophic to wetland marshes to swamps to wet forest and then to the Beechmaple climax characteristic of the area At the same time the dunes were stabilized by plants first grasses then shrubs then OakHickory and nally the BeechMaple Climax community This means different physical starting points converged on the same climax BeechMaple Forest 2 Clements used Cowles39s work as the basis for his organismal superorganism theory of the community 7 Communities develop like organisms Plant Successions 1916 was written by Clements in support of his holistic view 3 This research was largely American in re ection of the pioneer exploration and recovery of farmland by forest as farmers pushed westward 4 Gleason 1926 was very skeptical of this view as was discussed earlier 11 Classical terminology and concepts A Climax 7 was de ned by Clements as an enduring natural community in equilibrium with climate 1 Integrated with the superorganism paradigm of Clements 7 he developed the idea as a fundamental ecological process 2 This concept of the climax was based on longterm adaptations of communities to climate Clements 1936 Nature and Structure of the Climax 3 As we earlier discussed Whittaker proposed that the climax should be operationally defined as selfsustaining enduring end point of succession B Sere 7 A Complete Ecological Succession 1 Pioneer earliest invaders 7gt seral stages 7 gtclimax This is a sere 2 Ecesis is successful colonization growth and reproduction by a species in a succession 3 Associes are temporary successional communities as defined by Clements 4 Subclimax is a long lasting usually a forest successional seral stage 5 Convergence of xerarch seres and hydrarch seres in the Indiana dunes area led to same climatic climax which led Clements to believe this validated his superorganism concept of the climax as being the community adapted to the climate 6 The succession started with a disturbance that results in a nudation the elimination of the original community C Primary Succession See Smiths Figs 216219 1 Natural bare areas rock lava sand water7complete nudation 2 Slow succession occurring through physical and biological processes a Physical changes 7 Allogenic changes 7 create soil profile b Biological changes 7 Autogenic changes 7 changes in biological community D Secondary Successions l Climax vegetation destroyed by man or nature 7 fire hurricanes etc but more usually in the USA through cutting of the forest for agriculture 2 Because the soil was already there there is a rapid return to climax from fallow eld mostly by autogenic not allogenic changes 3 Fugitive species have a hit and run adaptation to rapid dispersal and ecesis especially adapted to the early succession stages but cannot compete later in the succession 4 Billings 1938 and Keever 1950 in North Carolina carefully studied the secondary successions and came up with the following pattern of succession common in the southern coast plain of the USA Crab grass weeds one year9 Horseweed field two years9 Aster Composite stage 3 yrs9 sedges 5 to 15 yrs9 Pine forest 50 to 150 yrs 9 Oaks E Modifiers of climax l Sereclimax 7 longpersisting successional stage due to some interrupting or slowing fate like poor soil or pine barrens stuck in succession to Clements these are merely taking a long time to provide the allogenic changes that allow the climatic climax to establish itself 2 Subclimax 7 longpersisting forest stage before final forest climax 3 Disclimax 7 A community prevented from going to climax by an interfering factor like fire overgrazing ie a bad apparent climax F Climax reconsidered l Monoclimax adapted to the climate was Clements s concept This is not far from our earlier discussions of the relationship in terrestrial ecology between the formations climate and the soil His view was extremely long in perspective he saw mountains being eroded down and many communities as in mountains were only associations on their way to the ultimate climatic climax 2 Some ecoogists as Tansley conceived of the Polyclimax 7 that there were many other possibilities for the climax based on other physical conditions than climate and of course as we discussed earlier Gleason threw the climax idea out along with the superorganism thinking that all there were are individual organisms all else were imaginary even the polyclimax 3 Climax pattern theory ecoclines continua of Whittaker As discussed Whittaker saw the world in terms of varying environmental parameters and that species were adapted to conditions along the gradients However some species that are dominants determine as a keystone species the ecology of a community so these species have great importance Whittaker then de nes the climax as a quot that endures and replaces itself 4 Whittaker would say then that re as a natural factor can determine the climax for many communities All the grassland formations the chaparral and many coniferous forests such as the Piney Woods of East Texas and the Gulf coast require fire and are therefore pyroclimaxes Some pines in the west even have cones that open only after a fire Often one sees a forest of the same age trees that all started after a fire 5 Grazing in grasslands is similarly tolerated by grasses for the same reason as grasses grow from their bases not the apex Thus fire and grazing work together to maintain the grassland biome 6 Bormann and Likens noted that because trees eventually die and fall creating an opening and opportunity for other plants to enter proposed that many if not all climaxes are actually better called shifting mosaic steady state climaxes In MapleBeech Forest the dominant climax community in much of northeastern North America maple seedlings tend to grow under Beeches and the beech seedlings tend to grow under Maples a reciprocal replacement 7 Extreme age an important strategy w very few old growth forests left 7 Douglas fir 450 1000 years old 7 is replaced by Western Hemlock and silver firnormous trees with huge biomass A unique fauna including the spotted owl tree vole etc have endured to live here in this special ancient forest 8 Even Sequoia sempervirens the coast redwood and Sequoiadendron giganteum the Big Tree are fire climax forests and require open sunny areas for the regeneration of their seedlings and use their great longevity to produce seeds over a long time toward the time that conditions will be advantageous for their seedlings to survive in the sun after a fire Here age and fire resistance operate together as a strategy for existence 9 Edaphic climaxes are based on soil in uences The quotLost Pinesquot of Bastrop County are a good example They are adapted to sandy soils while the grasses are adapted to clayey soils of the black land prairiesboth are fire climaxes 10 Plagioclimaxes are communities maintained by man and his grazing animals Many parts of the world have been usedor misused by man for so long that we do not know what is the original or expected climax vegetation ll Deserti cation 7 reverses primary succession 7 loss of water holding ability of the soil changes the climax through human interference 7 this is a very serious problem Often the plagioclimaX is the consequence of deserti cation Roman roads leading out into the desert in North Africa give testimony to the destructive effect of Mankind North Africa was the granary of Rome 12 Climatic Change Changes in climate since the Pleistocene and ongoing changes causes changes in the prevailing climax as revealed by palynology and studies now show the advance of warmadapted species and the retreat northward of coldadapted species in probable response to global warming G Succession causes as suggested by Egler 1954 l Ecesis establishment and colonization of propagates in the succession is basic to the progressive changes in organisms present in the successions 2 Relay Floristic and faunistics 7 one seral stage gives way to another progressively like a relay race each species passing on the baton This is based on the plants modifying the environment allogenically allowing later successional plants to come in and replace the earlier stages This corresponds to Primary Successions 3 Initial Floristic and faunistics C0mp0siti0n7Here all the plants start out together in terms of propagules7 firstest with mostest starts the succession and the later plants come in and replace the earlier plants by competition This is basically the secondary succession of Clements H Succession Models of Connell and Slatyer 1977 l Facilitation model the autogenic changes brought about by the earlier stages help later successional plants to take over and is similar to the oristic relay 2 Inhibition model The first invaders render the community less suitable for latter succession slows succession by inhibition but the longer lived plants out compete eventually the early succession plants This is somewhat similar to the oristic composition mode 3 Tolerance model Here the plants that are present have no effect on later succession plants there is no facilitation or inhibition as such the most tolerant species win out in this competition 4 All of these theories involve changes allogenic and autogenic and all are restatements in various ways of the original Clementsian ideas to make them more reductionist less holistic in the sense of Clements s superorganism While much of the emphasis is on plants as they create the biomass of the community in terrestrial systems successions greatly affect the animals too as seen in Smiths Fig 2119 where different animal species live in different stages ofthe succession Many species are edge species Others are interior species and only live in the old growth forest Others require both 6 Replacement in successions Disturbances Organisms have life spans thus constant continuous replacement occurs as in a forest canopy the shifting mosaic patterns of the climax forests as emphasized by Bormann and Likens 7 Cyclic Succession a Tundra 69 Taiga trees shade the soil permafrost rises trees fall over through lack of soil for roots the drunken forest the tundra replaces it lets sunlight in to melt the permafrost and again the trees enter b Cycles of intermittent ponds and oldfield moss and lichens show this cycling of communities see Fig 2114 in Smiths 8 Some ecosystems are maintained by continual pulselike disturbances such as the intertidal environments where the tides and storms continually disturb the coastal environments Figs 211121 13 in Smiths or in wetdry climates where a forest in the dry season becomes a varzea swamp during the rainy season 9 Disturbances 9 perturbations that is temporary changes in the biota a Fires led to special fireadapted communities that can handle the fire disturbances with the least perturbations especially of surface fires b Hurricanes can lay level very large areas of forest c Flooding can kill large areas of forest and promote special ood forests Animals and man can dam streams and ood the riparian vegetation causing it to change wetland vegetation d Severe drought can cause great damage killing vegetation and promoting fire in forests that do not normally burn e Defoliating insects can cause the dead of large areas of forest by exhausting the energy reserves of the plants f Very large animals such as elephants in Africa can destroy woodland by literally uprooting the trees allowing grass to spread which then maintains itself through fire and grazing see Smiths Fig 23232324 g Man s activities agriculture mining lumbering can cause great disturbances h The repair of these perturbations occurs through ecological successions small and large is a natural process 10 Restoration Ecology is a branch of applied ecology that seeks to help an ecosystem recover from great perturbation usually those caused by man In the cases of plagioclimaxes this can be a difficult task and is often the first step in trying to save endangered species as it is often the very ecosystem that is endangered Successions are an important part of Landscape Ecology which studies how ecosystems interact and how man affects landscapes and much of the affects are through disturbing natural communities establishing plagioclimaxes agroecosystems fragmenting communities creating ecotones and patches See Discussion in Smiths Chapter 23 H H Fluctuations in Nature can be cyclic bringing about regular perturbations in the communities H N a Water table changes can bring about changes because plants differ in their ability to tolerate watersaturated soil This can change with rise and fall of the water table with changes in the rainfall b Climatic shifts appear to be normal so the idea of ancient communities that have existed since the Cretaceous are probably false and communities even in the tropics have always had to adapt to such changes and disturbances although the climatic ones tend to very slow acting allowing time for communities to either adapt or migrate 13 Frequency of disturbances important a Occasional small ones are easier to handle and are less perturbing than ones that happen so frequently as to prevent the restoration of the community through the healing of an ecological succession This is especially true of forest fires in the west where frequent small fires are much less destructive than large fires See Smiths Figs 23172118 5quot J Stability 1 Local 7 small perturbations in the community re ecting changes basically local such as a small fire or a ood along a stream Ecological Successions heal these quickly 2 Global 7 largescale disturbances that bring about very large perturbations from which it may be difficult to restore community equilibrium Some of the disturbances of man can fall in this category 3 Resistance measures the amount of perturbation resulting from a disturbance a The community with resistance has the resources to withstand the disturbance and maintain itself b This is characteristic of communities adapted to relatively nonstressful environments in which disturbances are minor of local impact c However such communities are often highly fragile and cannot handle major or global disturbance Remember communities are the consequence of natural selection on the constituent species and disturbance by man can be so great as to overwhelm the existing resistance shattering the ecosystem 4 Resilience is the ability to return to original conditions a Although the perturbation may be great the community bounces back readily even when the resistance is low as in many aquatic communities b Temperate communities normally encounter large disturbances and are consequently characterized by great resilience Natural selection on the constituent species would be for such adaptations c That translates into resilience against even great perturbations caused by man in temperate environments contrasting with the fragility of most tropical communities III Processes and trends of successions See Odum on page 23 in class notes Smith unduly casts doubt on several of the generalizations of Odum which are based primarily on secondary successions A Species turnover basically goes from r selected species to K selected species 1 Rapid ecesis 9 slow ecesis New communities exploiting the pioneer situation need to establish quickly for the environment can be very short lived in secondary successions 2 High dispersal capabilities 7gt low dispersal capabilities Usually the nudations places devoid of organisms are scattered here and there and to get to them takes considerable ability for dispersal while the climax community is widespread often everywhere so the only need to disperse is for finding a host plants insects or to 3 Shade intolerance gtShade tolerance Larger dominant plant species overtop early successional plants A vertical strati cation of species occurs in the forest with reference to tolerance of low light intensity 4 Short lived plantsigtlong lived plants which are dominants that overgrow the early successional plants which are usually shade intolerant 5 Small seeds 7 gtlarge seeds The more endosperm present the more energy available to lift leaves to the sunlight and roots to grow into the ground 6 Low 1 quotquot igthigh I quotquot Early 39 39 organisms are r selected in adaptation to a temporary environment Late successional climax communities are there for the long haul and are Kselected for survival so competition is great 7 Defense mechanisms against grazers and browsers of plants increase from early to late successional stages biochemical diversity increases 8 Animal grazers change from low host specificity to high speci city in response to the poisonous defense mechanisms of plants of the climax B Species composition and interactions 1 Increase in diversity overall occurs through the succession although this is obscured by the large size of the trees in the climax and the very small size of the consumers insects and the microbial life the fungi and bacteria that attack detritus and the tiny size of the feeders on microbial life 2 Dominance becomes shared by many species This is especially true of tropical forests and the chaparral in the temperate especially boreal forest number of tree species is usually low in the climax 3 Ecological niches become more specific longterm species associations develop in the climax 4 More host plants more places to live in vertical strati cation of the climax as in the tropical rain forests leads to greater species richness 5 Symbioses become more richly developed more time to develop relationships such as mycorrhizae in forest plants The larger biomass gives more places for other organisms 6 Species abundances stable 7 more resistant to change in the climax as the species are mostly controlled by densitydependent factors of Kselection C Energy and nutrients 1 In early stages community primary productivity P GPP gt Community R 9 climax P R of the whole community 2 High maintenance costs on all that biomass higher gross PP less net PP available to the higher trophic levels Moreover plants use energy resources to create their defenses against herbivore grazers 3 Shift from grazing to detritus food chains because animals restricted by cellulose and lignins in plants as they become progressively larger and more woody through the protection and support of the biomass mentioned above 4 Detritus as humus modi es the soil improving it which is an important factor in succession in promoting the ecesis of later larger plants 5 Early successions have open nutrient cyclingigt closed nutrient cycling that is from nutrients in the soil to nutrients released from the biomass of detritus 6 Little nutrients stored in the low biomass of the early succession to having most of the nutrients locked up in biomass of the forest 7 Development of symbiosis to enhance uptake and recycling of nutrients 8 Results in a very low output or loss of nutrients from the climax community especially of tropical rainforests 9 Organisms are adapted for the long term in terms of energy and nutrients while pioneers shortterm rapid competition for quick growth and a place in sun D Man and succession 1 Consider that in agroecosystems net production goes to human consumption 2 There is high net productivity in early successional stages a This means there is rapid growth in biomass as maintenance costs are low because the biomass ofplants is small in the early succession b Rapid net productivity little investment in 7 defense mechanisms cellulose lignin and nutrient conservation c Reliance on nutrients already easily available an open nutrient cycling makes early successional plants amenable to using fertilizer 3 Humans eat soft herbs and nonpoisonous seeds 4 Both are characteristic of plants of early successional stages often the food plants are closely related to the weeds in the garden 5 Humans have genetically tailored the crop plants a To pour energy into net of seeds and soft tissues that can we eat b Also this tends to reduce the plant s ability to compete and protect itself leading to plants that cannot grow in nature and we must protect our plants from the herbivores as we have bred out of them resistance so we can more readily eat them 6 Even in forest plantations 7 subclimaX of Piney Woods more economical crop 7 few species rapid growth good harvest of lumber compared to the species rich hardwood climax of angiospermous trees 7 Man must therefore invest much energy an energy subsidy of fossil fuels as was discussed under primary productivity E To maintain early successional stages goes against the succession Fquot This is why we must plow and harrow the soil to create a nudation O Plant in monoculture the edible plants and seeds for efficient harvests 3 1 To protect them against pests use pesticides and fungicides D To eliminate the competing weeds use herbicides IV Paleosuccessions A Climatic change in the Cenozoic period 1 In the early Cenozoic about 60 million years ago when the world was warmer than now an Arctotertiary forest covered Northern Eurasia and North America It was composed of a speciesrich mixture of angiosperms and conifers of similar overall species composition N Southern North America was covered by a Neotropical Tertiary forest E Through the Cenozoic the past 60 million years the climate has progressively overall changed to a cooler drier climate and mountain building further modified the climate drastically 4 The Neotropical Tertiary forest was driven south to Central America The Arctotertiary forest was broken up and modified in different areas V39 A new ora the Madrotertiary forest arose in the drier areas of the Mexican Plateau and southwestern USA 0 Further cooling led to the Pleistocene epoch in which there were cyclic glaciations at least four big glaciations which drove the northern forest south in both North America and Eurasia modifying the forest greatly I Because the Mediterranean Ocean stood in the way and transverse mountains of Europe spawned glaciers the European sector suffered great extinctions of the Arctotertiary Forest B Plant fossils document these changes 1 The most important fossils are pollen grains of the science of Palynology 2 When they fell into dystrophic lakes and bogs the acid conditions preserved the pollen grains which allowed a sequential record to be laid down which documented the changes in the vegetation over time 3 Palynology reveals paleosuccessions of changes in plant communities which documents the drastic climatic changes that has occurred see Fig 2120 in Smiths 4 Shows that during the Pleistocene the tropics were strongly affected in that when the ice sheets were at there maximum the equatorial area dehydrated and the savannas spread at the expense ofthe forest see Figs 2121 to 2127 in Smiths UI The wet tropical forests fragmented into refugia and it is reasonable to use this fragmentation to explain the forces of geographical isolation that would contribute to creating the high numbers of species in the tropical forests 6 During interglacials and some were warmer than the present one the rainfall increased in the tropics resulting in pluvial periods 7 During times of high glaciations in contrast the temperate deserts became moist a different kind of pluvial Great Salt Lake is a remnant of the huge Lake Bonneville that formed during the most recent glaciation the Wisconsin 8 Since the last glaciation the climate has been progressively changing and even the last glaciation was only 12000 years ago It s wrong then to think that any of the ecosystems of the world have lasted for millions of years and communities have been undergoing continual change for a long time but this is relatively slow change not the rapid changes that Mankind is bringing about today C Further back in time in the Mesozoic and the Paleozoic 230 and 600 millions of years ago palaeoecological extrapolations can be made see Table 211 l Palaeoecology can be most successfully applied to marine environments which have fine records because these are primarily depositional environments favorable for preserving fossils especially of mollusks 2 By comparing modern conditions and organisms to those of the past good extrapolations can be made about palaeoclimates and past ecosystems 3 Furthermore geology can now age the sea bottom rocks and measure the magnetic polarity in rocks of land and sea and so tell where a continent or part of a continent was in space and time Competition 1 Introduction A Recall that each particular biocoenosis that is the biological community of an ecosystem is found in a particular biotope or community habitat and within that ecosystem 1 Each species has its own particular role that is its ecological niche which together its habitat comprises its ecotope that is the entire ecology of the species 2 We left it at this and I promised to return to this statement later when we discuss population ecology B Competition 7 a striving between organisms for some resource 1 As the genetic and evolutionary unit is the population competition should be understood in terms of populations whether of sexual or asexual species Darwin long ago observed that systematic or morphological similarity generally indicated a degree of competition 2 Two Types of Competition a Intraspeci c competition Fierce competition between individuals of a species whose outcome is natural selection Recall Densitydependent competition varies with density to K b Interspeci c competition A set of species after a resource is a Guild Root while a taxocene Hutchinson is a taxon with similar ecology which can be an ecological guild as well 3 Exploitative or Scramble competition a Species utilize same resource in short supply and deny use by the other species through that use not by any contesting or aggressive behavior b Note Must be a resource in short supply or contested For super abundant resources like oxygen in terrestrial environment or water in aquatic environment there s no competition c Need not see hear or sense each other to compete Nocturnal and diurnal animal compete if a resource say food is in short supply but do not contest each other at the same time 4 Interference competition aggressive contest over a resource that interferes with the access to the resource by another species 11 Theory of Competition A Earlier stressed that each species has unique ecotope habitat and niche not shared with other species in the same ecosystem why B First consider Theory of Competition then evidence for it 1 Theory by Lotka USA1925 and Volterra Italy1926 dN1 dt r1N1 K1 N1K1 0cN2 sz dt erz K2 NzKz N1 0c is the degree or coefficient to which the exploitation of food resources by another species species 2 interferes and impacts with species 1 l is the degree or coefficient of interference by species 1 on species 2 N If two species are in the same niche then the carrying capacities must be the same in terms of resources K1Kz E The species with the faster rate of increase r will eliminate the other species and win the competition assuming 0c 5 4 If r1 r2 then the degree of interference the competition coefficients at and 5 determines which species would win 5 If r1 r2 and the competition coefficients are equal 0c 5 chance then determines the outcome 6 The LotkaVolterra equations do predict a stable point where the species populations may coexist fig 141 in Smiths based on the effect of in aspecz39 c competition but experimental work does not support this possibility 7 If two species coexist indefinitely in nature then the two species may now be said by definition of coexistence to be in different ecological niches C This would appea to be a circular definition and seems not to be amenable to experimental disproof It has therefore bothered a number of biologists as an example of dogma and needed experimental proof 1 Garrett Hardin 1960 The Competitive Exclusion Principle Science 131 1292 1297 states that Gause s Law the Competitive Exclusion Principle is a mathematical Null Hypothesis in which like the HardyWeinberg Law the violations are biologically significant 2 This question has led to many studies of species that coexist Charles Darwin appreciated this relationship when he saw that closely related species rarely coexisted 3 Next it should be emphasized that botanists have long observed 7 as did Darwin 7 that seedlings competed some lived some died through competition 4 Early authors discussed competition as it occurred in an ecological succession and in the shading out of plants in a forest Tansley 1914 5 Tansley 1917 himself did experimental work with Galium sylvestre and Galium saxatz39le in England and showed that G sylvestre seeds germinate and grow more vigorously on limestone soil and G saxatz39le seeds do better on sandy soils each species ousting the other species 6 However simply to nd differences between species is not enough 7 One must prove that the differences found are the differences that allow coexistence III Laboratory experimentation on competitive exclusion A Gause G F 1934 Univ Moscow did critical experiments that confirmed the principle of competitive exclusion l Paramecium caudatum vs P aurelia figl44 in Smiths a The Paramecium species were cultured in centrifuge tubes Both species are bacteria feeders and the bacteria fed on an oatmeal medium that was added with water after centrifuging and decanting the tubes Fquot Each population would increase in numbers and level off at a population representing K for the conditions that is the food and space available When Gause put the two species together in the centrifuge tube and allowed the populations to grow together P aurelia grew more rapidly and always won under the laboratory conditions 0 2 So how do the two species survive in nature when in the laboratory situation one species eliminated the other a Gause reasoned that somewhere P caudatum must be the better competitor b Gause left in old water by decanting a little water food concentrate was added directly so waste products now can accumulate in the tube c Now P caudatum won under conditions of water being full of metabolites This was also true in nature 3 In another experiment Gause found that P aurelia and P bursaria coexisted in the same culture a Further observation showed that P aurelia occupied the top of the culture tube and P bursaria the bottom where the oxygen was lower partitioning space in the tube by oxygen concentration Fquot Bubbling oxygenrich air or carbon dioxide richair eliminate the partition and one species survived 4 Gause thus showed in his work that stable populations of 2 or more species cannot continuously occupy the same ecological niche in the same place that there is for each species one niche in each ecosystem B Work on our beetles by Park at the University of Chicago 1 Tribolz39um confusum vs T castaneum Flour beetles are easy to maintain in laboratory in jars of our The our is both food and habitat for the adults and larvae Temperature and humidity is very important with respect to r The species with the highest rate of increase under a particular set of conditions wins a Under hotmoist conditions T castaneum wins Under colddry conditions T confusum wins 6 When r1 is near r2 conditions in between hotcold moistdry then stochastic processes or chance determines the outcome Coexistence did not occur One species eliminated the other 0 If Adelina a sporozoan that infects both species is added to the culture then T castaneum always wins 3 1 Genetic strains within a population differ greatly in competitive ability Inbred populations produced strains with reduced variability these lost the competition normally won by the species D Part of the interference of one species over the other other was the eating of the eggs of the other species which can be called intraguild predation See Smiths pg 300 2 Rhizoperta Lesser Grain Borer vs Oryzaephz39lus Rice Weevil cultured in rice in jars a In mixed cultures Rhizopertaalways wins b If glass tubing is added which the rice weevil and rice can get inside of and Rhizoperta cannot c Then the tubing acts to partition the habitat spatially and both species coexisted 2 C hlorohydra viridissima vs Hydra littoralz39s one with a green symbiont the other without Both catch small planktonic animals for food a In mixed cultures H littoralis wins in the dark b C viridissima wins in the light showing the advantage of having an algal symbiont for additional energy VII Field Examples of Competitive Exclusion A Cormorants D Lack 1 In 1945 Lack obtained support from the British government to study effect of cormorants on the shing industry that had complained that the cormorants were pests 2 This allowed Lack to study the two Cormorants the Great Cormorant Phalacrocorax Garbo and the Shag P aristotelis that seemed to be occupying the same niche 3 Lack however showed that the species had the following overlapping differences Great Cormorant Shag fishes mostly out at sea fishes mostly in estuaries fishes at intermediate depths fishes close to bottom ate sand eels and herringlike fish ate atfish and shrimp nests high on at broad cliffs nests on low narrow ledges 4 Lack concluded that these two species were in different niches and were not competing directly with each other although there were overlaps in resource use Incidentally he showed that the birds were essentially harmless and that the fishermen were to blame for the poor fish catch through their own over harvesting B Connell 1961 Barnacles in Scotland N 4 5 C hthamalus stellatus the brown bamacle was found throughout tidal zone on the Isle of Cumbrae Scotland except where Balanus balanoides the acorn barnacle was present C hthamalus was restricted to the upper tidal zone where it competes better because it can take drying out better than Balanus Lower tidal levels were dominated by Balanus even though Chthamalus also settled there and could grow faster than in the upper tidal zone The greatest mortality in Chthamalus was due to the ability of Balanus to smother undercut or crush the more fragile Chthamalus which occurred seasonally during the time of the most rapid growth of Balanus This allowed Balanus to dominate the low tide zone C MacArthur 1958 one of Hutchinson s students studied Wood Warbler competition 1 Dendroica the Wood Warblers formed a guild and a taxocene of five species that were feeding on the same species spruce budworms on spruce and balsam fir of the Canadian Taiga every summer after migrating from the Neotropical region their over wintering area MacArthur made careful observations over several years and recorded the time and location in the trees of feeding by the Bay breasted Blackbumian Blackthroated Green Cape May and the Myrtle Yellow rumped Warblers He showed diagrammed in class that each species exploits a different part of the tree for food that there were statistically significant differences in the feeding behavior of the species which indicated that the five species were partitioning the available resources D In Africa many big herbivorous mammals feed on redtop grass 1 the question was were they all in the same niche 2 Careful study of their feeding showed that in this guild the species were distinctly different in their ecological niches Zebra 7 feeds on long dry stems finds water the best of the group Wildebeest 7 feeds on green side shoots has the best sense of smell Topi 7 feeds on the dry short grass Thompson s Gazelle 7 eats lower leaves and seeds has the best vision 3 Moreover each species differs in size and has different strategies for defense and survival so each one overall occupies a different ecological niche E Competition can therefore result in niche divergence with respect to food space use time of feeding activity or habitat and life cycle environmental adaptations VIII Competition and Niche Theory A History 1 Grinnell 1904 1917 who studied birds in California conceptualized the division of resources and space as an ecological niche Grinnell 1911 defined ecological niche as space function 2 Charles Elton 1927 in his textbook on animal ecology because there already was the word habitat restricted the concept of the niche to role of a species a Habitat 7 space or where the species is found including ecophysiological adaptations to the physical conditions b Ecological niche 7 function or role of a species including not only what it eats but how it relates to the other species in terms of predation life cycles periodicity etc 0 This was accepted by Odum in his important genral textbook in which he drew a parallel between an office where a person worked and what his profession was 3 Hutchinson 1957 Hypervolume concept a He observed that many factors together define an ecological niche b He proposed that species adaptations of both space and role together were dimensions and that species could be thus be compared with another species geometrically Fig 145 Smiths The geometric equations for dimensions going from ordinary three dimensional space into a multidimensional niche hypervolume d He also returned the concept of the niche to the concept of Grinnell as a unit that includes both space and function as these were all dimensions treated equally mathematically 4 Hutchinson further proposed that each species has a fundamental niche based on the potential ofthe species to use resources a concept close to the idea of an economic carrying capacity 5 Next he observed that every species lives in the context of other species some predators some competitors some mutualistic and therefore in nature in the ecosystem each species has a realized niche based on interactions with other species and normally the realized niche is smaller than the fundamental niche Recognize that this concept is close to that of the ecological carrying capacity See 6 Whittaker Levin and Root 1973 proposed the word Ecotope They argued that Elton had correctly observed that space and function were different concepts and that Hutchinson was essentially throwing the baby out with the bath water by returning niche to Grinnell s original concept They proposed to return to Elton s concept a Habitat space and environmental adaptations b Ecological niche role or function of a species c What was needed was new term ecotope to encapsulate the idea of Grinnell and Hutchinson So similarly there is a fundamental and a realized Ecotope Your text books has ignored Whittaker Levin and Root s excellent word Ecotopeil accept it as an intellectually excellent concept B Niche or ecotope dynamics of resource use 1 When a resource has been divided among a set of species this is termed niche partitioning 2 When a set of species evolves to partition a resource this is called species packing 3 The set of species dividing a resource is called a guild by Root If related taxonomically like the warblers of McArthur s work it is called a taxocene by Hutchinson Often ecologists display their taxonomic biases by ignoring other organisms that are exploiting a resource focusing on the organisms they happen to know 4 When other species come into the resource use the niches of the species may UI 9 evolve to shift becoming more specialized in its use of a the resource This is called niche shift and it commonly occurs when related species become sympam39c in their evolution and affect the classical ecological niche based on function When in parapatry the niche shift would instead involve the habitat adaptations of the species Niche contraction occurs when more species are packed into the resource use Niche expansion occurs when species become extinct or a species invades an area where its competitors are absent so that the niche expands to use the resources available Niche overlap is a normal situation it is rarely either or but the overlap leaves sufficient resources to each species to maintain itself in its niche Character displacement occurs when the species become taxonomically more different in the zone of geographical interaction either in sympatry or in parapatry C Ecological Equivalents was proposed by Grinnell 1924 N E 4 Species in different areas that occupy similar ecotopes may be competitively in con ict if brought together so that one species will eliminate the other following Gause s Law Thanks to human intervention this is happening frequently with the expected results of one species being eliminated When the American Gray Squirrel S carolinensz39s was introduced into England the native Red Squirrel has been eliminated from a large area in 30 years It is very difficult to actually prove that one species has eliminated another In paleontology it is frequently seen that when a taxon becomes extinct it is simultaneously replaced by a different taxon suggesting competitive replacement Even more persuasive is when a taxon invades a new area as when North American placental predators invaded South America and eliminated most marsupial predators and North American vertebrate herbivores similarly eliminated many unusual South American herbivores The same is now occurring right now in Australia and on most islands 9 All over the world species are undergoing extinction In general species from larger areas or from centers of evolutionary diversity eliminate those of smaller areas or areas of lesser diversity This is probably because larger areas have greater diversities meaning more competition during evolution hence species from such areas are better competitors Elton in his book on the ecology of invasions made the gloomy prediction that due to effect of man in facilitating invasions of animals and plants that ultimately the world is going to become ecologically the same everywhere due to the interactions of ecological equivalents in which one of the competing species becomes extinct Community Ecology III Biodiversity and Mankind I Introduction A In this last lecture I want to ask you to rst look at our biosphere and think about the amazing diversity of life B Then second let us look at the effect our species has on biodiversity and indeed on the fate of our planet our world ecosystem and our own survival II Biodiversity A Measurements of biodiversity 1 Crude Species Richness a Number of species per area acre hectare square mile etc b Unde ned 7 such as a political region Texas Mexico etc 2 g Species Richness a Number of species per biotope b De ned by community biocoenosis 3 Species Richness a Between community numbers of species b This is the species richness ofa de ned set of communities often adjacent to each other as of a barrier island or a river valley 4 Species Diversity a Combines number of species richness with number of individuals per species b Crude 0c amp 5 Diversity as for species richness above c Shannon Weiner Index of Diversity 8 H ZPilogPi Pi Ni N total il i ranking of species Ni numbered of individuals of a species d More even the number of individuals per species the more diverse is the community e ShannonWeiner Index measures Information Content combines Species Richness with Species Evenness 5 Compare communities A with B a Each with 1000 individuals each with 10 species but community A with much more of one species See graphs AampB in class 6 Community A The most common species is very abundant 7 less even iless diverse iless healthy imore stressed 7 Community B No one species is extremely abundant iMore even iMore diverse iLess healthy iLess stressed B Communities and biodiversity 1 Under stress communities have a Fewer species b Lower species diversity 2 Unstressed communities have 3 a More species b Higher species diversity Effect of Physical Stress a Natural effectsispace salinity coldness drought etc b Effects of humancaused stress pollution perturbations etc have a similar negative effect on diversity C Patterns of Diversity in the World Worldwide patterns of diversity Many taxa show a remarkable increase from the poles to the equator See P 24 P24a 24b in class notes Next some taxa as the insects and the owering plants show an amazing diversity that puts us mammals to shame see P25b in class notes E Especially for insects we are far from knowing the living fauna In Erwin s little paper see P 25 are some calculations based on the fauna of beetles on one representative small tree in the dry tropical forest If Erwin is right there are 30 million not 15 million species of insects usually cited D Why so many species E Fquot 0 3 1 D quot1 Moquot A rthur Stabilitv HVpothesis SpeciesRich communities are more stable because what happens to one species of many will probably have little effect on the community while in speciespoor community what happens to one could have a great effect on the community Evolution packs more species into Guilds This is a widespread phenomenon in natural communities showing that this must be an important force in community ecology Consider in Predator Prey Cycles that when there are few species there are unstable cycles w recall Gause s work On the other hand when there are many species there are much more stable cycles Similarly plant herbivore carnivore interactions generate more species through interactions of the ecological niches Through speciation more specialization is possible with the formation of more ecological niches This requires time and space in the sense of geographical isolation May believes stable environments leads to species richness Actually both species stability and biotope stability are important and relates to the next factor physical stability of equable conditions 2 Most important factor is stable equable environments that have geologically existed for a long time a Fquot O In such environments evolution w natural selection operates mostly on interspecific relationships as above not physical adaptations The great importance of stability is shown by benthic communities of the Archibenthic zone 2000 M down cold low food but very stable physically resulting in high species diversity Under physically stressful conditions too salty too cold too acid too dry too hot too polluted species diversity drops d Under nonstressful conditions warm enough not too cold not too hot not too salty not too dry high species diversity readily evolves 3 Area w island biogeography studies show that the larger the island is the more species it has everything else being the same a Fquot 0 3 1 D Darlington compared faunas of amphibians and reptiles herps on islands of West Indies see P43 in class notes He estimated that a tenfold increase in area resulted in a doubling of species Smiths Fig 238 show the same calculations by Preston for birds of islands in the East Indies Preston developed methods of measuring the slope z for increase in number of species as related to area McArthur amp Wilson in their Theory of Island Biogeography stated everything else being the same that an equilibrium fauna is a balance between immigration and extinction and the size of the island See Smiths Figs 239 and 2310 The equilibrium island population varies with the conditions on the island and with the kinds of organisms being considered Islands come in all types Mountain tops host plants ecological successions a fragmented range can all be seen as islands isolated from other islands It is critical to realize that area is essential for the survival of natural communities The larger the number of species in the community the larger the area that should be set aside for a nature reserve Recall also that populations should be sufficient to maintain genetic health and avoid inbreeding The more species present the fewer individuals per species thus the greater need for sufficient space for a species population to survive in good genetic health 4 Heterogeneity of the biotopes of the ecosystems present a Fquot O Disturbances promote diversity if moderate Some species are only found in disturbed habitats as in an ecological succession The successional species provide a suite of species particular to the sere Mountains seashores like the barrier islands rivers and deltas provide a variety of different ecosystems for species to live A tropical high island for example is very different from a low island in terms of an equilibrium community A temperate or arctic island similarly will be very different 5 6 High Biomass 7 forests and coral reefs have more places for organisms to live in and are accordingly very species rich a In forests and coral reefs there is not only a place to live but also a source of food to which to adapt b Think of all possibilities of symbioses there are a staggering number of opportunities for interspecifrc relationships which produces a magnifier effect Interestingly enough aside from the high biomass factor productivity seems to be a minor factor in biological diversity a The cold Northern oceans are very productive but species poor in plankton as compared to the tropical seas that are like biological deserts but are speciesrich Copepod diversities show this very well b The chaparral shrub vegetation of the Mediterranean climate areas is another instructive example High species diversity of the plant communities contrasts with the relatively low net primary productivity of these areas with cold rainy winters and dry hot summers E Areas with the Highest Species Diversity are under severe attack 1 2 E UI These are especially the tropical forests and the coral reefs These are species rich but fragile communities Tropical conditions are not conducive to the evolution of strategies resistant to stress because the very unstressful equable conditions that promote the evolution of high species diversity render the community unable to handle the stress of Mankind In contrast in temperate areas the communities are species poor but resilient communities because these communities have evolved in adaptation to a lot of natural stress and thus have much better ability to handle the stresses imposed by man Unfortunately such rich communities especially those of the tropical forests are under incredible attack right now Do read the interesting paper by Hugh Iltis F 2629 written back in 1983 It is far far worse now We are having a hard enough time just in the USA right now fighting for the survival of the Old Growth Ancient Ecosystems of the Paci c Northwest Read the little editorial on P 49 in your class notes on how the spotted owl is actually a symbol for the Ancient Forest ecosystem under attack We have already cut about 95 of the Old Growth Forest Why not leave some to awe future generations III How does Homo sapiens endanger other species A Direct Effects 1 Overexploitation reduce populations so low that they cannot recover Whales 7 the Japanese will hunt whales until it is no longer economically useful Many of our commercial sh stocks are in a bad way and are seriously endangered The cod may not come back as other species are replacing it Fur business predator control uncontrolled hunting can do in species which is why we have hunting and shing laws These are largely lacking or not enforced in the tropical parts of the world In Africa the hunting of bush meat is seriously endangering many species including our kin the monkeys and Great Apes Fun is the worst reason to render a species extinct a Passenger Pigeons the most abundant bird ever to exist Audubon estimated one ock to consist of 2 billion birds b Used as food for a short while c But the biggest market was supplying targets for shooting galleries in New York In 1878 one hunter shipped three million birds from Michigan to New York for this sport d Consequently the last wild pigeon was seen in Michigan in 1889 The LE ofthe species died in the Cincinnati zoo in 1914 Her name was Martha e This species was vulnerable because it behavior required large ocks for reproduction and survival E Indirect Effects 1 Erosion of hillsides through urbanization in Hawaii destroys coral reefs around islands of Hawaii Pollution of the sea from Miami is seriously impacting the coral reefs of Key West Florida Coral reefs grow only in sunlight shallow waters and are very sensitive to pollution of all kinds Destruction of natural habitats a Of sixtyeight species of endemic birds in Hawaii when the Europeans first arrived fortyone are now extinct including most of the honeycreepers It was also discovered that a great many other bird species had become extinct with the coming of the Polynesians O Deforestation of the tropics will eliminate the habitats of millions of species This includes farming in Africa for examples cheetahs and elephants are not wanted Big animals are not compatible with human agriculture in most places India an exception as large animals are accepted as natural and normal inhabitants for religious intellectual and social reasons FL Coral reefs in the rich IndoPacific areas are taking a beating because of the marine aquarium sh trade promotes unscrupulous collectors to use dynamite or cyanide or to get the sh out destroying the reef in the process 3 Man has been rendering species extinct for a long time a Big mammal extinctions in North American occurred simultaneously with the invasion of big game hunting Man at end of the Pleistocene about 12000 years ago Similar Megafauna extinctions occurred in Eurasia and in Australia with the advent of man Fquot Invasion of islands by Man in Hawaii New Zealand Madagascar has continued the pattern of mass extinctions especially of mammals and birds 0 Australia is suffering new waves of extinctions now in the small marsupial mammals through niche exclusion by the invasion of placental mammals such as deer dogs cats rabbits mice and rats 3 1 Actually right now the great extinctions are occurring in the main tropical areas now with deforestation for agriculture and fuel Read the article P 49a and 49b predicting the greatest Mass Extinction coming that will rival that at the end of the Cretaceous 65 million years ago or perhaps the worst on land since the end of the Paleozoic 230 million years ago Why save natural areas Why prevent extinctions Why care 1 First species are irreplaceable Extinction is forever You can t bring then back 2 Ethics who gives us the right to drive other species into extinction 3 Esthetics organisms are beautiful flowers trees butter ies birds and many others We enjoy zoos botanical gardens etc many enjoy birding fishing and hunting So why destroy them 4 Education life is an everamazing phenomenon worthy of learning about appreciating for our knowledge about the world of living things 5 Scienti c value there are about 200000 species of owering plants Only about 5000 have been examined for potential medical drugs Recall that plants produce a remarkable array of chemicals in defense against insects and plant pathogenic fungi 6 There are other things of potential practical economic values such as woods fruits nuts and who knows what Often forests are destroyed simply for f1rewood or to raise nonin ationary beef to pay international loans 7 Stability Gaia our life support system We are but one of many species and as animals we are utterly dependent on the world ecosystem for our support the very air we breathe 8 Stewardshipithis is our spaceship We can hardly go elsewhere Should we not take care of it Should not our religions take awe of our Earth a jewel of creation Aldo Leopold s book Sand Count Almanac proposes the idea of the land ethic he has a good discussion of this quite practical ideal V Loss of biodiversity A It now seems inevitable that we will be witnessing a wave of extinction that will rival the end of the Paleozoic when 90 of the animals went extinct This one is being brought about by one species us Homo sapiens surely and logically our populations have become an ecological cancer of Gaia Can she survive us B Human Population Growth 1 Show overheads of patterns of population growth 2 Somehow our populations must be brought under control or it will be done for us by nature Africa is showing this horrible pattern now 3 Some even think there isn t room for other species and they should be eliminated This is dangerous thinking for the world ecosystem with all its plants animals and microbes is the life support system of our planet and for us C Human overexploitation of the world 1 On the other hand the very countries that have populations most under control are most likely to be the worst eXploiters of the world s resources Show overheads 4 Countries with the most rapid population growth have the least resources V39 0 gt1 Some how we must bring into balance not only population growth but also our exploitation of the world s resources especially fossil energy and we must take care of our human and industrial wastes including nuclear wastes Waste disposal is an incredibly expensive program yet most industries do not calculate into their balance sheets the costs of cleaning up the wastes that they produce and make it a political problem of the govemmentuspaying for the cleanup If we do not repair this we will drown in our own wastes But worse our species seems bent on suicidal wars of aggression based on ideologies and on false economic imperatives that operate against solving the problem of living with our beautiful planet But remember these are choices and we are an intelligent species indeed a species aware of itself and aware of the importance of saving our world ecosystem for future generations So can we make the right choices given the courage and will I hope I can send you out as missionaries to educate others Thank you I enjoyed you in my class in Ecology ENERGY IN ECOSYSTEMS I Introduction 2 All organisms process energy 3 Use energy to build and maintain complexity at all levels from the molecular to the ecosystem 4 Obey laws of thermodynamics and entropy 5 Biomass itself is stored energy 6 From view ofthe species each species s share of ecosystem resources can be summarized by the energy processed by the species 7 Important to remember that entire earth has a physical energy budget E in E out that is the sun s radiation in infrared out 9 This processing of energy leads to climateWe ll talk about that later II In ux of Energy 1 Solar ux 194 Langleys gmcalcmzmin 13 x 1023gm calyear 700 gram calories per cmz day 2 About 57 reaches earth as incident light rest is re ected or absorbed approximately About 134 Langleys at sea level on clear day with dry air 3 Heats the earth moves air amp water and drives photosynthesis 4 Energy from 0lu 100 nm to 10u UV 100 nm to 380 nm 4 Visible 380 to 770 nm 44 Infrared 770 to 10000nm 52 7 Energy amount differs inversely proportional to wave length 1 mole 6x1023 photons l einstein for example Red light 067u 42000 cal E Blue light 47u 60000 calE 6 Note that 03 in the stratosphere absorbs most UV which process protects life 7 Plants absorb in blue and red infrared for photosynthesis III Primary Productivity A Photosynthesis lReaction Formula Text pg 86 oversimplifies in number of H20 molecules 12 H20 6 co2 E 709 Kcal chlorophyll gtC6H1206 60211 6H20U 2 Light Reaction absorption of energy Splits H20 a Chlorophyll a universal in all photosynthesis first it absorbs 2 e39 from splitting H20 reduces Chlorophyll a and second it captures more energy b Chlorophyta green land plants also have chlorophyll b both a and b absorb in blue amp red infrared c Algae diverse some with chlorophyll c d e different colors all have a Many have accessory pigments to absorb light carotenoids avoids and phycobilins especially in deeper water because H20 absorbs red light first thus red amp brown algae don t re ect green but use green Something to think about if yellow and green are higher in energy why aren t they used directly by chlorophyll DJ 3 Light reaction splits H20 releases 02 8 N E 4 V39 d Photosystem II P580 absorbs 2e39from H20 reduces Chlorophyll a e Photosystem I P700 absorbs more energy and captures the hydrogens NADP3NADPH See diagram in class notes Dark reaction captures C02 CalvinBenson Cycle a Ribulose biphosphate carboxylaseoxygenase Rubisco b combines with C0232PGA 3 phosphoglycolate c produces sugar glucose Ef ciency in dim red light 320 Kca13120 Kcal 38 2133 in Lab 12 19 at best in the eld In real life conditions it s very much lower HatchSlack or C4 cycle PEP P39 r39 ruvatc Hot a PEP gathers C02 dark reaction in mesophyll and transports organic acids to bundle reducing C02 in mesophyll thus promoting the dark reaction in bundle cells b Hot conditions with much light amp avoids Photooxidation by Rubisco Crassulacean Acid Metabolism CAM Desert adaptation of reversal in stomata behavior a Plants close stomata during day to conserve moisture and light reaction is carried out capturing energy b At night stomata open to allow atmosphere to enter and C02 is stored as crassulacean aspartic and malic acids in vacuoles for the dark reaction of photosynthesis This allows CQ to be concentrated c When photosynthesis is completed the C02 is released to replace consumed C02 in quantities also large enough to prevent photoxidation Both of these processes have evolved in unrelated plants and often in related J39 SpeCieS are bOth C3 and C4 species thus these processes are polyphyletic Productivity Terminology 1 Gross Primary Productivity GPP a Total xed energy by Photosynthesis b This is related to total C02 uptake using labeled C14 or 0 generated Net Primary Productivity NPP a Gross Primary Productivity less plant respiration plant growth NPP b Also NPP Plant Growth measured hetertroph consumption of plants Secondary Productivity a Heterotroph productivity Animals also Fungi and Bacteria b Similarly Gross Secondary Production amp Net Secondary Production In ecosystems GPP NPP P resp Gross SP or GPP NPP P resp NSP animal resp disregarding inputs amp outputs from other ecosystems Net Ecosystem Productivity total Productivityitotal Respiration of entire ecosystem also called Net Community Productivity note the delayed consumption a In natural steady state climax communities this is essentially zero on the average Whole biosphere zero 0 9 b Now probably negative in the world due to deforestation In the distant past productivity exceeded respiration which became oil and coal Standing Crop Instantaneous measure of Biomass a clearly changes over time and with changes in Ecosystem Productivity b Seasonal amp long term changes in ecosystem affect standing crop Turnover rate Standing Crop divided by the Net Primary Productivity Allochthonous Productivity is input from other ecosystems autochthonous is productivity within a ecosystem C Measures of Productivity N E E 4 IvI 9 D Total N L Usually use harvest method using dry NPP expressed as gmmz day month year NPP since this quantity is the production for consumers including us Also it is difficult to measure losses to heterotrophs and GPP is often difficult to measure and this requires knowledge of plant respiration GPP dark and light bottles put bags over plants in air In this method one measures 02 and C02 concentrations a C02 Production C02 consumption Productivity on carbon b 0 consumption 02 Production Productivity on oxygen Uptake of C14 either by measurement or use C02 infrared analyzer of a stream of air Aquatic systems Na amp H14CO339 incubate 6 hr measure uptake of radiocarbon Chlorophyll a concentration in H20 do a regression with GPP Evaporation of plant photosynthesis regression GPP 7001000 gmHZO gm NPP Caloric measures in a bomb calorimeter of the standing crop a 4 Kcal per gram of carbohydrate plant material often 425 Kcal used as land plants include some protein amp fat b 45 aquatic vascular plants less cellulose c 49 for phytoplankton less carbohydrates d 5 for animals Protein Normal e 7 for fat storage 4 for glycogen stores f Harvest works best for annual plants Roots a problem to measure g Perennials more difficult because it s added on each year to wood and biomass falls to the ground as leaves and wood h 1200 1500 gmmzyr typical of temperate forests 3000 in tropics World Primary Productivity Gross Total fixed Carbonorganics matterEnergy affected by Photosynthesis total energy captured a Measure by 0 generated C02 released by plant respiration b by uptake of 14 C 14C released C02 or HCO339 c Difficult to be accurate Net Gross Plant respiratory use Heterotroph consumption Net Ecosystem Production Measurements of NPP Productivity 90quot d 4 Max Gmmzday or year or month or growing season energy assumed 4 x Gm Qalories Kilocalories must take care for comparable results watch wet weight versus dry weight Russians used wet weight imum Productivity a Nowhere at maximum possible 77gmm2 100 days 7700year at 12 b efficiency of visible light 3 8 in monochromatic red always much less for the whole world 015 to 018 5 Most of the world is too cold too dry too mountainous too low in nutrients a b c d e 6 Prod 80 low productivity 01 x 103gmm2year un t for agriculture 10 of total agricultural land from fair to excellent Highest productivity in forests both in temperate and tropical Total productivity and in productivity per area See Odum s summary on P 7 also table of Whittaker and Likens P 6 uctivities of major ecosystems Note the following generalizations a Despite the area ofthe oceans 361x106 Km being more than twice area of the land 149x106 sz b Net Productivity Oceans 55 x 109 metric tons Land 109 x 109 metric 172 5x109 tons iTherefore 23 land 1 3 marine 7 you can see that the sea cannot be the cornucopia of the future land must be source of food c Moreover consider the harvest available for we eat standing crop Standing Crop Biomass Oceans 33 x 109 metric tons Land 1855 x 109 metric tons d Sea very limited areas of high productivity in upwelling The open seas are deserts E Elk59 Seasonality in Productivity JenHu a Hawaiian agronomist Gates 1971 observed Tropical rain forest only 25 gmmzday for a whole year but crops that we can eat need a growing season of longer days 4 month growing season 50 N cold limits above 60 N 38gm2m2 day 8 month growing season 30gmm2day to support food to eat 275 gmmz day required for food to support a high civilization five nations export Iowa would be the second highest exporter of food after the rest of the USA Ecological Genetics A Background Recall the functions of ecosystems Energy flow and Nutrient cycling we have already covered 1 Recall that the third function is the 39 39 of the L39 the 39 39 39 39 39 community of an ecosystemall the animals plants and microbes What maintains the number of species which species how many how large are the individuals in the species populations and where they exist in space and time in the ecosystem 2 Fundamental concept therefore is that of the species which is a population concept not an individual organism concept Realize that the biological world is divisible into species which are basic to all biology from the molecular to the ecosystem 3 Recall that each species has a distinct habitat where it lives and ecological niche what it does which together comprise the Ecotope the entire ecology of a species 4 Each species each individual is programmed by its DNA its genes that code RNA and proteins some for enzymes others for structures which together determine the structural and functional uniqueness of each individual organism of each species 5 Each population then represents a gene pool the sum of all the genes in the population Therefore the species the sum of all the shared gene pools of all the populations The genes are shared through descent and through sex 6 The Genotype DNA is expressed through development into the phenotype from egg to adult Species differ in phenotypic plasticity This plasticity conferred by the genes too although plasticity can be called non genetic variation based on environmental in uences such population differences are called ecophenotypes a Motile highly organized organisms like higher animals show little plasticity so the phenotype closely corresponds to the genotype despite considerable environmental differences b Sessile moreloosely organized organisms such as plants and colonial animals can have great variations in phenotype even while having the same genes even on the same organism as pond weeds with narrow leaves under water broad leaves on the surface of the water B Idea of Evolution and Natural selection 1 A clear understanding of ecological genetics must begin with natural selection a phenomenon that is happening all the time in all species 2 To best understand natural selection conceptually it s good to look at it as Darwin and Wallace did in the last century before genetics and inheritance were understood Neither Darwin nor Wallace ever understood what Gregor Mendel was raving about with his peas nor did anybody else until 1900 when four scientists simultaneously rediscovered Mendel s Laws of Genetics 3 The idea of natural selection was first presented July 1 1858 in joint paper by Charles Darwin and Alfred Wallace 4 Darwin then a mature wellrespected scientist had conceived of this idea twenty years earlier during his trip around the world on H M S Beagle especially in visiting the Galapagos Islands Wallace a young man while doing fieldwork in the East Indies came upon the same idea and they agreed to publish together What they did is to present a mechanism for evolution that is natural selection 5 Let s first examine the thinking of Darwin and Wallace It was based on 3 observations and 2 conclusions that anyone can make Observation One All species have the capacity for geometric or better logarithmic increase in numbers Observation Two In nature species populations usually remain roughly the same varying from year to year but showing homeostatic variation This leads to Conclusion One Clearly not all zygotes survive to reproduce This incidentally was Malthus s conclusion Both Darwin and Wallace had read Malthus s 1798 dreary prediction of punishment by war pestilence and death for sinning and making babies so populations increase geometrically beyond the means to support them which means can only increase arithmetically Observation III Individuals in a population vary in inheritable characteristics Remember that while biology then had no genetics the idea of inheritance was a general observation by biologists indeed nearly everyone understood it This leads to Conclusion 11 Given that most zygotes die before reproducing and zygotes vary in inheritance it follows that whatever allowed certain individuals to survive and reproduce would be inherited Thus their inheritance would be selected by nature Natural Selection Please note this is M the survival of the ttest the largest the strongest etc but the ability to reproduce the next generation Fitness is reproductive success of generation to generation Survival is important only if reproduction is enhanced 5 Darwin had spent over 20 years gathering data and also making a reputation for himself because knew that his ideas would be controversial He later published in 1865 Origin of Species a long book that Darwin considered to be a just short version of his original manuscript His contributions among others are as follows a He gave evidence for the mechanism of natural selection although he never understood genetics b He gave evidence for the occurrence of biological evolution that we are all related by descent c Realized that taxonomy is a description of this descent so taxonomists should endeavor to make classifications that re ected evolution not creation by divine beings d Evolution then makes understandable the fossil record of change over geological time No need for new creations as Cuvier had suggested to explain fossils e Evolution makes understandable the geographical distributions of animals and plants and endemicity on islands that have always stimulated biological thought f Evolution makes understandable the similarities and dissimilarities of living organismsicomparative morphology comparative embryology comparative physiology comparative cytology and now comparative genetics in which similarities in DNA and proteins are being used to show relationships among organisms As G G Simpson a famous paleontologist said Nothing in biology makes sense without evolution 6 Evolution happens all the time look at breeds of animals and plants produced by arti cial selection Darwin studied these carefully He raised pigeons and studied their inheritance but never discovered the why of inheritance nor did he ever understand Mendel s work Pigeon genetics incidentally is very complex peas very simple 7 Accidental real life experiments a Pepper moths evolving Industrial melanism b Insects evolving resistance to pesticides and c Microbes evolving resistance to antibiotics All show natural selection at work 8 Evolution is an on going process in all species adapting them to their habitat and ecological niche Evolutionary Ecology Ecological genetics or as Hutchinson phrased it The evolutionary play in the ecological theater C Genetics Mendelian Populations and Gene Frequencies 1 Let us now relate the thinking of Darwin and Wallace to modern genetics a wedding that led to the Synthetic Theory of Evolution a At first a stormy courtship as early geneticists from 1900 to 1920 sought to explain evolution through macromutations not natural selection b In 1930 s science ofpopulation genetics was founded by R A Fisher J B S Haldane S Wright amp S Chetverikov who brought genetics and Darwinian Natural Selection together c Let us brie y consider some basic genetics which show be review 2 Mendelian populations are interbreeding organisms of a species occupying the same area or neighborhood Such populations are often called demes especially in botanical studies 3 Chromosomes are characteristic of eukaryotes DNA is dispersed in nucleus but condenses to form tightly coiled structures called chromosomes Number varies with species Prokaryotes as do mitochondria have one circular strand of DNA that never condenses to form chromosomes This is evidence for bacterial origin of mitochondria 4 Alleles are different forms of the same physiological gene or cistrons that occur at the same location on the chromosome 5 Diploid means 2N two sets of chromosomes two sets of genes haploid means one set of chromosomes and genes 6 Homozygotes both chromosomes have same allele in heterozygotes different alleles Use capital letters for dominant genes little letters for recessive genes sometimes a blending of alleles occur in phenotype 7 Genotypes are the actual genes phenotype the expression of genes genotype directs development into the phenotype 8 Mitosis replicates the genotype that is the genome all the DNA is duplicated with the exception of the mitochondria which divide by fission as do bacteria 9 Meiosis reduces the diploid number to haploid number which in animals are the IN gametes that fuse together syngamy to form the 2N organisms In higher plants the embryophytes the haploid cell divides to form the gametophyte that make the eggs and sperms that fuse to form the diploid sporophyte in which meiosis occurs 10 Sex in eukaryotes accelerates genetic recombinationas compared to procaryotes Results in great variation in genotypes as follows 11 First chromosome recombination through the shuf ing of the chromosomes in meiosis Let n number of pairs of homologous chromosomes 2 number of different combinations of chromosomes so in man with 23 pairs recombinant gametes would 223 Next consider the number of recombinants that occurs in the formation of the diploid organism Enormous variety results 12 Second during meiosis crossing over occurs between homologous chromosomes during synapsis of the homologous chromosomes which causes reshuf ing of the genes between the homologous chromosomes this creates still more variety 13 Contrast this with asexual reproduction in which the same genotype by mitosis is reproduced to form clones Such clones can vary only by gene mutations and some chromosome mutations 14 Often in higher plants there is often mixed asexual and sexual reproduction 15 Prokaryote have ssion No meiosis no syngamy In such primitive seX genes may be moved by viruses or by loops of DNA Prokaryotes depend on rapid reproduction and mutations in their evolution Loops or plasmids can transfer genes widely 16 Gene 11 I 39 A J quot r r 39 quot can be considered a gene pool The sum ofthe alleles at a location is 100 or 10 Let frequency ofA a10 Let p frequency of A dominant gene q frequency of a It helps here to make a Punnett square to see the combinations of alleles A and a Mendel s first Law You can do this using the simple binomial equation pql Aalthen p 12 p22 pq q2 Thus 1 AAp2 2 Aa2 pq laaq2 Let gene frequencies p A 06 and q a 04 Multiple these in Punnett square for genotype ratios If you know the recessive q2 then you can solve for the gene frequency of the recessive gene by nding the square root If a dangerous gene has the phenotype frequency of 01 then the gene has a frequency of 01 D HARDY WEINBERG Chetverikov LAW 1 Defines evolution as changes in gene frequencies This is a genetic measure of evolutionary change 2 It predicts that in J quot r r 39 quot the gene f 1 should remain about the same from generation to generation if 4 conditions are met That is genetically speaking n0 evolution has occurred as there has been no changes in gene frequencies If any of these four conditions are violated then gene frequencies can change and evolution occur Condition 1 Population must be large a If a population is small generally lt100 individuals then frequencies may change by chance by genetic drift as it was termed by Sewell Wright This is usually nonadaptive evolution by chance b The Founder Principle is an extreme example Consider that if single fertilized female bug colonizes an island ithen her eggs will give only small sample of genes of the original source population c Small populations run the danger of becoming inbred homozygous and expressing deleterious recessive genes as well Small populations are genetically dangerous Condition 11 Must be no immigration 0r emigration a Because individuals leaving from or arriving into the population carry genes this violation leads to changes in gene frequencies by Gene ow that is genes may enter or leave the population b Valuable genes often spread readily from population to population and selection is for gene ow of such genes c While genes useful only within the local population will tend not to flow to other populations are selected against in other populations Condition 111 N0 mutations may occur a This is a violation because each mutation represents a new allele so changes gene frequency by that new allele Note this is a brand new gene a source of novelties which happens all the time b DNA is continually being bombarded by UV cosmic rays mutagenic chemicals etc While per gene there is a low frequency of mutations 106 per individual but as there are about 106 genes per individual then a new mutation occurs in each of us every generation c However such mutations are generally disadvantageous detrimental and are rarely good or beneficial d Think of an organism as being a finely tuned machine 7 like your TV set7 shooting at it with a 22 ri e is not likely to make it work better e Small changes are therefore much more likely to advantageous than big changes Macromutations have only a remote tiny chance of being useful Hopeful monsters are not likely f Genetic load is the accumulation of recessive deleterious genes because the diploid condition hides them however such genes might be valuable under other environmental conditions V Random mating random survival random reproduction must occur This is the most important condition Its violation results in selection both natural and artificial If a gene is favorable even 110 of 1 better it will very likely increase in frequency or if similarly unfavorable it will very likely decrease in frequency that is be selected for or against Condition 1 a b E Fitness 1 Again note tness is not defined as the largest strongest or most intelligent or most healthy but instead in terms of reproductive success in producing the next generation 2 Darwinian Fitness is measured by reproductive success of individuals that leave progeny that reproduce Obviously an individual organism must survive to reproduce and reproduce more than other individuals Another way of stating this is positive differential reproduction of some phenotypes 3 Inclusive Fitness is the success of the gene itself in promoting its own reproduction a Think of the adult as being the gene s way of making more copies of itself or the chicken is the egg s way of making more eggs b This helps to explain altruism in which individuals endanger themselves reducing their Darwinian fitness but enhancing their inclusive fitness 4 Kin selection is a selfish altruism a Take a pack of wolves in which the alpha female and the alpha male reproduces but others in the pack do not the other members of the pack being related to the female enhance their own genes intrinsic fitness by being helpers in raising the litter of pups This is seen in a number of species as the Florida Scrub Jay and blackbacked Jackel see Smiths pages 366368 b Another example are the social insects as the ant bees wasps and termites in which only the queen reproduces and the others the workers benefit their genes through the queen So if a bee stings you and dies but makes you run away she has favored her genes because she has protected her mother the Queen who is likely making copies of the genes occurring in workers c Think of the deer signaling danger by lifting her tail the crow calling out at the sight of a hunter all endangering themselves for the social group their kin 4 Reciprocal selection This is not common Here unrelated organisms band together for mutual defense and mutual support for reproduction This then represents a social contract Man seems to be the best example of this Social groups benefit by making it difficult for predators to attack All social groups must benefit from being together for this indicates past selection 5 Group selection Some evolutionary biologists think little of this idea that a group of organisms compete against other groups of organisms of the same species Perhaps man does Smiths discuss this subject in detail and it forms an argument for the evolution of social behavior as pitting one group s success against another F Types of Selection See Fig 199 in Smiths l Directional selection a Changes in gene frequencies that represents adaptive evolutionary change in which changes in the environment favors gene combinations away from the mean are selected for b A famous example is Industrial Melanism Biston betularia is a moth studied by Kettlewell He demonstrated experimentally that birds were eating the moths that were resting on the bark of trees and that the black carbonaria forms were protectively colored resting on trees that had black bark because air pollution had killed the lichens c Think of all the insects and microbes that have evolved resistance to insecticides and antibiotics respectively This represents Natural Selection is at work 2 Stabilizing Selection a This the most common selection in that it is maintaining a good combination of genes adapted to the physical and biological environment Permanent little changing environments promote maintaining the mean gene frequencies the best average to promote survival and reproduction A good example is the emergence of periodical cicadas These insects emerge every 13 or 17 years in broods It is highly predictable when a brood emerges Careful studies show that the cicada emergence time is maintained by stabilizing selection Those that emerge early are eaten by an army of predators those emerging late are eaten by the predators that have digested their meals Thus those that emerge on time reproduce Most evolution is running hard Like the Red Queen to maintain the best I 39 to the 39 39 all the variation generated by sexual reproduction Only a few genotypes would survive to reproduce these being most likely best adapted to the habitat Selection does get rid of deleterious mutations but slowly because most mutations are recessive and remain in very low frequencies Good genes are amplified in frequency by natural selection Electrophoresis has revealed that there is very high heterozygosity in most species Probably the heterozygote is in generally superior a phenomenon called heterosis or hybrid vigor Selection and outbreeding evidently maintains heterozygosity This helps to explain the many adaptations for dispersal to new areas new mates 3 Disruptive selection for more than one form a polymorphism a One type of polymorphism is in gene expression where di erent genes function as in male and female sexes in social insect castes as in workers soldiers queens etc but the same genes are present in each individual different ones are expressed U 0 Q D Fquot Another type is where in the population two dyfkrent adaptive peaks are selected that are genetically different Cegaea snails in England have brown white and banded forms This is partly due to protective coloration against back grounds of brown forest white chalk soil and grassland the latter favoring banded snails and partly due to English Robin their main predator forming search images finding and eating one color morph and ignoring the others d Another example is Pagilio dardanus where the male is one morph and the females show three morphs each mimicking a different poisonous butter y This kind of mimicry is common in the tropics Sickle cell anemia of West Africans is an example of a balanced polymorphism where the homozygote for normal hemoglobin is susceptible to malaria the homozygote mutant hemoglobin causes the lethal sickle cell condition but the heterozygote survives because while not as healthy it is resistant to Malaria Both homozygotes are necessary to have the heterozygote that survives best C d G Importance of population size Smiths 369379 1 Chance changes gene frequency as noted occur in small population causing nonadaptive genetic drift 2 Inbreeding tends to occur in small populations which is genetically dangerous because it promotes homozygosity causing an inbreeding depression a reduction in physiological vigor reduced 1 r J 39 poor 3 39 1 measures this reduction in heterozygosity in populations The Fixation index 3 The Cheetah shows strong evidence that at one time its populations were severely reduced causing a genetic bottle neck of very small population size because the populations show high 1 J g i 39 39 39 quot weakness 4 V39 0 y and I and r This pattern is reproducing itself as the result of the reduction in population size of many modern mammals The Thar Desert population of the Asiatic Lion is very small and is now undergoing genetic collapse Another similar example is the isolated Ngorongoro Crater population of lions discussed in Smiths pg 372 As habitats are destroyed by man and species become restricted to isolated small patches inbreeding becomes a danger especially for large vertebrates which require a lot of space and so tend to have small populations This is a big problem for natural reserves Thus there is a lot of discussion as in Smiths about this practical problem often involving endangered species Unusual is an outbreeding depression This is caused by introductions into a population of individuals from other areas that are genetically very different Probably in the other area the species is subjected to different selection producing gene combinations that do not fit well into another population indeed may be in process of speciating Care must be taken on introductions Effective population size measures effect of deviation from randomness in reduction of number of males One to One male and female is ideal a In species that have a harem social system the number of males contributing to the next generation is reduced so population sizes need to be greater b Smiths pg 357 give the formula for calculating the effective population size needed to maintain genetic vigor Hunting that reduces the number of males 9 results in a similar pattern plus there is strong selection by human hunting against strong bucks with good rack of horns for trophies unfortunately Genetically it would be better to hunt spikes c Subpopulations neighborhood size are affected by amount of dispersal and isolation for gene ow in the species Minimum Viable population is a speciesspecific estimate of the population size required to ensure survival of a healthy population and to avoiding inbreed As Smiths discusses the 50500 rule subpopulation total population has been applied but this generalization does not work for all species and is dangerous to use without careful study of the species in consideration IV Oceanic Environments A Introduction 1 This is the enormous extent of water off the continental shelf 2 As described the ocean zonation by depth is as follows P 43 0 2391 FD a Illuminated epipelagic extends down to the compensation level which in oceanic area is very deep to 200 M because the turbidity is very low The fairly warm mesopelagic extends down to 1000 M or in the tropics to the 10 C isotherm it is high in nutrients but low in oxygen due to the high BOD from the rain of productivity from the epipelagic The cool bathypelagic extends down to 4000 M in the tropics to the 4 C isotherm The average depth of the oceans is about 3800 M The cold abyssopelagic which is below 4000 M and 4 C in the tropics is the water over the ocean basins In water of oceanic salinity 35 000 the coldest water is the heaviest Hadopelagic water is the water below 6000 M which extends into the trenches where the heaviest water is below 4 C The deepest trench is in the Marianas 10 803 M deep 3 The benthic habitats underlying these waters are the bathyl Archibenthic on the continental slopes the abyssal and the hadal zones There are also slopes from magma upwelling ridges and volcanic islands some of which develop evidently developed from a single hot spot B Plankton 7 from hotspots where magma flows up as in the Hawaiian Island chain that Many of these organisms may be unfamiliar to you but these organisms are very important in the marine biochore and by extension for Planet Earth s life support system on which you are ultimately dependent See P 44 and pgs 670676 in Smiths for illustrations of these organisms 1 Life Cycles a Meroplankton part of life cycle in plankton 7 These are largely larvae and are most abundant in the Neritic zone because the larvae can swim to the bottom to metamorphose into the benthic adult form Remember that organisms in the sea disperse through the water column so planktonic larvae are very important b Holoplankton live entire life in plankton 7 These are in all marine habitats but are the most important in the Oceanic Zone c Most algae as single celled plants are holoplankton with exception of some coccolithophorids 2 Phytoplankton Net plankton gt 60 microns Microplankton is 20 to 200 microns and includes diatoms and dino agellates Nannoplankton is 02 to 20 microns and includes coccolitho agellates and small phyto agellates that mostly go through a plankton net The picoplankton range from 002 to 02 microns and includes very small eukaryotes and the bacteria including Cyanobacteria a Diatoms 7 These are especially abundant in cold Arctic areas 7 they have siliceous cell walls called frustules and being like glass are heavy b Dino agellates have cellulose cell walls are lighter and dominate warm water c Coccolithophorids are abundant in tropical temperate areas They make their cell walls of calcium carbonate plates which are like overlapping shields These organisms are very important in removing Calcium carbonate from the water and so are important regulators of the C02 levels in seawater and ultimately of the atmosphere d Minute green agellates 7 no protective skeleton pass through plankton net 7nanno and picophytoplankton e For example is Chromulina pusilla lt 15 microns has 1 chloroplast l mitochondrion and l nucleus cannot be any smaller and be a eukaryotic alga It falls in the picophytoplankton f 90 of phytoplankton of tropical waters goes through ne silk mesh of 1000mm2 even 40 of phytoplankton through Whatman lter paper 3 Sargassum a brown seaweed is a oating community that could be called planktonic in the broad sense 7 remarkable community and the word pleuston that is used in freshwater ecology for algae mats would t here C Zooplankton Holoplankton See P44 in class notes and g 318 in Smiths l Copepods and euphausians are very abundant microcrustaceans that lter feed on phytoplankton 2 Foraminiferans and radiolarians 7 amoeboid protozoans that catch microbes and organic particles with long pseudopodia LA 4 UI 0 gt1 a Forarniniferans build tests of calcium carbonate A common genus is Globigerina which so abundant that its tests form calcareous oozes b Similarly radiolarians build beautiful glass tests of silica which can be so abundant that extensive oozes are formed of these glass tests Pteropods 7 butter y mollusks 7 are modified gastropods that swim using their modi ed foot Some have a shell and can be so abundant as to form pteropod oozes Chaetognaths 7 arrow worms 7 are shlike invertebrate predators that can even eat small herrings and are themselves fed on by large sh Ctenophores comb jellies are common carnivores on planktonic copepods Many are beautiful and bioluminescence Cnidarian Medusae jelly sh and the colonial siphonophores like Portuguese manowar are important predators in the plankton Tunicates Phylum Chordata subphylulm Urochordata are abundant a Oikopleura Class Larvacea 7 The class which is especially common in cold water are solitary lter feeders on nannoplankton Resembles a tadpole larva of a benthic tunicate b Doliolum Class Thaliacea 7 This class includes barrellike colonial tunicates which lter feeds and are especially common in tropical waters These are often called salps and many bioluminescent such as Pyrosoma D Zooplankton meroplankton 7 These are especially abundant in the Neritic Zone as the N E larvae in the plankton can reach the bottom to metamorphose Recall that marine organisms disperse through the water column Some common larvae are given below The nauplius larva of many crustaceans The larva goes through several stages before transforming into adult form Echinoderm larvae are of several types corresponding to the echinoderm classes Trochophore larvae of polychaetes mollusks and other invertebrates are abundant in the plankton Benthic tunicates have tadpole larva of that are benthic some solitary others colonial 5 Cnidarian planula hatch from eggs and small medusae of hydrozoans are common in the plankton Some alternate between polyps and medusae The Ctenophora Comb jellies have cydippid larvae 6 Fish eggs and larvae7the larval Leptocephali look very different from eels E Bacteria of the picoplankton are important in the cycling of organic matter and nutrients microbial loops feeding back to the phytoplankton and returning the nutrients to the food chain see fig3l9 and 3112 in Smiths Note these bacteria are not chemosynthetic so cannot be considered primary producers are suggested by the Smiths but are consumers F Nekton of Oceanic Zone7domain of sh and squid l Epipelagic fish shrimp squid mammals graze on zooplankton a You know the plight of the whales many species are now being fished into near extinction b Also but not so well known is that many fishes are also being very overfished7 species like cod now becoming endangered c The sea is not a cornucopia for most of the seas are biological deserts due to the lack of nutrients d Only in cold upwelling areas is the oceanic zone productive in the plankton that nourishes the top carnivores that we eat e Because big carnivorous fish at the end of long food chains a serious problem is the concentration of heavy metals like mercury our pollution in the esh of such fish So much so that nutritionists are recommending that the consumption of tuna be limited yet the important essential omega3 fats are most abundant in these fish The omega3 fat incidentally ultimately comes from the planktonic algae Animals cannot make omega3 fats despite how important they are for synthesizing healthy cell membranes 2 In Disphotic Zone of the mesopelagic 7 only very dim light is present a Mostly mall nekton live 7 many weird fish and other animals b Luminescent organs and large eyes or minute eyes are common c Giant squid that are fed on by sperm whales live here d A false bottom is sometimes detected by sonar 7 turns out to be a deepsea scattering layer composed of organisms e Animals captured in deep water are killed by heat shock and change in salinity of the water not the change in pressure as is commonly thought G Benthic Zones of the oceanic area 1 Because there is little turbidity from terrestrial sources the bottom of deep ocean has oozes derived from to dominant plankters with hard parts In water deeper than 4000 M CaC03 goes back into solution due to pressure a Diatomaceous ooze 7 cold water b Radiolarian oozes 7 cold water c Globigerina 7 foraminiferan ooze 7 wa1m water d Coccolithophore oozes are also found in warm water Removal by coccolithophorids of CaCO3 is now recognized as being very important for C02 regulation in the atmosphere e In a few places in very deep water only red clay oozes derived ultimately from land are found N Animals a Very diverse7many species live in the Bathyl or Archibenthic Zone See P 43a many of which are meiofauna very small in size Although food diminishes the respiration rate drops in response to increasing pressure and to the cold water so the need for food b Glass sponges are especially common and some are very beautiful as is Venus s 7 ower basket Glass sponges are rare in the shallow waters of the Neritic Zone c Many 39 39 J ms 1 39 quotJ the 39 39 quot 391 sea cucumbers serpent stars and crinoids sea lilies both stalked and swimming are common d There are many crustaceans sponges bivalves and gastropods Neopz39lina of the molluscan Class Monoplacophora which was known as fossil up to the Devonian appeared in the present an example of why the bathyl zone is called the Archibenthic e Pogonophorans are common in deepsea benthos f Short nonplanktonic larva life is common in deep sea as the animals are far from the surface g The strange Holocephali of Chondrichthyes are characteristic of deep sea h Much less diverse below 4000 Meters 7 this is perhaps a consequence ofthe cold of the Pleistocene ice ages as it is recent Mesozoic waters had wa1mer deep waters much like slope water today i Animals become less and less frequent in deeper water of the Abyssal and Hadal zones but they are there even in trenches of the Hadal zone H Deep Sea Hydrothermal Vent Biota along ridges of uprising magma Fig 3110 in Smiths 1 Amazing oases in the deep sea based on thermal heat from volcanism 7 overall water is 8 to 16 C in the vent area as compared to 2 C surrounding deep water N Jets of water issue from ssures with water temperatures reaching 300 to 450 C 7 great pressure prevents boiling Chemosynthetic bacteria live and metabolize in this superheated watergextremophiles E Water rich in HZS and sul des that are used as energy source by sulfur bacteria Deposition of minerals creates white and black smokers 5 The chemosynthetic bacteria nourish a compleX assemblage of animals including giant clams that lter bacteria and vestimentiferan worms Riftz39a a new class of the Phylum Pogonophora that have living in their coelomic tissues symbiotic bacteria that metabolize reduced sul des A total of three new orders and 22 new families of animals were found in the vent biota Of the 293 species found 97 were endemic to the vents How poorly known is the deep sea V Neritic Environments See P 43 in Class Notes A Introduction 1 Includes the marine water from the low tide line to the margin of the continental shelf 2 And the bottom communities underlying this is the sublittoralz which is in turn a Divided into the infralittoral zone or scuba zone characterized by the presence of attached algae down to usually about 50 meters more or less indicating light suf cient for photosynthesis reaching the bottom This is also called the inner sublittoral or the subtidal zone b The circumlittoral or outer sublittoral is non sunlit bottom that extends out to about 200 meters down to the margin of the continental shelf c The water of the Neritic is often called Neritopelagic zone as distinguished from the oceanic zone 3 The sublittoral zone is divided into distinct benthic types on the basis of the type of bottom 7 maybe terrestrial origin or some of biological origin like shells or coral sand See list on P 47 in class notes B Soft bottoms mud sand or coral sand of the sublittoral 1 These habitats are dominated by a benthic fauna lter feedis on the plankton and deposit feed on detritus a A great variety of clams Pelecypoda that universally lter feed And often burrow in the substrate with siphons out to draw water in and eXpell it b Some gastropods like Olivia Olive Shell Polim39ces Moon Shell and Busycon whelk burrow into the sand and mud searching for and feeding on clams They drill a hole into the clam to feed on it When the gastropod dies the shell is usually exploited by hermit crabs for a home Often on the shells grow colonies of bryozoans hydroids tunicates sponges c Polychaete Utube dwelling worms are abundant and most like Diopatra feed by filter feeding Little peacrabs are often found in the burrows d Epifauna of sand dollars and serpent stars pycnogonids sea spiders etc 2 Silversides fish 7 live in turbulent sandy surf 3 Species differ according to bottom type wave action salinity 4 If shells algae attached to them as a convenient hold fast C Hard bottoms cool water in rocky areas 1 Dominated by epifauna 7 very rich 2 Many attached animals like bryozoans sea anemones hydroids corals benthic tunicates oysters Ostrea in full salinity and C rassostrea in brackish water 3 Creeping forms like gastropods sea urchins and starfishes 4 Infauna of little invertebrates live in crevices among rocks and shells E Large array of fish live in the nekton or Neritopelagic zone 1 Herring fishesiClupeidaeuherring menhaden sardine and anchovy ilarge feeders on the zooplankton 2 Schooling tendency among these fishes probably defense against larger fish birds and Mammals 3 Many show definite migrations North and South with seasons 4 Cod haddock pollack ounder soles and halibut are benthic feeders 5 Salmons are anadromous return to freshwater to spawn and return to sea to fatten 6 Mackerel and tuna 7 later in life become oceanic type shes feeding in the plankton 7 Many of the fishes begin life in shallow water in bays and marshes This is very important for fishes as nutrients wash in from land and nourish the bays and marshes VI Littoral and Subtidal Environments A Introduction This is the great ecotone of where the marine environment meets the terrestrial and freshwater environments These are complex situations where ecosystems interact with each other a focus oflandscape ecology 1 Meeting with the freshwater environments at the mouth of rivers Estuaries or estuarine where the mixing is in lagoons 2 Meeting with the terrestrial environment Littoral Zone7May be rocky sandy or muddy bottoms depending on the amount of energy from wave action 3 In quiet waters find quotsea grassesquot 7 in lagoons for example with a rich associated fauna B The Rocky Shore Fig 3115 in Smiths l The richest marine shore habitat is where there is a hard substrate for organisms to attach 2 Along the Texas Gulf Coast such firm shoreline habitats were originally virtually absent except for oyster reefs which however are in brackish water of estuaries and lagoons 3 However hard bottoms have been arti cially supplied in the jetties groins and piers along the coast These are best seen at low tide especially when an offshore wind blows the water off the shore Also at low tide the surf tends to be least because of momentum changes Your textbook by Smith describes the intertidal zonation as it occurs on a rocky coast in New England or Europe Below are mentioned major organisms on the Texas Coast Jetties The remarkable thing about this fauna is that it represents long distance dispersal of these organisms from hard surfaces elsewhere in the Gulf or the Caribbean 4 Supralittoral 7 the spray zone or littoral fringe caused by wave action a Normally on rocks and boulders we find a saltadapted lichen ora like Verrucaria along with bluegreen algae which forms the black fringe which when wet is so very slippery because of their gelatinous sheaths b On this ora at storm tides on northern coasts graze periwinkles Littorz39na which are able to fix themselves to rocks and wait for the next episode of surf When the tide recedes and the habitat dries out then appears the insects and the sea roach Ligia an isopod that feeds on the algae 5 Upper Littoral Zone a Barnacles are most distinctiveiChthamalus is the highest in the intertidal as it handles dehydration well and often essentially lives in the supralittoral Most coastlines world over has Chthamalus in the upper zone b In Texas the false limpets Sz39phonaria and ZicZac periwinkles occur with C hthamalus These organisms are adapted to the surf of this habitat by being like tanks tough and hard to withstand the force of the waves c Enteromorpha like intestines is abundant in the upper zone in sea spray Such delicate looking algae and other algae deeper in the water handle the pounding surf by being exible giving with the water not resisting it 6 Littoral Zone Mid 0r Eulittoral Zone is always covered and exposed by the tides a On our coast in relatively brackish water this zone is characterized by oysters being attached The oysters actually do well in full marine water but cannot handle predation and diseases so they escape to brackish water and survive by leaving their enemies behind Texas coastal shores tend to have lower salinities so the oysters can survive but in dry spells the salinity increases and the oysters die back from predation and diseases The red and brown seaweeds tend to be more common in the winter months b Thais oyster drill a snail that feeds on oysters is a common example of such a predator It cannot live in lower salinity water like the oyster c On colder shorelines 7 F ucus and Ascophyllum attached brown rock seaweeds would be abundant here d Sea lettuce Ulva and more Enteromorpha are common green seaweeds here Many red algae appear here such as sea lavender Porphyra and Gracilaria e A great variety of attached animals like mussels which on colder shores are thickly colonized by blue mussels bryozoans lace animals or moss animals serpulid worms that make calcareous tubes and hydroids colonial cnidarians that make slender colonies sponges and tunicates f Molluscan limpets and slipper shells are not attached but cling tightly to the rocks where they scrape the algae Crepidulafornicata is remarkable in that the animals cling to each other one on top of the other with the smallest on top The small top ones are males and the larger ones are female As the slipper shell grows larger it transforms into a female Crepidula often attaches itself to another mollusk Some are motile such as crustaceans like the hermit crabs that live in the shells of gastropod mollusks stone crab Menippe and Caprella the skeleton amphipod Other small amphipods and isopods are found on the algae and little shes as gobies and blennies swim about in the turbulent water 7 Lower littoral fabundance of many genera of red algae a The lower tidal margin is marked by sea urchins Arbacia and anemones Bunodosoma A different bamacle Balanus occurs here that out competes Chthamalusand so restricts Chthamalus to the high tide area There are only a few small brown algae in Texas notably Dictyota and Padina but the large kelps that makes the algal forests seen on cold coast lines in the Northeast and on the West coast of North America and as pictured in Fig 3115 in Smiths are absent on the Gulf coast 8 Especially characteristic of rocky coastlines are tide pools where water is left behind by the low tides and recaptured by the high tides a Tide pools is often like outdoor aquaria with a variety of interesting organisms living in them The larger intertidal tide pools that are permanent depressions covered with every tide a have a sublittoral fauna in an outdoor aquarium so to speak In California so great is the impact of humanity that it is outlawed to collect organisms from the tide pools b Tide pools at upper limit often have wildly uctuating conditions of salinity heat and also chemical conditions such as from the fertilizer of bird droppings c Tide pools in Texas are actually storm pools especially on the jetties There are often brackish pools and ponds on the Barrier Island and marshes that are replenished by strong storms then freshened by rain These can be biologically very rich 9 Importance of attached macroscopic algae the seaweeds a 0 Sequence of attached algae Greenigt Brownigt Red algae in the deepest water This is related to absorption of light by water Algae have accessory pigments that absorb other wavelengths Green algae are normal in that blue and red to infrared are absorbed green re ected As red is not available the pigments absorb green 7 Brown algae As red is not absorbed absent in deep water ialgae appear red pigments are absorbing other colors green and yellow re ecting red Browns in cold water frequently form kelp forests Laminaria on East Coast is up to 12 feet long and on the West Coast Macrocystis and Nereocystis can be at least 30 and maybe up to 300 feet long Such algal forests act as a breakwater and reduce the force of the waves greatly d The giant algae form attachment sites for a large number of animals and algae The kelps are fed on by sea urchins on the west coasts and the sea urchins are kept in check by sea otters With the over harvesting of the otters by man there has been a overpopulation of sea urchins leading to a collapse of the kelp forest ecosystem so strong efforts have been made to bring back the sea otters This is another example of the importance of a top carnivore keystone species Recall Paine s work on the importance of the big star sh Piaster on the rocky shore communities in Washington C The coral reefs of tropical areas are the richest of marine ecosystems These are hard bottoms dominated and created by coral animals and coralline algae this is an enormous biological community comparable to the tropical rainforest in diversity and complexity and for largely the same reason having a high biomass structure where many different species large and small can live See P 46a and P 46b 1 Coral reefs do not normally form in waters colder than 20 C in winter rarely lower as18 C at Bermuda and S Floridaiand are best at 23 725 C While calcareous corals and algae occur at cooler temperatures no reefs are found Also no reefs grow in dark deeper water Why is Coral reef growth is restricted to sunlit water 2 The tropical seas are biological deserts because of a lack of nutrients How then can the coral reefbe an oasis ofthe sea a Both calcareous red algae and coral animals build the reef Reefbuilding corals differ from other corals b The coral animals of the reef themselves contain zooxanthellae actually dino agellates that consume coral animal waste products c Coral animals are all zooplankton feeders specialized camivoresirapid digestioniwaste NH3 and phosphate goes to nourish the zooxanthellae This concentrates the nutrients in the reef ecosystem creating recycling of nutrients that allows the incredible growth and diversity in the coral reef d The zooxanthellae algae pass carbohydrates to corals and modify chemical conditions which allows the coral animals to lay down Calcium Carbonate abundantly e Red Calcareous Algae Lithothamnion and Porolithon actually grow in teeth of the breakers and are important parts of the coral reefs Roughly 34 of a big reef is plant materialmf which the zooxanthellaedino agellates contain 13 but the reef requires the coral animals for normal growth and stability quot1 3 There is a marvelous series of color and form making up the corals of many genera a Branched forms like Acropora and massive forms like Porites 5 V39 9 gt1 9 D l 5 b The richest reefs are in IndoPacific rather poorer reefs are in the AtlanticCaribbean Associated are attached or semiattached animals like sea urchins and in the Paci c the giant clams Tridacna and giant sea anemones are abundant There is a remarkable abundance different invertebrates and a high species diversity Fish are of enormous variety and very highly coloredimost of these graze on algae and coral Some live with other organisms even inside anemones and sea cucumbers as commensals or mutualists Barrier reefs along continental margins fringing reefs around island and atolls surround a lagooniDarwin s subsidence theory as to the origin of atolls due to the subsidence of a volcanic island is essentially correct as is shown by drilling on Midway atoll in the Paci c Another danger is more insidious Global warming The danger is that the seas can rise so rapidly due to the melting of the ice and the thermal expansion of water that the coral reefs cannot grow fast enough to keep up with the rise in sea level and will get overwhelmed Indeed in Polynesia there are whole nations living on atolls that are in danger of extinction from global warming However coral reefs are extremely vulnerable to pollution of all kinds Many reefs are highly endangered including the coral reefs off Florida near Key West Many others are drastically endangered by dynamiting and the use of cyanide to capture coral reef fishes for the salt water aquarium fish trade Estuaries Any cursory study of a map shows coastlines of very different configurations frequently we find deep indentations and wide river mouths forming deep estuaries these result when there has been a marked subsidence of land or rise of water so that the river mouths are drowned these are classified as quotyoungquot estuaries Rapid emergence of land and subsidence of sea bottom areasmountains go down to sea to produce smooth shorelines with very few bays or large estuaries and deltas are poorly developed as off the West Coast of North America and produce rocky seashore with cliffs In contrast we may find a low at land plain with a smooth shoreline in which the rivers empty directly into the sea and deltas are being formed and an extensive series of offshore barrier islands are being formedithese are usually evidence of land emergenceor quotoldquot estuaries Sometimes low at plains may submerge again drowning shallow river mouths producing barrier islands and lagoons due to drowned river mouths as in Texas Gulf and US East Coast When the river ends at the sea in a quotnew estuary quotwhich is really an aim of the sea it dumps sediments at the mouth of the river which shortening the estuary a Likewise erosion by waves and tidal currents deposit ne materials at the mouth making the estuary shallower U Eventually the ne mud sediment builds up to form a mud at exposed at low tide producing braided channels 0 Eventually the sediments build out into the ocean to form a delta in which case the estuary becomes the actual water pouring into the ocean over the bed of its sediments We may see this admirably at the mouth of the Mississippi which is one of the world39s famous deltas Other famous deltas are the Nile the Amazon and the Ganges 5 The estuary is a dif cult and drastic osmotic environment that varies with tidal rhythms winds oods and droughts that affect river ow 6 Since saltwater is heavier freshwater moves over the top and saltwater moves in along the bottom creating a highly varying vertical strati cation of fresh water over salt water in the estuary 7 Because of constant supply of nitrates and phosphates from land the estuary is rich in nutrients and it is very productive despite being a dif cult environment 8 Because it is a rich but dif cult environment there may be relatively few species but the species present may be very abundant 9 Very few freshwater animals mostly marineiEuryhaline species 10 Many marine shes spend early life in estuarine environment nurseries before moving out into sea to maturate 11 Oyster beds and reefs are important communities that often form transversely to the ow of tidal water in estuaries and are a result of oysters growing on oysters for many hundreds of years These reefs have a rich epifauna of mollusks algae sponges worms growing on them or associated with them Recall that the word biocoenosis was inspired by the study of an oyster reef in the North Sea by Mobius D Lagoons are largely cut off from ocean and may be either brackish in rainy climates or very haline in dry climates Both can occur in Texas but usually treated as estuarine environments and can resemble shallow estuaries discussed above 1 An effect of the depositions of sand and silt from rivers combined with current action is the formation of offshore barrier islands that enclose lagoonsquiet water This is very common along low coastal plains with shallow off shore waters N Laguna Madre of South Texas maybe hypersaline with up to 80 000 of salt LA The same lagoon may be very brackish if input of freshwater is high It can become a bay favorable for mosquitoes and other freshwater animals 4 In Baffin Bay Texas when heavy rains broke a drought salinities were reduced from 60 000 to only 2 000 5 Lagoons like estuaries are often rich environment due to nutrients supplied from rivers and oceans and from the productivity in the salt marshes creating nursery environments for shrimp and fish 6 Sea beds or meadows are formed by vascular plants growing in the lagoon salt water Turtle grass Thallasia Manatee grass Cymodocea Shoal grass Halodule Eel grass Zostera and others These communities form very rich ecosystems in the lagoons E Salt Marshes and Mud ats l Wherever sheltered from wave action as in a lagoon f1ne mud of silt can be deposited This is especially true in estuarine environments cut off from the sea 2 These habitats are invaded by a group of saltadapted vascular plants originally from land that can root in the mud and extend their leaves into the air A rich habitat if the plant can handle the saline habitat which can vary from hyposaline to hypersaline 3 The animal and plankton communities in the mud at show predominance of marine species in contrast to the plants Many f1ddler crabs and snails live here 4 Plants in the salt marshes in Texas a Dominant grass at edge of water is Spartz39na alterm39 ora cord grass b Away from edge in the ats is low Spartz39na patens salt meadow hay or cord grass c Slightly higher in the high marsh is Juncus roemeranus Black grass and Distichlis spicata and Spartz39na spartinae and a variety of saltadapted plants d In salt marshes often nd pools or muddy spots called pansiwidgeon grass Ruggia maritima is common here e Most of the salt marsh dicots are succulents with thick leaves and or stems like Salicorm39a glass wort 7 pioneer plant f The marsh is a physiological desert as the plants are hypotonic as compared to the water which can become hypersaline in times of drought so this is a very tough environment to withstand 5 Tidal creeks drain marshes at low tide with steep mud banks There is a rich algae ora of diatoms and dino agellates in the creek Cyprinodont shes and grass shrimp Palaemonetes are common inhabitants of the tidal creeks 0 Animal inhabitants include infauna ofworms ribbed mussels M odiolus razor clams Ensis and other clams as well as ddler crabs Uca that live in burrows in the mud Aquatic insects including the salt marsh mosquitoes can be abundant in the salt marsh gt1 This is a very important nursery environment for young sh and shrimp Safety and food are found in the salt marshes Also it is a mecca for water birds ducks geese stems gulls wading birds sparrows etc feeding on the rich plant and animal life gt1 However this rich environment is rapidly being destroyed by people through pollution housing developments dump piles etc This poses a dif cult economic con ict The juvenile shrimp and the sh will of commercial importance as food when they grow up Yet landowners need to pay taxes as well as want to make money and many wish to live there F Mangrove Swamps 1 Because like corals mangroves cannot survive moderate cold they are restricted to warm climates 2 The tropical mangroves are series of unrelated trees that can grow in salt marshes some even in open water below low tide mark and undergo an ecological succession replacing the herbaceous plants of the marsh with woody plants of the mangrove swamps Mangroves are characterized by many prop roots that support the plant in the mud 3 In Florida and the Caribbean red mangrove Rhizophora has large stiltlike prop roots and forms large seeds that sprout on the trees and drop off and oat in water to grow immediately into mud when it is contacted 4 Black mangrove Avicennia replaces red mangrove at high tide The Black mangrove has pneumatophores Avicennia occurs along Laguna Madre where it is often frost damaged and can only grow to be a small shrub in the salt marsh Higher up in neotropical areas occur the white and button mangroves 5 The mangroves are important for maintaining shoreline building new land and preventing erosion G Sandy shore 7 Increasing energy from wave action suspends ne silt and clay leaving sand to settle out The barrier islands are formed from sand from land carried long shore by currents and built up by wind blowing the sand exposed P 47 in class notes shows a cross section of the sandy barrier island a good example of a compleX landscape ecosystem 1 This is an ecosystem on the move because the sand is constantly shifting both in the water and on land N 4 V39 0 gt1 Along rocky seashores there is often a transition between the rocky headlands where the waves smash and a cove where a pocket beach is found from rock to cobblestones to pebbles to sand Areas as in Texas where the coast is a lowlying plain the seacoast develops a landscape dominated by sandy beaches facing the sea often on barrier lands with a lagoon of quiet water behind it which was just discussed in the context of estuarine environments In these sandy beaches P45 and 3121 in Smiths wave action is very important The waves are oscillations of the water up and down swells created by the wind pg 688 in Smiths When the underside of the oscillation hits the bottom it causes the top water to topple over creating the surf familiar to one at sea shores The biggest waves break the further out and the smaller waves break more inshore This causes on sandy shore the characteristic pattern of a series of sand bars off shore This wave of surf progresses toward the shore to break on the shore NOTE this surf is not the tide The tide is the overall raising and lowering of the water level which however affects where the wave breaks All this mechanical action puts sand grains into the water turbulence creating an ecosystem very much on the move Microscopic organisms living between sand grains are called the psammon It consists of microbes and the little animals that can live interstitially between the sand grains The community of sand is dependent on two sources of nutrition a First the particulate organic matter and the bacteria associated with it 7 there is a rich unseen bacterial biota The organic matter comes mostly from salt marshes and other vascular plant material See Smiths Figs 319 and 3122 6 Second the diatoms and dino agellates of the psammon are abundant producers which survive in this environment by rising to the surface at low tide and sinking into sand at high tide to resist being washed away The animal life in sand may be divided into several classes depending on habits and nutrition 2 Small scrapers of the meiofauna like copepods and nematodes that fed on algae and particulate organic matter on the sand grains Much of the organic matter comes from the salt marsh community or the terrestrial environment Fquot Active burrowers called endopsammon or infauna like the polychaete lugworms Arem39cola which literally may eat the substrate to digest the food available in he sand Many other polychaetes live here like Diopatra which is tubebuilder that filter feeds and Nereis that is a predator 0 The sand sorters as the many tube dwelling polychaetes that use their tentacles to search for food particles d Another important group of sand sorters are the intertidal crustacean amphipods of he genus H austorius H austorius swims in the surf as the tide comes in and burrows in the sand as the water leaves thus maintains it position in the surf Haustorius feeds on organic particles clinging to the sand grains e The ghost or snapping shrimp comes out at high tide and shifts through the sand grains for organic detritus These have a modified claw that makes a loud snapping sound f The next groupof animals filters the particles of food from the surf watersithese are bivalves like the cockle C ardium which has a fairly permanent burrow and Donax the coquina clam which feeds at high tide in the moving tidal waters Emerita is the mole crab which lives in burrows and strains food out of water with its antennae g Further out on the sand of the bars are epifauna like sand dollars and serpent stars that sort for particulate food on the surface Renilla the sea pansy and Leptogorgia the sea whip have a foot in the sand and as soft corals have little polyps that capture food such as copepods from the water Along with these are found the predators such as E The active polychaetes like Nereis U Nemerteans the ribbon worms use their proboscis to snare prey The gastropods Policines Moonshells Busycon whelks and Olivia Olive shell that burrow in the sand and feed on clams W The swimming crabs blue calico and green crabs and the fish killifish and silversides feed in the surf Pquot Gulls and all the shore birds forage on the beaches especially at low tides The abundance of shore birds indicates the richness of this habitat Another big source of food is the washup on the beach especially of the brown seaweed Sargassum and the siphonophore cnidarian Physalia the Portuguesemano war which is food for the animals of the sea shore 0 However the driving of automobiles on the foreshore beach crushes the animals in the sand which is why at the National Seashore on Padre Island driving on the beach is prohibited A little walking to enjoy the beach would never hurt anybody H The sandy beach above the high tide level P 48 l The beach above the high tide markithe supralittoraliis marked by strand of drift left by the tide 2 Slopeithe fore shore is the eulittoral which is tidal everyday with normal astronomical tides 3 Bermithis is the back shore which is formed by storm waves and storm tides 4 Animals of sandy beach 7 extremely difficult environment to live in because of the grinding action of the sand grains and the instability of the substrate 5 The supralittoral is actually terrestrial and inhabited by mixture of organisms mainly arthropods a Talitrid amphipodsi beach hoppers and the ghost crabs of warm temperate and tropical environments live in burrows and forage at night b Many insects especially beetles and ies live in the tide wash on algae and sea grass and on other insects as predators This is a very dif cult environment as it dries out and becomes supersaline and when it rains it becomes freshwater It gets extremely hot during the day in the summer and can freeze in the winter 4 Dunes see P 48 in class notes a Held in place by vegetation7 otherwise the sand would blow away 6 Dominant plants are sea oats Uniola paniculata seaside panic grass Panicum amarum railroad vines Ipomoea Beachtea Croton punctatus Beach primrose Oenothera humz39fusa and many others adapted to living on the dunes Ghost crabs many insects and lizards are adapted to dunes and the coloration and behavior blends them into the sandy background Many especially the ghost crabs dig burrows in the sand The ghost crabs must periodically go to the sea to wet their gills In the tropics there are other land crabs that dominate the shoreline community 0 3 1 Unfortunately the dunes are easily destroyed by thoughtless human intervention4lune buggies etc destroy the plants that hold the dunes This exposes the dune to wind erosion Even worst are homes and resorts built in the dunes h An eroded beach is not only a huge loss of biodiversity but exposes the fragile barrier island to erosion by the sea as well as the wind Important also to realize that the barrier island represents a dynamic situation where the sand brought down by rivers replaces the sand blown away by the wind Damming up rivers prevents sand from going down stream during high waters so the sand cannot replenish the lost sand so the barrier island faces extinction especially if the plants holding the sand are destroyed Hurricanes when they hit also do great damage which is magnified by Man s in uence I If I had my druthers I would make all the barrier islands and lagoons into National Parks and forbid the building of homes resorts and auto traffic on the barrier islands their beaches and dunes and open the barrier islands and lagoons for recreation only that is noninvasive activities on beach and island life like shing walking camping and swimming This complex landscape of interrelated ecosystem is too valuable for the general population for it to be destroyed by the greed of few Think practical think about the sh and shrimp nursery grounds in the salt marshes and lagoons Think of the dif culty living on a barrier island permanently Where do you get good water What do you do with the sewage Put it in the sea Dump it in the lagoon and poison the oyster reeds Think recreation for the people who can do without resorts for the good of the preservation of this beautiful place If you are religious is this not God given Who gives us the right to destroy it Are we not intelligent Are we stewards of our planet Think about it Introduction General A Eco logy House or Household study compare with Economics management of the house 1 Haeckel 1809 in textbook on Zoology invented the word and defined ecology see Smith as follows The body of knowledge concerning the economy of nature the investigation of the total relations of the animal to both its organic amp inorganic environment including above all it s friendly and inimical relations with those animals and plants with which it directly or indirectly comes into contact in a word ecology is the study of all those complex interrelationships referred to by Darwin as the conditions for the struggle for existence A Dane J Warming in Ecological Plant Geography 1895 recognized the word Ecology and gave it broad usage 2 Webster defines ecology as branch of biology that deals with relations between living organisms and their environment that environment including other organisms as well as the physical environment 3 What s the environment Factors that influence the survival growth development reproduction and abundance and distribution of organisms If a factor has no measurable biological effect it is of no ecological importance to organisms 4 The earliest references such as Aristotle and Theophrastus specifically described ecological relationships and it s a very old science in terms of practical applications Smith gives a good discussion of the history of ecology Do not memorize this you will learn about these important ecologists in the context of their work Important not to think of ecology as a frill course or a required filler or an easy course of no consequence I can t think of any subject which so impinges on one s life Let s examine the relation of ecology to biology in general Just as every organism has a structure morphology and function physiology it also has an ecology external physiology that also involves reactions among organisms of same species and among species Idea shown as layers in a cake The slices of the cake would thus represent all the species grouped here by taxonomy as the kingdoms Planta Animalia Fungi Protista and Bacteria In this context remember that each of these species each individual is coded by nucleic acids that program the development of each organism its morphology and physiology Now consider the ultimate purpose of each organism is to reproduce as part of an ecosystem to have a specific ecotope that is a habitat where the species lives in the ecosystem and an ecological niche what the species does in the ecosystem As there are several perhaps 30 million species beside ourselves and each of them is fair game for the ecologist ecology is a wondrously complex field there s no end of things for an ecologist to study Another approach that underlines the position of Ecology among the sciences is to examine its complexity through a hierarchy of subject matter use an overhead Quarks make gt Atoms elements gt molecules gtmacromolecules gt organellesVirus gt cellsSome organisms gt multicelled organism gt populations gtspecies gt communities gt ecosystems gtlandscapes gt biochores gtEcosphere the World Ecosystem B Ecology as a science 1 Science deals with the observable world and is based on curiosity Technology is applied science Science is divided into three parts a What Descriptive structure b How Functional or proximal explanations reductionism view c Why Evolutionary or ultimate explanations holistic view 2 Why bother with science Thomas Huxley who some of you may know as Darwin s bulldog because he enjoyed public debates in contrast to Darwin who was a shy man put it very well It is as if we were all engaged in a cosmic chess game where our opponent nature knows all the rules for us to play the game properly and survive we need to discover the rules Even so we humans often aren t very good about understanding nature through science but tend to resort to superstition and illogical thinking I recommend to you Carl Sagan s last book The demon haunted world for fuller understanding 3 Trouble with ecology is that s so complex and therefore ecological rules to problems require careful holistic approaches 4 Interesting to reflect here that the hard sciences physics and chemistry which seem difficult are actually simple simple enough for mathematical problem solving and therefore tend to emphasize reductionism 5 Solutions to ecological problems are rarely simple in part because in ecology any one thing appears to be stuck to everything else and ecosystems are very complex consisting of hundreds if not thousands of different species interacting with each other show ecosystem But it behooves us to understand ecology because this is our life support system Often an simple but unwise solution may create Ecological Backlashes A good example is the Aswan Dam of Egypt Nile River for millennia had overflowed its banks and renewed the flood plain in the rainy season and provided food for Egypt It seemed a good idea to irrigate the desert But consider the backlashes a food plain is no longer flooded and lost its fertility b Delta lost the new sediments so the delta is eroding rapidly c the fisheries of the eastern end of Mediterranean collapsed through the loss of the nutrients that had nourished the algae that began the food chain leading to fish d due to water loss through evaporation Lake Nasser can never fill and so therefore provides less water down stream for local irrigation e The irrigation of the surrounding desert leads to the salting of the desert soil f Schistosomiasis Bilharzia a blood fluke disease of man exploded in the irrigation ditches that provided an idea habitat for the snails that transmits the fluke Nevertheless we are learning the rules of ecology and as an optimist I believe that it is possible to have good solutions for problems and that we can learn to live with our planet not for a few years or hundreds but for thousands of years we should be stewards not destroyers of our planetll We need an ecological conscience if we are to survive 8 Providing of course we can avoid a Nuclear Holocaust that could end in a blink over 3 billion years of evolution Some of my colleagues are very pessimistic about this and saving the planet saying that we are not mentally equipped to direct the evolutionary play on the ecological theater on our planet We have Old Stone Age brains and customs developed over millennia when humans lived in tiny family units and tribes we didn t evolve to live in giant societies as did the bees and ants and termites One might ask is there really intelligent life on the planet as we destroy our forests erode the soil pollute our rivers seas and air Nevertheless I am optimistic because we really are intelligent and we do have the capacity to be stewards of our planet C Divisions of Ecology Xerox sheet in class notes This should give you an appreciation for the scope of ecology in both pure and applied science D Human Significance 1 Pure Science versus Technology Applied Science in ecology as well greater than most people realize Ecology was once obscure subject as when I went to college Ecology is now conspicuous especially since 1968 when we took the first photos from Apollo of our beautiful blue planet But now we are suffering pollution amp energy crises Many popular texts pamphlets etc have brought ecology into the public eye More has been written on ecology from 1968 to 1972 than in the preceding 100 years Unfortunately Ecology is misunderstood Frank Fraser Darling animal ecologist The trouble k0 with ecology everybody will get sick and tired of the word before they find out what it means Some see it as a fad of the young earth days etc with problems grossly exaggerated but ecology is as old as mankind Worse some see it as anti progress unpatriotic somehow communistic or socialistic Remember what Choo Choo Charlie Wilson said What s good for GM is good for America Paul B Sears Bioscience 14 711 Ecology a subversive science Jeremiads and spreaders of bad news to some commentators Old ecological problems have been long recognized just ignored Some even say that pointy headed egghead professors are causing problems However nearly all the serious problems of mankind are essentially ecological overpopulation famines poor food production malnutrition soil erosion pollution of air water amp land with toxic wastes chemicals insecticides metals like Hg amp Pb fungicides herbicides heavy radioactive isotopes environmental deterioration deforestation global warming ozone depletion urban sprawl social stress diseases real diseases like Malaria amp Yellow Fever and other communicable diseases are made worst by overpopulation the list goes on and onShow population figure For a long time ecologists have tried to get attention of the public see George Perkins Marsh s Man amp Nature 1864 In the 1930 s FE Clements Paul Sears amp W Vogt Road to Survival F Osborn s Our Plundered Planet 1948 1948 A Leopold s Sand Country Almanac Rachel Carlson s Silent Spring 1962 10 Changing attitudes gives hope Started with photos of Earth Beautiful Blue Green World with surfs of white clouds in contrast with dead Barren Moon and later Mars appears to be equally barren despite the discovery of microbial fossils in meteorites from Mars Truly Earth is our spaceship nowhere else to go Space is vast amp hostile the nearest stars light years away It s sobering to realize our Earth spaceship is old 4 5 billion years old oldest rock with life dates 39 billion years it s incredibly old Evidence is strong that Earth behaves as Gaia though it is itself alive Lovelock s the Goddess of the Earth in hypothesis Gaea Greek mythology The evidence is that life has been maintaining conditions for life for billions of years on our planet To fully grasp such a sweep of time set in 7 days of Creation of history of life on the planet beginning about 5 Billion years ago Sunday to Tuesday Basic Construction 39 Bya Friday First large Fossils Cambrian Period Noon Tuesday Life 06 bya 600 mya Saturday 500 PM oil is being formed 700 AM morning cockroaches appear 400 PM Dinosaurs appear become dominant 900 PM Dinosaurs disappear 1000 PM Big Mammals appear 3 minutes early hominoids appear 11 seconds Neanderthal man appears 1 12 second Agriculture begins 14 140 Industrial Revolution begins Christian Era begins 1500 An economist teaches that growth as a natural and good and sees nothing wrong with driving perhaps 15000 species into extinction each year 15 World is not well there are too many people and we are fast exploiting the world Consider that the formula for doubling time is about 70 divided by the of growth Population growth of 2 means that a population will double in 35 years Our use of earth s resources are rapidly increasing For example electrical use is increasing at 7 doubling in 10 years 16 Remember Jacques Costeau s French riddle of the pond and the water lily on which day is pond half covered if a lily pad doubles in a day That leaves us very little lead time to solve real problems while we are often engrossed in trivia w 11 Behavioral Ecology Ethology Introduction Strangely there is a tendency of ecology textbooks to on one hand leave out animal behavior ethology and on the other hand in the same book refer to behavior repeatedly in many contexts In your Class Notes Package pp 399 417 is a chapter on behavioral ecology from an earlier edition of Smith It would seem in your text that you are expected to know about it yet ethology a highly specialized course Perhaps West Virginia has such a course thus the elimination of this chapter Here are some textbooks on Behavioral Ecology or Ethology Since behavior deals with what an organisms does that is reacts responds to stimuli and that the stimuli constitute part of the environment en clearly behavior by the definition of ecology falls squarely into the realm of ecology Clearly then behavior should be considered part of the ecotope the ecology of a species Part of this ambivalence is the unusual history of behavior studies reflecting the importance of behavior to our own species 1 N 2 as Philosophy gt Psychology a Psychology seeks to understand ultimately behavior b Psychologists may use animals but as tools ultimately to understand human behavior c Psychologists get PhD s and psychology overlaps with anthropology and sociology as human sciences d Many psychologists go into clinical work and work as psychotherapists to help the mentally sick human Medicine gt Psychiatr aAbnormal behavior Mental diseases are treated as parallel to conventional physical illness b Psychiatrists get MDs and often become pill pushers vs psychotherapy for mental disease c Research psychologists may use animals again as tools to understand sick human behavior Physiology gt Neurobiology aPhysiology itself derives from medicine Overlaps with medicine in ill human behavior with respect to neurobiology b Relates to comparative physiology neurobiology Natural History gt Zoology gt Ecology gt Ethology Ethology is the comparative study of animal behavior for its own sake which leads to the significance of behavior in ecology and this leads animal directly to evolutionary ecological meaning of behavior U I Sociobiology This is the study of social groupings in an evolutionaryecological context Human behavior interpreted in these terms becomes controversial 6 Behavior What an organism does is thus a crossroads between Physiology Psychiatry and so Ecology Evolution Psychology Sociology and Anthropology very important to H sapiens our species C The fundamental unit of neurobiology is the physiological reflex arc based upon neurons that convey nerve impulses l Stimulus This is any change in the environment that elicits ultimately a response in the organism 2 Response seeks to extinguish the stimulus 3 In animals This is a reaction to a stimulus that the Central Nervous System CNS includes a The afferent or sensory neurons that convey information about the stimulus to association neurons of the CNS The association neurons that process the signals and decide on the neural responses to stimuli The efferent or motor neurons that convey the signal to effectors to elicit the response This overhead diagrams the animal reflex arc 4 Receptors are organs that respond to stimuli and create to CNS a b nerve impulse signals via the afferent nerves Organisms differ in what they perceive Consider the animals only three phyla have eyes the other phyla have merely a light sensitivity at most The arthropod s compound eye is very different from a mollusk or the vertebrates camera eye Other animals may perceive what we cannot as ultraviolet light in insects infrared receptors in pit vipers magnetic directions as in many birds or electrical fields as in some such fis 5 Effectors make responses to stimuli aGrowth and osmotic responses as in plants b Flagella cilia and amoeboid motion as in protozoans c In animals via the CNS efferent nerves muscles are stimulated for locomotion and masticulation However sponges while animals cannot move their bodies and can only use flagella to make currents for feeding 6 dPogonoporans and tapeworms have no intestines so must absorb food from the medium In animals a response may be chemical production by glands exocrine and endocrine Semiochemicals bear information Pheromones function Within a species allelochemics function between species for chemical communication Plants make poisons nectar attractants and allelopathic chemicals the inhibit growth of other plants in competition for space In association neurons a key distinction a b Innate behavior is hardwired non learned behavior already in the neurons Learned behavior is based on neurons having the capacity to learn from experience and remember that is to have memory D Ethological studies 1 One must know your species well Know its sensory and effector capabilities Know its biological rhythms and life cycle 2 3 4 Natural field studies are best as strange conditions in the lab may produce erroneous results especially if the animals are insufficiently acclimated Be careful of teleology and anthropomorphisms in interpreting animal behavior Think about proximate or physiological causes and ultimate or evolutionary causes for a behavior how does it enhance the survival and reproduction of the animal Take care don t attribute human thoughts to animals E Species Specificity Behavior is ultimately the product of evolution of natural selection Whole of description and categorization of animal s behavior is an ethogram Pg 16 in Class Notes gives a list of behaviors that may be in an ethogram Every species has a specific behavior good taxonomy is a must Conflicts and errors are often due to species misidentifications Behavior to varying extents is both learned and innate The capability for both is coded in the l 2 3 4 5 genes Hardwired vs software is a good analogy Innate behavior is stereotyped programmed and directly subject to natural selection An innate complex program or set of behavior is a Fixed Action Pattern Instinct is often used but be careful as the word instinct is tainted especially among American psychologists as excusing one s bad human behavior as being inherited thus not responsible 7 Learned behavior is modified by experience and is based on memory the genes the capacity for which derives from and so is indirectly selected for Generalized types of innate behavior 1 Tropisms a b O U Jacques Loeb 1890 These are growth hormonal and osmotic responses in direct relation to environmental stimuli He thought animals responded this way led by the environment and he used the protozoan Paramecium to demonstrate this Now the idea of tropisms is largely restricted to plant responses positive or negative geotropism positive or negative phototropism etc Taxis Taxes Herbert Spencer Jennings work He found instead that animals have responses more resembled trial and error reflexes and the total orientation was based on simple reflexes as follows A taxis plural taxes is a turning response Paramecium in avoiding light shows a fixed response on meeting an obstacle It backs up into the light direction turns about 30 degrees and moves ahead and repeats as necessary to clear the obstacle A kinesis plural kineses is a non directed movement response to a stimulus until the stimulus is extinguished Taxes and kineses work together Think of the movements of pill bugs in the laboratory to avoid light and dryness Reflexes Classically these are innate responses that are hard wired into the CNS That is quick responses through programmed motor and association neurons Again show a reflex arc in vertebrate CNS There are many simple innate reflex arcs in humans as the knee jerk startle response hair rising the eyebrow lift the suckle response of babies The above taxes and kineses are simple reflexes for turning and moving with reference to stimuli Often complex innate behavior is a chain of reflexes as in the butterfly mating behavior on pg 401 in class notes some cases there is in place a hardwired set movements If the dorsal root sensory nerves is cut swimming walking turning continue so it is not a reflex chain for many basic movements but a coordinated whole motor response 1906 reexamined Loeb s eg H 3 of e Reflexes can affect hormone release as in the anole chameleon and its color changes f Freezing and playing dead are reflexes of no movement so as to fool a potential predator g Salivation sweating breathing etc are reflexes to internal stimuli as well as to external stimuli G Simple learned behavior based on memory 1 Habituation aThis is learning not to respond bExample of Stentor and carmine by H S Jennings 2 Classical conditioned response aAssociate new stimulus for the original stimulus bPavlov and dog s salivation for food dog learned to associate bell a new stimulus with food c Fish and food tap on glass needs no great intelligence to learn new stimuli 3 Operant conditioned Response aAnimal learns a new response by rewarding the new response Reward becomes a stimulus via memory of behavior b Skinner at Yale was so effective in using this technique that he could teach Pigeons to play ping pong for food monkeys to run amazing routines for food even curiosity Trial and error or and reward gt learning gt self conditioning success gt reward cSome behaviors are easily learned since animal is already programmed to learn them dFor example with earthworms better to use vertical mazes instead of the conventional horizontal mazes Flatworms that ate ground up trained flatworms learned faster suggesting early on that there s a chemical basis to memory fNote We do not yet understand memory memory permits behavior modification that is learning 0 39D H Ethology and complex behavior 1 Three men won the Nobel Prize in MedicinePhysiology for their work in Ethology I will discuss each scientist in the context of his work 2 Nikko Tinbergen a Dane who moved to England worked on releasers sign stimuli and internal motivating factors in fixed action patterns 3 Konrad Lorenz worked importance of imprinting in learned behavior 4 Karl von Frisch worked on the language of the bees I Fixed Action Patterns FAP Instinct Tinbergen lThis is a complex stereotypic innate set or chain of responses to a stimulus 2 Instinct Complex FAP Bout but which may include learned aspects Avoid using the word instinct in psychology because of the taint of excusing bad human behavior by calling it an instinct 3 To express a FAP the animal must have Internal Motivating Factors present to react to a stimulus a Maturation hormones all systems must ready to be expressed when stimulation occurs b Appetitive behavior expresses biological drives 3 Sign stimuli are external mechanisms that serve to initiate an innate fixed action pattern in the CNS 4 A Releaser is part of the anatomy39that can serve as a Sign stimulus Examples of work on FAP s l Tinbergen showed that the spot on the side of a Herring Gull bill is a Releaser that elicits begging for food in a baby gull At the same time the open bill of the chick with its yellow lining is a releaser that elicits feeding behavior by the adults Note again the releaser serves as a sign stimulus 2 Tinbergen also showed in stickleback fish in which males are territorial and the females lay eggs in his nest that the red belly of a male serves as a releaser for aggressive territorial behavior but as a fish reaches the limit of his territory and into the territory of another male dominance reverses For the above work and others he shared in the Nobel Prize 3 In flickers the black mustache of male has double releaser function aFirst it releases territorial defense in a male and second courtship behavior in females b Paint on or over the mustache and it changes the responses of the observer 4 Oystercatcher This bird shows superreleaser behavior in which the bird will reject its own egg for an extra large artificial egg She normally would choose the larger of two eggs she laid to incubate 5 It releases territorial behavior for a male bird to see the image of itself seemingly of another male Thus it s mean to put a mirror out in a forest 6 Birds are especially popular in behavioral studies because of the visualauditory stimuli are perceived by the investigator as well aAlso birds show many interesting FAP s combined with much learned behavior bThis reliance on FAP contrasts with mammals which have generally a greater percentage of learned behavior which leads to us 7 Insects often have interesting intricate FAP s a Mosquitoes will respond and attempt copulatory behavior to a tuning fork of right frequency b Moths are famous because in many species the males will travel miles following the pheromone of a female and will even attempt to copulate wit paper scented with female pheromone c You recall the butterfly mating behavior with its chain of reflexes Releasers clearly then can act for communication 1 Already seen communications about care giving and care receiving in gulls 2 Territorial displays and songs ensure spacing for raising offspring 3 Distress displays and calls bring attention to danger and predators a Calls of birds crows blue jays are especially effective and can imprint on others danger and fear of even innocuous objects as a milk bottle b Perhaps there are innate responses in birds to outlines of owls hawks snakes and cats but these may be imprinted as well c Flash coloration of many ungulates like white tail deer 4 Deictic pay attention for communication a Identification where he is b Response and excitement level c Finding food shelter d Temporal information when now or future e Many behaviors are not well known such the elaborate songs of dolphins and whales These animals have very large brains and complex social behavior so deserve careful study not merely being destroyed for food f Echo location navigation is found in dolphins bats and gyrinid whirl a jig beetles Von Frisch for which he won the Nobel Prize studied I Language of Bees 1 Consider the conditions for communication in hive It is dark the bees cannot see each other nor see outside Next note that a bee does many things in its life history and does not become a scoutwork bee until late in its life Only females work 2 When a scout bee arrives at the hive he goes inside and announces his presence by the vibration of his winds and that he has a message to communicate If she has found a source of nectar and pollen nearby she undergoes a round or circle dance The bees nearby follow the scout bee for the circle dance and smell her for the identity of the flower and listen to the intensity of the wing vibrations as to the value of the food The attending bees are told that the source is so close that no directions are given If the flower source is a long ways off then careful directions must be given By using colored pans of water von Frisch was able to establish that bees can see color and by moving the pans was able to demonstrate that the bees communicated precise directions As before when the bee enters she announces her presence but now she dances a figure 8 dance on the surface of the comb a The abstract convention that the scout bee makes is that the up position on the comb is the position of the sun Because bees can see polarized light bees can tell sun position without actually seeing the sun b The scout bee dances in a precise angle from the vertical This equals horizontal angle of Sun with reference to the exit from the hive to the location of the flower source Next the scout bee must tell the other bees how far away is the flower source This is done by waggling the abdomen from side to side The slower the waggling the further away is the distance of the food flower d The scout bee vibrates the wing muscles as before it to indicate the excellence of food source e The bees in the hive closely follow the scout bee in the dark to learn these direction and also learn the odor of the flower on scout bee so the can find the flower when they arrive at the source location f When von Frisch was experimenting with moving the colored sugar pans he discovered to his surprise that the bees learned the moving of the pans and the scouts would be waiting for the pans to be moved 0 g Because the sun is moving across the sky the bees use an accurate clock sense to adjust for the changing sun position with reference to the flower and the hive h Even more remarkable if a trained bee is removed from the hive to another location J Learning vs 2 2 as where the flower is not visible but the hive is the bee does not return to the hive to get its bearing but reads sun position and triangulates and flies directly to the flower 2 Human languages based on learned symbolism a It is very much like imprinting our language acquisition at an early a e b Interesting while apes anatomically cannot speak they can be taught sign language and communicate very well Do they have language This has been very contentious c An Italian nobleman locked some children up as he wanted to hear God s language when they spoke The children had no language Instinct Stereotyped behavior of PAP vs flexible modifiable learned behavior we have Which is better a BOTH consequences of natural selection Mammals evolved to exploit learned behavior wit minimum of innate behavior b Most animal species integrate together both learned and instinctive behavior Nest building by a bird is stereotyped But the next building improves on bird s learning of which materials are available and suitable d Emphasis on learning by psychologists because of its human importance Thus psychologists and human physiologists tend to ridicule instinct as a subject to study as it does not have reference to Homo sapiens Learning is involved in the perfection of stereotyped behavior We do not learn to walk per se it s wired in however maturation develops the necessary coordination aspects of balancing where to put feet danger of falling etc are learned Behavior must mature must have a developmental background Practice makes perfect Much learning is programmed capacity to learn We learn to talk so readily because our brain is pre wired to learn to talk even without words as in sign language among the deaf Rather like imprinting it must occur at a particular age to be effective Recall our human problem of learning a new language late in life compared to ease of learning in early life Thorpe studied the song of the male Chaffinch a European Bird a When the males are raised in isolation It sang no songs only calls and cannot learn it later 0 b If on the other hand the chaffinch hears its song at 6 months it sings its song Is the song imprinted However it will not sing the songs of other birds Moreover if the chaffinch song is played backwards the bird sings the song forward not backward showing the basic song is already innate 5 Song Sparrow amp Swamp Sparrow are closely related birds with very different songs They similarly will not sing unless they can hear they songs a If the songs are alternately spliced together each species sings only their own song b More careful study shows that the male birds are actually listening to successful males and are learn local dialects of own song Imprinting the dialects so as to sin beautiful song to attract a lady love who can be very choosy Humans seem similar Remember the Shibboleth password in the bible which Samarians could not say and spies could be caught and executed Our diversity of languages works to identify membership in a tribe 6 GP Baerends in the Netherlands worked with Digger Wasps Ammoghila camgestrisz The wasp provisions its nest cells underground with a particular species of caterpillar The wasp has several nests to provision a The wasp learns the position of stones amp twigs around the entrance Baerends moved the stones and twigs and the wasp couldn t find the entrance despite it being plain sight b Also the wasp examines her cells to see if more food is needed for her babies When Baerends stuffed caterpillars into the nest the wasp continues to try to put food into her nest despite it being full of caterpillars 7 Gulls learn tiny differences among chicks in communal nesting areas but cannot distinguish enormously different eggs Eggs don t run around and get lost So the gull is not programmed to learn eggs 0 O K Social Behavior 1 Sociobiology the biological basis of social behavior became a controversial subject through publication by EO Wilson of an excellent book of this title I recommend it and his other books He is an excellent specialist on ant taxonomy as well 2 Also I recommend reading The Selfish Gene by Richard Dawson who gives an excellent genetic perspective on ethology and sociobiology Incidentally I should 3 4 also recommend Dawson s excellent new book The Ancestor s Tale the follows as a pilgrimage the 4 billion year old course of evolution from now back to the ancestral microbes Social interaction is based on communication by signals a Of course not all behavior is social spent in individual needs b Social behavior must be related to its evolutionary advantage and to energy budget Shows must eat up to their own weight a day in food and have high energetic needs Yet shrews make scent trail markers to promote spacing of population for food available d Spatial ordering keeping in touch at a distance Territoriality displays promote spatial organization and reduces conflict Social Structure is a characteristic of a species and should be studied with reference to the advantage of the social structure in the survival and reproduction of the social group so is important in population ecology and population control as we will see later a Size and density of social unit b Territoriality simple structure when pairs compete for territories for breeding c Breeding territories differ with monogamous and polygamous usually polygynous harems d Group or social territories are found in some birds and many primates Breeding structure can be temporary to a breeding season or be more permanent from year to year a Pair bonding can temporary or consort monogamous that is serial monogamy during a breeding season as is found among pintails mallards but longer term pair bonding as among geese swans and cranes and gibbons However it should be emphasized that there is a fair amount of cheating which is can be interpreting as the female maximizing her fitness by using several males for source of sperm for offspring While in polygamy polygynous harems are the rule polyandry several males to a female found in some schooling fish few birds such as the tinamous and a few Human Cultures where it is advantageous to have several males helping the female especially when the male cares for the offspring or incubates a clutch of eggs c Few social species are promiscuous and show no or only transient pair bonding as in bonobos and chimpanzees in which groups there is much is O U is extensive sharing of the responsibility of caring for the young animals Lek behavior is where many males display together for attracting females Some ground birds as the prairie chickens sharp tailed and sage grouse form leks but leks are common in many insects especially flies in which the males forms swarms that display to attract the females which enhances a male s chances of finding a female 12 Physiological Ecology or Environmental Physiology I Introduction 1 As stressed in Systematics and Ecology all organisms are divided into species different species of plants animals and microbes 2 Species you recall form populations in a community defined by continuity of reproduction of a common genetic message the DNA that codes for the anatomy and physiology of each organism as an individual a population and a species 3 A species is not everywhere but it occurs in a location characteristic for the species Habitat which is therefore the physical environment of a species to which it is adapted by natural selection 4 Contrast the concept of the biotoge place where an ecosystem occurs Recall biotopes are grouped especially in the terrestrial environments into ecoregions and these into terrestrial freshwater and marine biochores 5 What a species does in its ecosystem is its ecological niche that is its role in the ecosystem The habitat and the ecological niche together form the ecotope that is the entire species ecology 6 The adaptations to the habitat comprise the physiological ecology of a species or the environmental physiology and represent an intersection with physiology Use much the same methodology and experimental design as physiology 7 It s important to recall that DNA the code of instructions changes by selection for the genes responsible In Natural Selection those individuals in a population that survive to reproduce were genetically able to handle the environmental situation that they were in and their genes are therefore with much shuffling of the genes by sexual reproduction transmitted to the next generation These will go through a similar bout of selection through survival and reproduction so generation by generation natural selection leads to continually adapting to the environment including its changes In Artificial Selection we ourselves choose the survivors II that reproduce their genes thus all the breeds of domestic animals and strains of plants Because each biochore differs fundamentally in its physical regulators most physical factors will be discussed when we discuss the general biotopes of the biochores Here I will stress some general concepts and discuss in more detail two factors important in all biochores temperature and periodicities which are often linked together by energy General Concepts A Law of Minimum 1 Justus von Liebig the founder of organic chemistry in response to a request by the French government about wine production in 1840 realized that an agricultural crop is dependent upon the nutrients available He therefore founded the science of Agricultural Chemistry too 2 He demonstrated that if one of the various nutrients even a trace one was absent the plant suffers and can die 3 If a nutrient is present at inadequate amounts then growth is similarly minimal or limited by the nutrient 4 He viewed the nutrient requirements as a chain of requirements and whichever one is in least quantity compared to needs then forms the weakest link Add more of another nutrient such as N03 when P04 is low would not help the lack of P04 5Thus the minimum limiting factor the quotLaw of the Minimumquot Law of Limiting Factors and Law of Tolerance 1 FE Blackman 1905 a plant physiologist noted that there can be too much as well too little and called both extremes limiting factors thus the Law of Limiting Factors 2 VE Shelford 1913 proposed a more general concept that he called the Law of Tolerance Fig 51 in Smiths 3 He applied it to food temperature water humidity etc as well as nutrients 4 OX C Shelford noted that there was a definite range of optimum conditions under which the species survives best and which will also determines the ecological and geographical range of the species Tolerance can be defined by the responses to a factor by an organism or population of a species a Survivorshi bGrowth and reproduction c Behavioral choice d Geographical and ecological distribution In a population to measure resistance to a toxic agent as DDT one may use LDW lethal dose for 50 of the population Species vary widely in their tolerances Use the prefixes Steno and Eury Steno means narrow Eury means broad l 2 0 as 01 6 Euryhaline stenohaline Estuarine as compared to either marine or freshwater Eurythermal Stenothermal Compare mosquito fish with tropical fish Euryhygric Stenohygric is moisture adaptations Eurytopic Stenotopic is broad versus narrow environmental adaptation Acclimation versus acclimatization in tolerances Note Smiths are in error a To acclimate means short term adjustments day to day as in the laboratory before an experiment Compare tropical fish and Gambusia mosquito fish again in acclimation ability You can see this as part of organismal homeostasis maintaining the steady state To acclimatize is long term over the year seasonal adjustments Acclimatization often involves extensive physiological changes in tolerances Fig 52 to permit survival in changing environments from say winter to summer in the so called quottemperatequot zone Ecologists are usually most interested in the steno factors because these are Dquot the ones that may limit an organism to a given habitat or its geographical distribution a For example O2 is abundant on land in air so terrestrial ecologists normally ignore it bIn contrast aquatic ecologists always have a BOD bottle or meter ready for oxygen determination 7 Organisms that are broadly tolerant to climatic conditions often have very wide geographical distributions and can occupy a wide habitat range 8 Narrowly adapted organisms may not be so widespread etc but may be very abundant under particular conditions because they are very efficient under those particular conditions Factor Interaction 1 When starving or malnourished an animal s resistance to parasitism and disease may be so lowered by the poor diet that it will die not by starvation itself but by parasitism or disease or being weakened by predation rarely does an animal actually directly starve to death in nature 2 Factors sometimes may have supplementary effects as in some mollusks if calcium is lacking then strontium can be used to make up the deficiency as strontium is similar chemically to calcium 3 Some estuarine animals can live in lower salinities at higher temperatures In Texas oysters can live in some estuaries in the hot summer but die back in the cool winter 4 Ecologists have plenty to learn not only about the existing adaptations but the effects of man s pollution as of oil chemicals and sewage as limiting factors 5 Take for example what happened to the oyster fisheries in Great South Bay NY Home of the famous Blue Point Oysters when an off season business was adopted a Duck farms were established that produced excess nitrogen nutrients but nothing evidentially harmful to the oysters as shown by laboratory tests b However the eutrophication favored a new phytoplankter species that could use NH4 and urea It was really new it had to be described as a new species c But oysters didn t seem harmed or poisoned by the phytoplankter either in laboratory tests 6 Only later after the oyster population had crashed was it discovered that the oysters couldn t digest this new phytoplankter and had starved to death 7We need to be cautious about the stew of chemicals we are producing and worrying only about ourselves Some seemingly harmless have proven to be are dangerous in other animals such as in the hormone mimics that cause intersexes and aberrant behavior in fish and amphibians or herbicides that kill toads at extremely low concentrations It has been repeatedly observed that amphibians are taking a beating the world over and this may be the consequence of our activities E Geographical variation in adaptations 1 For example little blue stem grass Schizachyrium scoparium a species found from Canada to Mexico when transplanted from the Dakotas to Texas did very poorly in Texas in the summer and never flowered as the days were not long enough Conversely a Texas population transplanted to the Dakotas died in the winter and bloomed at the wrong time Same species different physiology 2 Such genetically adapted variations of same species are called ecotypes and are not described as taxa by taxonomists Realize that a continuum of plants stretches from Canada to Mexico and genes may flow from plant to plant so the populations are not reproductively isolated 3 Don t confuse these with ecophenotypes which are variants that reflect different physiological or developmental reactions to environmental conditions not genetic variability nor with physiological acclimatization such as development of winter hardiness in plants and animals in the autumn These are also not named taxonomically as they do not breed true However if a species show morphological difference related to geography a subspecies designation may be made especially in zoology 5 Or in botany if a population in a different environment differs morphologically and the difference is genetic population may be designated a variety as in the case of Schizachyrium scoparium var littoralis that grows on the coastal dunes of Texas only short distance from Schizachyrium scoparium var scoparium on the Texas prairie as F Age Variation 1 During the life cycle of an organism one of the stages frequently the early stages is less tolerant than older For example the lobster is quite tolerant of cold water all through the stages except the early post embryonic stage of the larvae which demands an average temperature of 11 C 2 Blue crab males must leave estuaries out to fully saline water for larvae 3 In general the old and the young are the most vulnerable to harsh environments G Length of Exposure is Important 1 For example the blue mussel in the winter lives south of Cape Hattarus but in the summer prolonged exposure to temperatures above 27 C the population cannot survive and the blue mussel39s range retreats north III 2 In the laboratory this means measuring LDW should be done in time intervals of exposure 3 Moreover even if they survive in the lab they might be sterilized thus genetically dead so further testing would be needed in raising the organism to discover this Temperature General 1 Temperature is very important and it affects other physical conditions such as relative humidity rainfall and solubility of gases and solids in water In poikilotherms body temperatures vary with the environment Homoiotherms maintain body temperature independent of the environment Homoio is closer to the original Greek than homeo and homo 2 Recall Chemical law of Qm 2 Van Hoff s law Every 10 Celsius change in temperature results in doubling or halving of a chemical reaction applies to life39s metabolism as well with enzymatic restrictions a Enzymes are nearly all protein catalysts b If too hot denaturalization may occur with an enzyme losing catalytic power analogous with cooked egg white gel Catalysis stops c In general the more the catalysis by enzymes at low temperatures more sensitive are the enzymes to denaturalization 3 Organisms adapt for maximum catalysis and efficiency in their habitats 4 Body temperature is a function of heat gain and heat loss thermal energy exchange and mass of an organism as well as metabolic heat production 5 Limits for life reflect liquid water exception proves the rule Cryptobiosis bacteria lichens mosses algae protozoans tradigrades rotifers nematodes few vascular plants as the resurrection fern and few insects Midges Once dry may be oven dried B 1 don39t burn microwaved or put in liquid air Survival happened because no free Ego was present Return to normal moisture life activities resume amazing phenomenon allowing survival Tolerance Limits of Poikilotherms Resistance to absolute temperatures Yellowstone National Park Geyser is a natural field laboratory a Thermophiles live gt40 C Bacteria gt955 C Blue green algae 73 75 C Fungi Algae 56 60 C Protozoa animals vascular plants 42 52 C The thermophilic bacteria have enzymes without tertiary structure no great catalysis required as it is hot but bacteria may die at low temperatures Called extremophiles many Archaeobacteria in deep sea vent biota live in superheated water under great pressure Others live in cracks in the deep rocks of the Earth this may be a separate biochore in the earth s hot rocks and raises questions about the origin of life Mesophiles die at 40 C Denaturization of enzymes is critical limit Psychrophiles die at 25 30 C or less Deep sea at 25 C 275 F animals may die at 5 C 41 F Enzymes of psychrophiles are ver sensitive to heat High pressure also reduces metabolic rates Van Hoff s law functions in organisms a If Qm 2 this means the doubling at a rate of chemical reactions every 10 C increase metabolism similarly will double to the lethal point It is characteristic of most poikilotherms to live in a range of enzyme action If too cold a poikilothermous organism becomes torpid or dormant Often cold adapted poikilotherms can t survive warmer conditions b C b C d Some poikilothermous animals as horned toad lizards have a stable metabolic rate over quite a temperature range as van Hoff s law does not operate over the whole temperature range only sections each section has a different enzyme functioning at its optimum temperature sum is large range of function e Cool adapted species may become dormant at a higher temperature to avoid excess energy use and in water to avoid low oxygen levels f Wind chill homoiotherms are affected but not poikilotherms consequence of evaporation of water and cooling on heat retention 3 Environmental variations in temperature a Tropical poikilotherms usually can stand but little fluctuation Ecuador has 05 C annual variation night is the winter of the tropics b In contrast in quottemperatequot zones there are rapid changes as for example when a Texas norther comes through it may drop from 35 C to 0 C or lower in hours tidal flat and rocks may fall from 38 C to 10 C when tide comes in deserts often vary 40 C between day and night c Over the year in North Dakota from 43 C in winter to 49 C in summer that is 50 F to 120 F dOrganisms must acclimatize twice for winter and for summer to handle such seasonal variation C Temperature Regulation 1 Homoiotherms regulate temperature within narrow limits and are endotherms that use heat of metabolism to maintain body temperature but also cool the organism for homeostasis a Advantage of homoiothermy constant physiology It allows narrow temperature range for enzyme activities at maximum catalysis at an optimum temperature b Maintenance in air medium easier because H20 has too high a specific heat and conduct heat hard to regulate body temperature very few true aquatic organisms are homoiotherms Those that are have insulation derived from adaptations in the terrestrial environment c Homoiothermy made possible by insulating layers heat feathers blubber for heat loss control and controlling blood flow to skin and by more thermogenesis by muscles and by brown fat dAlso important is cooling by panting perspiring seeking shade eSome endotherms are not homoiotherms such as the skunk cabbage flower that pushes through the ice and snow in spring in swamps in eastern North America and the snow anemone that blooms in the alps melting its way through the snow in alpine areas 2 Ectothermy Heat from without the animals from the sun aTerrestrial poikilotherms as many reptiles and insects use ectothermy to control body temperature by regulating exposure to sun going to shade to cool bSuch animals are quotwarm or hot bloodedquot during the day Thus warm blooded is a misnomer for homoiotherms as compared to such poikilotherms A lizard may be hotter than you in the day in summer c Basking in sun to raise temperature is an advantage for aquatic reptiles as when they return to water to hunt fish their temperature is higher 3 Heterothermy mixture of strategies a Insects when flying generate a lot of heat so are endotherms but when resting are poikilotherms To regulate flight temperature must pump blood from thorax to abdomen to cool vice versa to heat Moths have a heavy layer of scales that enhances endothermy for flying at night and also promotes raising body temperature to flight temperature by shivering c Daily torpor seen in some birds hummingbirds and poorwill and in small insectivores and rodents bats by day to conserve energy near ambient temperature during torpor 4 True Hibernation heterotherms many small mammals rodents insectivores bats some marsupials Oquot a In ordinary dormancy temperature drops then physiological responses slow b Some vertebrates in deserts adapt torpor to aestivation oversummering c In true hibernation metabolism rates drop then heart rate and breathing then body temperature drops Some rely on body fat others awaken periodically and feed d If body temperature drops below 4 C the metabolism increases to maintain 4 C thus is a homoiotherm e Bears and skunks deep in sleep have high metabolism hibernation through lowered activity Urea controlled and resorbed Bears give birth during hibernation and suckle cubs D Critical temperatures 1 Critical temperature in homoiotherms a Penalty of high energy use for temperature regulation is that it squanders energy Animal needs food to maintain body temperature b Resistance to cold and heat stress Critical temperature is when it exceeds the ability to thermoregulate c Cold critical temperature marked by heightened metabolic rates big energy loss 2 d H1 Varies with insulation body size and shape bulky in cold spindling in hot to enhance heat retention or heat loss Surface area volume Bergmann s rule bulky organisms have smaller surface area to volume lesser loss of heat Subspecies in colder climates have larger body sizes hotter climates subspecies have smaller body sizes Note a subspecies is a taxonomically distinct geographical population of a species Bergmann s rule is much used in vertebrate taxonomy Allen s rule short extremities reduce surface area thus reduce heat loss Subspecies in hotter climates have longer extremities Tropical animals have high lower critical temperatures like us Contrast this with the arctic fox really a dog which has 40 F lOow critical temperature Very small mammals and birds be cannot adequately insulated because of unfavorable surface area volume ratio Birds better at controlling temperature than mammals Feathers are excellent insulators For poikilotherms critical temperature is the inability to move and survive to avoid freezing and cooking Gloger s rule subspecies are darker in cooler humid areas and lighter in hotter drier areas Partly heat absorption and reflection partly protective coloration against background coloration This is a different subspecies rule 3Adaptations to extreme conditions are l 2 critical in poikilotherms Animals regularly avoid extremes by moving In hot deserts animals may be nocturnal to avoid heat 3 In extreme cold a snow blanket may covers ground and insulates small animals 4 It may be too hot or too cold for active state metabolism may lose too much heat or gain too much a Go into a state of dormancy or quiescence b Cold dormant hibernation c Hot dormant aestivation also against dryness d Conditions impose on low metabolic rate or inactive states poikilothermous animals and plants cold stupor e Some animals even if hydrated can be frozen and survive because extracellular Hg freezes dehydrates cells Ego moves by osmosis f More usually organism is supercooled by antifreeze depression Glycerol water 0 colloidal states not understood how conifers 60 C needles survive freezing g Plants must sit and take it remarkable resistance of arctic and alpine plants Frozen brittle as glass in the morning fine and photosynthesizing by noon 5 Diapause is a special dormancy found in many terrestrial invertebrates insects snails and mites It serves as a life cycle regulator a Diapause lasts for a definite period of time and persists regardless of external conditions b Generally a triggering stimulus maybe cold heat or dryness directly but more usually a photoperiodic stimulus initiates diapause IV Periodicity C 1 Diapause may affect just reproductive metabolism no stupor but no reproduction Generally it requires a cold exposure of a certain length of time to break winter diapause similar phenomena found in plants Easily see this in Texas deciduous oaks may drop leaves in fall while weather is still warm In some trees cold dormancy occurs that often requires chilling to break as in apples Plant cold dormancy is much the same as diapause Diapause prevents the organism from becoming inadvertently active in the wrong time of the year Diapause often may extend from late midsummer to next spring or autumn to autumn thus life cycle regulator Southward limits often determined by cold requirements as with apples to break cold dormancy or diapause A Extrinsic Rhythms of nature reflect the basic exogenous physical cycles lDie1 not daily 24 hours day and night based on Earth39s rotation 2 Tidal rhythms 124 hours based on moon s revolutions with respect to the sun and the earth s rotation creating tides and the phases of the moon 3 Lunar rhythms 28 days lunar 305 days sidereal phases of moonlight also most important in the marine environment where it relates to tides 4 Annual rhythms of 365 days Seasonal cycles governed by photoperiodicity B Intrinsic rhythms are internal physiological rhythms reflecting the endogenous biological clocks that are entrained with the extrinsic rhythms Zeitgebers are the external environmental cues that organisms used to reset the biological clocks Will discuss here just diel rhythms other rhythms will be discussed under terrestrial and marine biotopes 1 Few organisms appear to be not rhythmic at all such as many microbes Some microbes do possess diel rhythms and show a biological clock as shown by Dr Susan Golden39s work in our department 2 Some animals such as the Pine Vole Pitzmzs shows a definite endogenous periodicity and searches for food every hour or so but its rhythm is apparently not entrained to any external environmental extrinsic rhythm Some habitats have no known extrinsic cycle to entrain to eg a Cave animals may have no rhythmic environment b Deep sea animals 60 of biosphere there is no light therefore similarly no external rhythms of light C Circadian rhythms Diel rhythms are very common 1 Diurnal Biota a Plant photosynthesis is possible only during day b Day active animals that are vision adapted or warm adapted in their behavior c Most flowers and the insects seeking them 2 Nocturnal Biota include aAnimals such as desert animals avoiding heat bSmall mammals avoiding predators at night cMany carnivores as owls seeking such prey d Night flying insects in dispersal avoiding day active predators as most birds and predatory insects e Bats in pursuit of these insects at night f Night blooming flowers and their pollinating moths and bats 3 Crespuscular organisms are active in the intermediate period between day and night 0 a Vesperal evening dusk active Many are warm crepuscular poikilothermous insects that are warm after the day39s warmth and are seeking to avoid predators in the dusk All the singing insects that keep you awake b Auroral morning dawn active many homoiotherms especially birds big advantage of homoiothermy high body temperature in the cool morning early bird gets the worm Also all the singing birds will wake you in the morning D Discovery of Biological Clocks Endogenous intrinsic or Exogenous extrinsic rhythms l Rhythmic behavior was originally thought to be extrinsic by physiologists and biological clocks were discounted a Indeed some behaviors are extrinsic as shown during the solar eclipses flowers closed birds slept etc This would indicate an exogenous responses b However in many instances animals began responding well in advance of the extrinsic event as best seen in 2 Vertical migrations a In the sea planktonic animals were found to begin to vertically migrate to the surface or swim into deep water long before any extrinsic stimuli were apparent Early workers tried to find minute subtle factor in environment to explain these migration as no one believed biological clocks occurred in quotlowerquot animals b Zooplankters like chaetognaths copepods and mysiid shrimp were found to swim from 20 to 200 meters to surface each night beginning well before the sun set and descending well before sun rise to go to dark depths during the day For a copepod to swim 100 meters is 15000 times its own length twice a day Why c They were migrating to surface to feed on phytoplankters at night and avoiding surface predators during the day by going deep However they must begin early for it is a long swim to avoid being caught by daybreak at the surface and to reach the surface to feed at night How There must be a biological clock as well as perception of depth d Similarly this was found in deep lakes and Chaoborus fly larvae migrate to feed on zooplankton at night and sink in the day to deep dark water of the profundal zone e Deep scattering layer schools of small fish and squid were feeding on descending zooplankton in the dim light f On land vertical migrations also occur with nocturnal organisms like phalangids daddy long legs climbing in trees at night and soil invertebrates rising to the surface at night to feed when the relative humidity is higher and visual predators were inactive 3 Laboratory work showed that many if not most cycles are endogenous and about a day led to the acceptance of Biological Clocks a topic being strongly emphasized by the Biology Department s chair Dr Vincent Cassone Examples a The flying squirrel a nocturnal animal when kept in continuous darkness in the laboratory showed an endogenous rhythm that varies from 22 hours 58 min to 24 hours 21min about a day thus a circadian rhythm Here sunrise is the zeitgeber resetting the clock which must be reset for changes in day length over the seasons Gonyaulax polyhedra a dinoflagellate is well known as a red tide organism that is poisonous to vertebrates It is bioluminescent at night In dim constant light it shows an endogenous 23 27 hour rhythm in bioluminescence that was retained in a U 4 colony over many cell generations for three years Don t need a complex nervous system to have a biological clock On careful study most animals including Man have complex endogenous circadian rhythms sleep hormone levels metabolism salt levels etc are governed by circadian rhythms In vertebrates melatonin is produced at night by pineal gland once the third eye and governs functions of sleep Serotonin is produced in the day and governs day functions Jet lag is created by rapidly crossing time zones as the biological clock was set for the original location Need to re set the clock bright light at about intensity of 10 O clock in the morning serves as the zeitgeber for the human clock It also helps to take melatonin when you try to sleep in a strange time zone This means it is best to keep a regular daily cycle to accommodate your biological clock Remember the deep human rhythm is 8 hours of sleep at night Remember that when you try to pull an all nighter your mind functions very poorly when sleep deprived Why reset the biological clock with a zeitgeber First the circadian clock is not very accurate only about a day second days are not the same in length long in the summer short in the winter Thus the clock must be continually reset for the changing day length over year The biological clock thus allows the most efficient use of body functions for both day and night or for times of rest and activity as in the flying squirrel A Introduction 1 B Nomenclature l 2 Systematics amp Ecology See pgs 370 398 in lecture package Systematics Study of biological diversity and phylogeny includes taxonomy molecular measurements of evolution and degree of relationships etc Taxonomy Practical systematics This is essential to biological sciences Includes species discriminations and descriptions of taxa singular taxon placement of species in genera making keys for identification and provides codes for rules of naming taxa nomenclature that are specific for Botany Zoology Microbiology and Virology A taxon is any taxonomic entity which is placed into a category from species to Kingdom The naming of taxa in categories Linnaeus invented Binomial Nomenclature Each species singular and plural has first a genus plural Genera name which is a noun and second a specific name or epithet which is an adjective The scientific name must be italicized or underlined The author of the specific name is often given as in the examples below to serve as a bibliographic reference Homo sapiens Linnaeus 1758 is of course us Canis lupus L The abbreviation L stands for Linnaeus C latrans Say The coyote The genus name is often abbreviated when understood Lupinus texensis Hooker Bluebonnet of central Texas L subcarnosus Hooker The bluebonnet of eastern Texas Blissus insularis Barber The chinch bug in your lawn in SE USA B sweeti Leonard A chinch bug that I discovered in Texas on wild grasses and so is named after me Mimus polyglottis L The mockingbird The scientific name is descriptive of the bird s mimicking the songs of many other birds The parenthesis as in L around the author name indicates that the species has been moved to a different genus from the one the original author had described the species in Botanists often give also the name of the author who moved it This practice of citing the describer is to find literature on a species which may be listed under several different genera For example I will change the genus of New World Blissus to Americoblissus so the authors Barber and Leonard will be in parentheses In big genera subgenera may be distinguished In zoology the subgenus follows the generic name and is put in parenthesis Botany uses more subdivisions so they must indicate what the subdivision is by an abbreviation Higher taxa singular Taxon The species are grouped into Genera into Tribes into Subfamilies into Families into 1 11 O Orders into Classes into Phyla singular Phylum Divisions in Botany and into Kingdoms The higher taxa may be subdivided as a family into subfamilies A family can be raised to a superfamily making the subfamilies families Taxonomists make a strong effort to make this hierarchy reflect phylogeny as much as is possible Subspecific Taxa Subspecies in Zoology are defined as a geographical or allopatric set of populations that are taxonomically distinguishable from other such populations of a species Note subspecies are NOT isolated reproductively from other subspecies Examples in class of maps of subspecies distributions botanists use this definition but some do not Zoological nomenclature uses a trinomen that is three names Genus species subspecies Author The author given is for the subspecies Zoologists use no other subspecific names and only geographical populations are recognized One subspecies must bear the same name as the species which represents its type locality See Figure of rat snakes distributions on pg 376a in class notes While Botany often uses subspecies much as in zoology botanists must indicate the taxon as a ssp because botany has other subspecific categories as follows Varieties varietas Latin var to distinguish the subspecific taxon from ssp Varieties are usually ecological populations that are taxonomically distinguishable reflecting that plants are sessile and are often be adapted to local climatic and soil conditions as populations whereas most animals are mobile free to move around choosing the best conditions available Forms forma Latin f to distinguish these from ssp and var These are usually individual unusual phenotypes not populations Forms are distinguished in Botany in large part because of the importance of growing plants in the garden A form can be a useful plant to propagate for interest or profit Note the fancy names given to horticultural strains are not forms or varieties or subspecies but are unique names useful in the horticultural trade to distinguish genetic strains useful in the trade Note that none these subspecific taxa should be ecophenotypes that is they should n2 be plastic responses but populations that should breed true based on genetic differences Type concept Each species and subspecific name must have a type specimen chosen by the author of the taxon to represent the species being described Type specimens are kept in important museums where they are available for study so that any one can look at the specimen and so verify the taxon described by the author A type specimen need not be the best or most representative specimen it just represents the taxon as understood by the author when he described the species Because of the importance of are shown an that is geography in subspecies each species and subspecies has a type locality which is from where the type specimen was collected 12 For higher taxa a species is chosen as the type species of the genus and the genus name stays with that species whatever happens to the genus For the family subfamily and tribe names a type genus similarly fixes the name of a higher taxon The higher taxa names are plural nouns C Species Concepts Defining Species l Morphospecies are distinguished by their anatomical features and theoretically this concept does not consider genetic continuity in the recognition of the species In practice many species are discriminated by taxonomists on the basis of morphology because of the lack of any more information just the specimens a Carolus Linnaeus 1707 1778 the founder of binomial taxonomy characterized species based upon morphology but he understood that species bred true through his work in raising plants in the garden He even wrote about what to do with hybrids between two species that were produced in his garden studies b Obviously extinct forms fossils can only be classified as morphospecies One obvious problem with the morphological species concept is that a species is not uniform as there is usually morphological variation of diverse kinds Especially in the case of subspecies the variation can be so marked that many subspecies were originally described as separate species Later it was discovered that these were not genetically isolated and therefore they were reduced to subspecies A species that is divided into geographical subspecies is often called a polytypic species because each subspecies requires a type specimen and a description A monotypic species such as the osprey has no subspecies A different problem with the morphological species concept is the sibling or cryptic species These are species so similar that they were not recognized to be species until biological differences exposed them For example the mosquito Anopheles maculipennis is a carrier of the terrible disease Malaria which is caused by the protozoan Plasmodium However it was discovered in Italy that some populations of A maculipennis carried malaria and others didn t Next these populations were found to live in different habitats The non malaria carriers were found not to transmit the disease experimentally Further experimental work demonstrated that these different populations did not mate with each other Finally careful study of the genitalia eggs etc showed little consistent differences by which the sibling O Q species could be recognized Some black fly Simuliidae species which are also bloodsuckers and disease transmitters are be distinguished only by their chromosomes This all leads to the next species concept 2 Biological Species Concept Better the sexual species concept as asexual species are biological too a As defined by Ernst Mayr a famous ornithologist at Harvard University species are groups of actually or potentially interbreeding natural populations Mendelian populations that are reproductively isolated from other such groups b This concept emphasizes genetic continuity that is members of a sexual species share a common gene pool that is effectively separated by reproductive isolation from the gene pools of other such species Therefore no genes can move from one species another species that is the species are genetically isolated c This process of speciation is ecologically important because each sexual species is free to un ergo separate selection as a population to adapt to an ecological niche and habitat as genes from any other species are prevented from interfering with this process of adaptation d Individuals formed by sexual reproduction are sometimes called genets indicating their membership in Mendelian populations and showing individual genetic variation rather than variation by clones 3 Obviously the biological species concept cannot be applied to fossils although genetic continuity is assumed especially if the species coexist at the same time in the same area so morphospecies concept must be used for fossils 4 Nor does it apply to asexual species that form clones that are genetically isolated by the lack of sex so these are not Mendelian populations a Their similarity and recognition of asexual species as species stems from their genetic descent and selection to fit in an ecological niche and a habitat in the face of competition with other species Nevertheless such asexual species are often difficult taxonomic problems because each female reproduces an almost identical clone that may differ from other clones c Individuals of such asexual species can be called U rame D Reproductive Isolating Mechanisms 1 Reproductive isolation protects the integrity of the species That is the genes for adaptation for a given ecological niche and habitat and not mixed with genes reflecting adaptation to a different habitat and niche 2 Extrinsic reproductive isolation occurs when gene flow between two populations is prevented by geographical barriers that prevent dispersal between the allopatric populations geographically isolating them 3 Intrinsic isolating mechanisms prevent gene flow between coexisting species a Species populations may be sympatric that is the different species populations are together in the same area or ecosystem It is very likely that these populations have different ecological niches Or the species populations are parapatric that is side by side and therefore most likely to have different habitats and probably similar ecological niches In both cases as Mayr stressed the populations of the species are in the cruising range of individuals of the other species s populations 4 Intrinsic Isolating Mechanisms may be divided into prezygotic before fertilization and postzygotic after fertilization Evolution tends to lead to prezygotic isolation because postzygotic is a waste of reproductive effort and is therefore strongly selected against The isolating mechanism are as summarized U Prezygotic Isolation Ecological isolation Habitat differences keep species separate especially if dispersal is difficult and mating occurs only in a particular habitat Temporal isolation The time of mating keeps the species apart For example our two very similar elms Ulmus alata winged elm blooms in the early spring and U crassifolia blooms in the fall Behavioral isolation This is the most important for animals Males recognize females of its own species and females permit mating only with the correct male Usually females are the more discriminatory males the more promiscuous Understandably the female has the larger genetic and metabolic investment in reproduction The male can afford wasting gametes Mechanical isolation The genitalia of male must fit precisely into the female genitalia if not the female usually rejects the male In flowers the structure of the flower may such as to restrict pollinators to only that species of plant Gametic isolation When sperms or pollen tubes cannot unite with the egg and effect fertilization Many marine invertebrates shed eggs and sperm in the water and sperm must find the correct egg by chemical attraction or pheromones If the egg has the wrong odor the sperms can t find it Similarly sometimes sperms are unable enter into the egg Postzygotic Isolation Hybrid sterility Zygote is formed and develops to the adult but the adult is sterile cannot produce viable sperms or eggs so gene flow is blocked The horse E caballus and donkey E asinus is a famous example The chromosome number of the horse is 64 the donkey 62 the zygote combination of the mule is 63 which can t divide in two Triploid plants similar as in the banana which is why it has no seeds Hybrid inviability The F1 between two species is poorly adapted has poor survival and is unlikely to backcross to either parental species so gene flow is blocked Oaks hybridize considerably but the hybrids do poorly as each oak is adapted to a soil type and the hybrids compete poorly and rarely grow to backcross Hybrid breakdown This is when the backcross F2 to poorly adapted does not survive so effectively no genes enter into either of the parental populations Hybrid unacceptability Hybrids form seem normal but are rejected by the parental populations so no backcrosses occur The many species of the genus Anas the dabbling ducks such as Mallard Brown Teals etc can form fertile hybrids rarely but these are rejected and lay no eggs The same is true of many forced hybrids as between a lion and a tiger E Speciation Fossil record indicates 2 patterns of evolutionary change 1 Speciation by anagenesis ana up genesis origin Evolution of an entire population or lineage may result in speciation through geological time in that the lineage changes so much that at different times the population becomes sufficiently different that species can be recognized A gtB gtC gtD This progression is useful to paleontologists because the presence of a given species helps in establishing the age of a rock and is thus called an index fossil 2 Cladogenesis clados branch or splitting means the splitting of a species into two or more species This is much more common and is the basis of the proliferation of species and the evolution of new ecological niches and habitats A set of descendants of a common ancestor is called a clade Accordingly very taxon should be a clade 3 How species come to be is called speciation It s always difficult to determine the cause of events that happened in the past and historical sciences must find evidence from nature that would supports a theory here find the smoking gun of speciation in action happening today The study of variation in geographical populations gives such important evidence F Allopatric Speciation Model l 2 3 This model which is strongly supported by Ernst Mayr is based on patterns commonly seen by taxonomists a The 5 0 U 0 Q B H environments Allopatric spec1es are usually similar in their ecological niches and show weaker reproductive isolation especially if isolated by geography Sympatric species are nearly always dissimilar in their ecological niches and usually show strong reproductive isolation Parapatric species similarly usually show strong reproductive isolation but are usually similar in their ecological niches while dissimilar in habitats Sometimes it is difficult to tell whether one is dealing with the geographical subspecies of polytypic species or allopatric populations of a species A set of allopatric species resembling a polytypic species is often called a superspecies Frequently populations of distinctly different populations when newly brought together will show a whole range of variation in reproductive isolation from none to weak to strong isolation Often such populations are best called semispecies in recognition that the populations are becoming species It then becomes the taxonomist s best judgment as to whether these populations are evolving into reproductively isolated species or are undergoing introgression and regressing back to be at most subspecies This pattern would indicate speciation in action allopatric model is shown on page 381 Class Notes It begins with geographical isolation and gradually the populations diverge becoming subspecies then semispecies and finally species The fate of the populations on being put in contact depends on the degree of difference in reproductive isolation and in ecological divergence If too similar genetic regression may occur and all distinctions are lost If adapted to different habitats introgression may occur but the morphological distinctness remain as subspecies If introgression is limited selection may promote the ongoing evolution of reproductive isolation between semi species Some sedentary species especially in patchy tend to evolve in local populations and may evolve chromosome differences that promote speciation See pg 384 in Class Notes as shown in morabine grasshoppers in Australia If full species status has been reached with reproductive isolation There are three possible outcomes if the populations come in contact a One species will outcompete the other species driving it into extinction This a most probable course of events especially when small isolated populations such as on islands come in contact with large dominant continental populations as often happens when man introduces organisms on islands thus in part causing the high extinction rates on the islands invaded by man and his associates b The species are ecologically distinctive and can co exist Sometimes the species will show character displacement in the zone of overlap that is the species will be more distinctive in the zone of sympatry c Parapatry may evolve when the species are similar in ecological niche but different in their habitat requirements Thus one species cannot invade the habitat of the other species G Speciation by Polyploidy 1 This is a fairly common method of speciation in plants but infrequent in animals especially animals probably because animals poorly handle chromosome variations Consider how a trisomy just three chromosomes of human chromosome 23 causes Down s syndrome In contrast plants not only tend to handle large chromosome variation but be more vigorous especially in polypoidy 2 There are two types of speciation by polyploidy autopolyploidy and allopolyploidy pg 387 388 Class Notes 3 Autopolyploidy occurs when in meiosis the chromosome number is not reduced to the haploid condition but results in diploid gametes which can combine often in self pollination to form a tetraploid 4N plant a The 2N gametes can only combine with another 2N not the original lN parent because that combination is triploid which cannot make gametes This means the parent 2N and 4N populations are reproductively isolated and are therefore separate sexual species c Because such polyploids often look exactly like each other many botanical taxonomists refuse to recognize them as species preferring the morphospecies concept 4 Allopolyploidy occurs after parents often different species with different chromosome numbers and different chromosomes combine to form a healthy but sterile interspecific hybrid a But when the chromosome number is doubled then each chromosome being doubled can now synapse with its double b Take the example of Spartina alterniflora 2n62 our salt marsh grass and the European salt marsh grass S maritima 2n60 In England these species combined and formed by allopolyploidy S townsendiiL a new U species with chromosome number of 2n124 S townsendii is very vigorous and is now wiping out maritima in England which shows one of the dangers of introducing species into new habitats H Sympatric Speciation Models 1 Ernst Mayr spent much his professional life destroying proposed schemes for sympatric speciation in animals how do you keep males away from accessible females Polyploidy he saw as a mechanism peculiar to plants not animals However there appears to be strong evidence for one mechanism that allows for sympatric speciation the host parasite model 2 In nature there are many examples of host specialization where a parasite is restricted to one host This 39 especially true when the host is large and the parasite small So common is this life style that Peter Price an entomologist considers the majority of animals to be parasitic 3 G L Bush who studies fruit flies Rhagoletisl a genus of the Tephritidae whose species are host specific on many different fruits observed what he believed is a smoking gun demonstration of sympatric speciation in action now a In your class notes on page 386 387 is a goo discussion of his evidence that the Hawthorn maggot host transferred to apple and became the apple maggot The earliest evidence of this was in the New York in 1864 Later it host transferred to cherries in Wisconsin in 1970 In both cases the flies had rapidly evolved in adaptation to the new host by shifting their life cycles to correspond to the fruiting times cherry in early summer hawthorn in mid summer apple in late summer as well as adapting to a new fruit b Bush argues that such host parasite speciation is promoted under the following conditions First The male and females both search for the host plant Second The male and female mate only on or near the host plant and the female lays her eggs on the host once a year Third An accidental host transfer sets up an opportunity for natural selection for specialization to a new host plant Those few flies male and female that survived on the alien host might now go to the new host to mate and lay eggs In the case of the apple and the cherry the growing of these plants in adjacent orchards must have certainly promoted this transfer c In a sense this is similar to microgeographical isolation In natural communities the hosts are scattered and not contiguous and selection would be strong for finding and specializing for a host remembering that the host is also evolving to resist the fly and so on in a continual coevolutionary struggle I Importance of speciation in ecology 1 Whether by allopatric or sympatric speciation each event of speciation makes available a new opportunity of change in ecological niche and habitat through natural selection 2 Island populations often show this vividly because only a small number of species could make it to an islan group which lays open the possibility of an adaptive radiation or divergent evolution of the founding species into many new ecological niches and habitats 3 Smith in your Class Notes pg 395 gives a good example from the Hawaiian Honey Creepers of such an adaptive radiation 4 The same thing happened to the fruit fly much used in Genetics Drosophilidae Better pomace fly as the Drosophila larvae feed on yeasts in over ripe fruit Drosophila has radiated into over a thousand species on the Hawaiian Islands 5 Other examples of adaptive radiations are Darwin s finches and the tortoises of the Galapagos the mammals after the extinction of the dinosaurs the radiation of the marsupials on Australia 6 Sometimes by good luck a species gets into a big new opportunity a new Adaptive Zone and radiates to occupy the zone as happened in the case of the whales J Convergent Evolution 1 Often difference evolutionary lineages may evolve species that although unrelated closely resemble each other through being adapted to similar ecological niches 2 In your Class Notes pg 396 Smith gives examples of the placental flying squirrel and the sugar glider There are also marsupial mice moles shrews and rabbits 3 Even insects and vertebrates can resemble each other as in the case of the hummingbird and the hawk moths in adaptation to a method of flower feeding lO IV Energy Flow into Secondary Productivity AGeneral As with GPP and NPP there is GSP NSP but several levels Trophic levels use summary statements of E ow not of species N because species may be omnivorous 8095 Equal must balance E in E out amp all biomass returns to nutrient pools Very dif cult to do animals hide hard to follow life historiesetc Large animals move migrate long distances between ecosystems Many consumers have extensive symbioses with fungi bacteria algae Much work must be done in laboratory on individuals and populations of a species to work out accurate ows of energy Note not cycles ows B Food Chains Webs amp Trophic levels amp Pyramids 1 Any real chain of consumption by heterotrophs examples 2 E 4 V39 0 00gt Food web Summary of all the food webs in a real community it s very complicated show examples Trophic levels are simpli cations that is summary statements in terms of energy First expressed by Elton as ecological pyramids P 8a a Originally of numbers see the gure of pyramids which works if producers are small as blades of grass in a grassland or better in phytoplanktonthe small unicellular plants in the water b Biomass or standing crop is better but look at marine example where the biomass of the plants is much less than the herbivores because the grazers are eating the phytoplankton as fast as they grow so the standing crop is much smaller than the NPP c Much better is the study by Odum on Silver Springs Florida that shows the energy relationshipthis is always yields a good pyramid but note the microbes in terms of biomass as compared to energy use Originally as above the emphasis is on grazing or biophage food chains and often the microbes are ignored Detrital food chains that is saprophage or saprotrophic food chains are based on microbesfungi and bvacteria eating dead plants These are very important in high plant biomass communities as in marshes and in the terrestrial environment Allochthonous is imported from other ecosystems productivity Autochthonous is withintheecosystem productivity This distinction is important in fresh water where leaves and wood fall in the water C Secondary Productivity Measurement 1 Flow diagram of an animal s secondary productivity a b C d Available E ingested not ingested delayed ingestion Ingested digested feces delayed ingestion amp digestion at same trophic level Digested assimilated GSP not assimilated urineexcretion delayed assimilation goes to same trophic consumption level Assimilated E Gross secondary productivity of the animal in turn Gross Secondary ProductivityRespiration Net Secondary Productivity 2 Respiration a MR basal resting rate of respiration b Active rate for activitiesfood gathering running etc c Heat incrementfor homoiotherms to regulate temperature 3 Secondary productivity NSP a Growt b Reproduction c Secretions and other productions such as hair shed scales etc 4 Population studies must measure rates of growth amd metabolism in all life history stages over the seasons a Integrate life history metabolic rates and growth rates b This is known only for larger common or economic species 4 We can calculate various SP efflciencies based on rates of Availability Ingestion Assimilation Growth a Consider that many animals grow as immatures reproduce as adults birds insects while others as many sh and mammals grow as adults b Some species are iteroparous that is repeatedly reproduce as in trees and large animals while others are semelparous that is reproduce only once and die as in annual plants and insects D Respiration variables 1 Rule of 23 a Everything being the same respiration is proportional to surface area because of membrane transport Surfaces increase by the square b While the biomass that is the standing crop increases by the cube therefore as 0 Mass increases by 3T metabolism increases by 2T d Decrease mass by 24 metabolism decreases by 34 EM e We tend to overemphasize biomass deemphasize small and therefore ignore the imporance of size in metabolism f Therefore realize that in terms of metabolism plankton of a lake z z we1gh1ng gmm tonsm of trees and vertebrates 1n a s1m11ar sized area k A special point about the sea High pressure at great depths creates lower metabolic rates in deep sea organisms 2 Homoiothermy amp Poikilothermy a BMR proportional to 70 W34 An heat increment required to maintain resting BMR rate for homoiotherms small birds and mammals must metabolize rapidly not only because of size but to maintain body temperature because the large ratio of surface to volume means a great heat loss b Active metabolism rate is variable but is generally considered to be about 2 X BMR c Poikilotherm s BMR varies with temperature Q10 2 d Precise limits depend on enzyme adaptations to temperature some enzymes are adapted to cold others to hot conditions e Why be a homoiotherm It allows effective food getting Early bird gets the worm Homoiotherms can be very active in the dawn and also at night Moreover homoiotherms have higher digestion rates 8590 because enzymes work efficiently at a set high temperature 23 f Poikilotherms conserve energy but have slow metabolisms at low temperatures Because of the varying temperatures on enzymes poikilotherms have lower digestion rates eg Grasshopper 30 Snail 45 Daphnia zooplankton 13 E Ecological Efficiencies in ecosystems 1 Transeau 1926 first to consider energy use in nature studied a Corn eld in Illinois Measured the enegy input and calculated the efficiency of the plants use of the sun s energy Juday 1940 took an ecosystem approach and calculated the energy budget of Lake Mendota both physical and biological Accuracy of course not high but represented the first attempt to think about an ecosystem in terms of energy Lindemann a young man was stimulated by Hutchinson to study energy flow In 1942 he wrote an important paper on idea of ecological efficiency and developed the concepts of Trophic levels and the efficiency of the ow of energy through levels We call these Lindemann Efficiencies in honor of him He wrote only a few papers as he died of hepatitis but he is among the most famous of ecologists because of his theoretical insights I Energy uptake P Production A Assimilation R Respiration All kinds of ratios can be calculated as shown in this table from the textbook Can be eXpressed as within trophic levels and between trophic levels 6There is much variation among different organismsin energy use but for trophic level transfer L is a good average for energy N U 1 kJI ow 7 Odum s Silver Springs Study is a good example Trophic level I II III IV 20810 NPP 5 3368 16 383 11 21 410000 GPP 20810 3368 383 F Detrital food chains versus grazing food chains 1 Here the primary consumers largely bacteria amp fungi which animals eat animals cannot digest cellulose amp there not enough nitrogen in dead plant matter See chapter 9 in Smith It is very difficult to measure biomass amp metabolism of detritivores esp microbes the bacteria and fungi CompleX symbioses of microbes with animals Coprophagy animals eat feces of other animals to digest microbes amp fungi Whittaker amp Woodwell In OakPine Forest on Long Island at the Brookhaven Atomic Lab were asked by the AEC to study the effects of radiation on ecosystems a First was the direct effects of radiation using caesiumit kills and the more interesting the more beautiful the more useful organisms are the more susceptible b Second was the most surprising discovery was the path of radioactivity in organisms in the food chain Done to show the effects of fallout but it illuminated energy ow in forests hWN Trophic Level I GramCal M2 NPP 1200 gt 500 Wood 50 Humus Not Consumed in study GPF 2650 6701ngested 31 root t1ps 3601eaf11tter amp tw1gs Trophic Level II 50 not assimilated difficulttodigest lignins to humus above P 8c Biophage food chain 30 Saprophage food chain Fungi and Bacteria 3 70 Microarthropods and Worm 250 Difficult to exactly place the energy use in Trophic level II or III 5 Why have detritus not biophage food chains Consider plants compete against each other and to grow into a competitive tree a plant mustnot be eaten to accumulate the biomass to compete for light and for nutrients under ground Therefore plants defend themselves with poisons cellulose no sodium poor amino acid ratiosimaking it difficult for animals to live on plants When plants drop their leaves all possible soluble nutrients are withdrawn leaving a very unnutritious husk with cellullose amp lignins Many aquatic environment this organic matter may accumulates as peat because the lack of oxygen prevents complete decomposition this is the source of coal in the sea as oil Obvious that the more valuable the biomass the more protected it is plant poisons spines etc is to inhibit herbivoresanimal and microbial 10 Note that in grass the underground parts protected above parts eXpendable and therefore burns ridding the prairie of competition with shrubs and trees 11 Animal are very important because the power of movement allows masticulationchewing and grinding as in termites where it is a three way mutualism between termite protozoa and bacteria in ruminants the stomach acts as a fermentation vat for microbes to digest the cellulose the caecum of the large intestine similarly acts as a fermentation chamber P 8b 12 Many insects have microbes within their bodies in mycetomes that provide amino acids and vitamins not in diet O l 00 D I General Symbiosis A Symbiosis as originally de ned by Heinrich De Bary 1879 who was studying lichens is a definite adaptive relationship between two species with one living on in or with another species either continuously or periodically and with at least one species bene ting from the relationship 1 2 3 Textbook popularizers often de ne symbiosis as being of mutual benefitJIhis is only one type mutualism which need not be symbiotic Free living mutualists are common and very important in ecosystem functioning Protocooperation is the more general dependence of all the organisms of an ecosystem on each other B Adaptation types N E 4 V39 0 gt1 Considered in the evolutionary sense we can anticipate all sorts of degrees of adaptation Peter Price in his textbook on insect ecology stated that the majority of species were symbiotic in role especially the parasitic mode A species may visit another species frequently and even though it has signi cance e g mosquito biting and sucking blood vertebrate eating fruit or pollinators visiting owers there were no symbiosis no living on in or with the other species Symbionts may live with the other species eg in sharing a nest or hole niticolous organisms Symbionts may also live continuously on the other organism host as an external symbiont or ectosymbiont also called an epibiont epiphyte or epizooite Or symbionts may live continuously inside host as an endosymbiont a In host intestines or other cavities of the host b Or in the blood or tissues of host actually inside the host A symbiont may be facultative lichens and Spanish moss can exist equally well on a tree or telephone wires or obligate requiring a specific host In cases as where the male lives attached in the female s reproductive tract the echiuroid worm Bonellia or attached to the female some angler shes these are not parasites because they are the same species 8 Similarly in viviparous species females with placental development the fetus is not a parasite because again as it ofthe same species 9 In some birds a female may sneak her egg into the nest of another female of the same species so the other female raises it but again this is not parasitism It must be of another species when it is called brood parasitism C Speci city 1 May be functionally significant but the precise identity of the host may be unimportant a nonspecific host relationship a facultative one as in many epiphytic plants 2 Varying degrees of host specificity E May be family generic or even specieslevel host specificity by the symbiont Fquot Specificity is often the consequence of the symbiont adapting to overcome host resistance sometimes the symbiont even shows the host is a sibling species of another species 0 Specificity can be phylogenetically revealing as when the host and symbiont evolve together Sometimes the symbiont may evolve more rapidly or there may be a host transfer to complicate things D Symbiotic relationships living on in or with another species 1 Commensalism an association between members of different species in which one the commensal lives on in or with the host but does not feed on the host but benefits in other ways as a place to live for photosynthesis to catch food even share the leftovers Smiths for some reason do not discuss this relationship yet it is very important ecologically speaking in ecosystems Commensalism literally means to share the table 2 Parasitism an association between two species in which one the parasite lives on in or with the host and feeds on its host without killing it As Elton said It lives on the interest not the capital or as an old story put it It does not kill the goose that lays the golden eggs 3 Mutualism a close association between members of different species that benefit both Symbiotic mutualists live on in or with each other Freeliving or nonsymbiotic mutualists both benefit such as in frugivory or pollination 4 Symbiont often used for an organism that lives in close association with a member of another species but the exact nature of the symbiosis is unknown or ambiguous or subject to change This often used to refer to a microorganism living in an uncertain or variable relationship with a larger host organism For example a bacterium living in the gut may be mutualistic in producing B vitamins if the host is low in vitamins or it would functionally a commensal if the host is already well supplied with B vitamins or if the host is starving the bacterium may then become parasitic taking nourishment from the host Changes in host resistance due to disease such as AIDS that destroys the immune system may also change the symbiotic relationship E Amensalism or antibiosis It means to keep off the table A species may be able to harm another species eat it or harmfully live on it but is prevented from doing so by the potential host s resistance E 4 V39 0 gt1 This is the antithesis of symbiosis since there is not even a temporary living together rather a keeping of the other organism away Antibiotics many fungi algae and bacteria produce chemicals that inhibit the growth of their competitors Fungal chemicals are often used by humans as antibiotics of medicine As eukaryotic biochemistry is different from prokaryotic biochemistry we can use the fungal defenses to fight prokaryotic diseases This is what Fleming discovered with the mold Penicillium on a medium thereby discovering the antibiotic penicillin Allelopathic compounds Plants such as creosote bush and black walnut produce chemicals that drive plant competitors out even seedlings of their own species intraspecif1c amensalism Socalled secondary plant compounds alkaloids quinine pyrethrum and many others are poisonous and or act as feeding inhibitors against insects and fungi Animal chemicals and toxins and that keep other animals away are called allochemics as the skunk s defense odor and repugnatory sprays of bugs and many beetles Vertebrates have perfected a remarkable defense system known as the immune system in which nonself chemicals antigens are attacked by antibodies the immunoglobulins One immunoglobulin E mounts an attack on parasites which immune attack can be so vigorous that mistakes are made and the host may die Insects in defense against parasitoid parasites within them try to wall off the parasite with a protein covering 8 General defensive morphology behavior and in plants the presence of thorns and spines function to inhibit biophages and the pedicellaria of Echinodermata and avicularia of Byrozoa are amensal 7 they keep the fouling commensal organisms off 9 In this sense all antipredator and antiherbivore defenses are amensal including mimicry as was discussed under predatorpreytrophic eXpoitation relationships 11 Commensalism Van Beneden 1876 stated requires from his neighbor a simple place or boards his vessel and does not partake of his provisions i e a messmate not at the expense of the host does not feed on the host literally at the same table A Lives with the host not on the host 1 Inquilines live in nests and burrows the host simply provides shelter referred to as an Innkeeper Symbiosis a Many annelid worms such as the lugworm Arenicola make Ushaped tubes in the sedimentand so provides ventilation and food supplies for the little pea crab Pinnixiathat shares the tube b Holes made by burrowing animals such as gophers ground squirrels etc provide homes for many commensals especially insects c Social insects the ants bees wasps and termite build complex nests diverse set of inquilines or niticolessynoeketes synoeketes are toleratedaccepted by the host species d Human guests house mouse house centipede house spiders house sparrow booklice rats cockroaches dog and cat and other pets in house all can be seen as commensals 2 Companion commensals a Pilot sh attends sharks or other large carnivore not live on it It remarkably can swim directly in front of the predator When the predator makes a kill the pilot fish helps itself to the left overs b Hyena attends lions eats what lions do not want such as bones that hyenas break open c Dogs cats live with man mostly commensalistic nowadays as pets but can be mutualistic as in the case of herding and hunting dogs and the mousehunting abilities of cats d Cattle egrets accompany large ungulates and bene t from the stirring up of insects and perhaps greater safety with large animals Cowbirds also have this habit and similarly accompany grazing ungulates B Temporary contact 1 Remoras are sh with a sucker on the top of its head that they use hitchhike rides on sharks dolphins whales sea turtles These sh let go to get free meals of leftovers from the catch of the larger sh Some species may also feed on parasites of their ride ie act as cleaners which would make these mutualistic Recognize that is includes phoresy as a bene t to the remoras 2 The little pilot sh swims in front of the nose of a large sh looking like it is guiding the sh when actually it is accompanying the sh When the big sh makes a kill the small sh helps itself to left overs 3 Some polychaete worms live on or in a shell occupied by a hermit crab Pagurus and shares meals with crabs It is not really on host so it is a almost a messmate commensal 3 Phoresy using another species for dispersal a Pseudoscorpions and mites take rides on large ying insects b Pseudoscorpions are famous for climbing owers to take rides on bees and ies This helps to understand the large geographical ranges of many pseudoscorpions Seeds sticktights burrs are adapted for catching on fur and our clothes for dispersal c Small ies on dung beetles or mites on burying beetles get a free ride to Q dung or corpse and share in the food Some mites eat eggs of ies that compete for food with the beetles so this can be mutualistic or commensalistic depending on the exact relationship A parasitic y Dermatobium hominis remarkably lays its eggs on mosquitoes and the mosquito carries eggs to the host where the egg hatches and burrows into the host often man Your professor had onc during field work in Brazil C Permanent contact Epibionts 1 On trees lichens orchids bromeliads birds etc some facultative others obligate 2 Aufwuchs or periphyton on aquatic plants 3 Coral and oyster reef a maze of commensalism algae sponges hydroids worms mollusks tunicates all living on or among each other 4 Sponges regular hotel of crannies and holes 5 Obligate algae a Basicladia is found on turtles here in Texas b Rhizoclonium is on the turtle C hrysemys c An hostspecific alga is found on Sloths but see under Mutualism 6 Commensal Bamacles live on animals and have to overcome the host resistance to their living on the surface of the host so are usually hostspecific There are a large number of commensal bamacles of which is mentioned a Alepas is found on sharks b C helonobia testudinaria found on sea turtles and C patula is found on blue crabs Obviously a big host transfer here c Coronula is foundon whales and the pattern of the bamacles on the skin of the whale is used to recognize individual whales d This type of a relationship can and has readily evolved into parasitism as food is underneath D Pennanth contact endosymbionts found in cavities in the host 1 Pinnotheres sp crabs live in mussels such as M ytz39lus adults and in oyster s Crassostrea virginica mantle cavity but do not eat the clam 2 Freshwater clams similarly have large water mites living as commensals in mantle 3 Small fish live with anemones jelly fish and siphonophores which is remarkable as the cnidarians normally catch small fish paralyzing them with powerful stinging cnidoblasts after which is the phylum name Cnidaria a The fish Discosoma lives inside of large anemones and comes out to feed and darts back when threatened but any wrong fish is attacked by the anemone b Nomeus lives with Physalia the PortugueseManO War c F ierafer lives in anal cavity of sea cucumbers Holothuroidea and comes out to feed when it s safe d Pearl sh lives by day in respiratory tree of sea cucumbers and at night comes out to forage for food 4 Pinnaxodes oridensis is a crab that is similarly found in the respiratory tree of a sea cucumber Theelothuria princeps V39 Bacteria protozoans and worms are commonly found in digestive tracts may do no harm whatever be simply commensals esp in large intestines 0 Pitcher plants 7 Despite these plants being carnivorous insect larvae are found living in the pitchers e g some midges Chironomidae mosquitoes Culicidae and moths Lepidoptera although the latter moth is more of parasite feeding on the plants 1 There is also a remarkable treehole fauna and the phytotelmata Tank plants orchids bromeliads etc which have a rich biota of algae insects and amphibians that were discussed in Freshwater Ecology III Parasitism A General 7 These are symbionts that feed on the host but do not kill it so are symbiotic partivores not predators 1 Types Hosts are walking zoos a Endoparasites these live inside the host 7 tapeworms ukes nematodes fungi bacteria True endoparasites live within the tissues of the host b Ectoparasites live on the outside of the host ticks fleas mange mites lice c Cavity parasites in mouth ear and digestive tract not truly within the host as a tissue parasite isimost ukes tapeworms nematodes many microbes fall in this category d Another division is between macroparasitesimetazoan animals and the microparasites viruses bacteria fungi and protozoans e Some parasites are nest parasites and live in nests and suck blood as do eas and kissing bugs that is they live with the host rather than on or in the host being on the host only to feed 2 A parasite lives off its host and adapts to host defenses 7 finely controlled partivory to live off the host but not kill it 3 This relationship leads to much host speci city through coevolution between the host defenses and the parasites exploitation of the host B Evolution of Parasitism l Commensal route This is a short path to parasitism E Fquot 0 3 1 3 1 Bamacles many are parasites Sacculina on blue crabs is so modi ed for endoparasitic life that it was not recognizable as a arthropod until the larval form was found It looks like a mycelium within the crab Mistletoe which lives on trees is a hemiparasite as is Castelleja the paint brush which is a root parasite These are halfway to being a parasite in that they photosynthesize but do steal nutrients and water from the host plant Other mistletoes are holoparasites in being entirely parasitic and having no chlorophyll Indian pipes This is a colorless vascular plant of the family Ericaceae that remarkably parasitizes its own fungal mycorrhizae The squawroot Fig 172 in Smiths is listed in your text as a hemiparasite but is in fact a parasite feeding on the roots of oak trees In digestive tracts many bacteria can have any role ranging from commensals to parasites to mutualistic depending on nutrients and status of host Even different strains of E 001139 will cause distress in people not adapted to the microbe as we all know 2 Partivore route do not consume host just eat part of the host When the host organism is large there are many opportunities for evolution of parasitism a Camivorepartivore route mosquitoes as compared to eas The mosquito merely Visits to sucks blood it is not a parasite as it does not live on in or with the host However eas which live on hosts and especially live in the nests are parasites b Herbivore pa1tivore route gallforming insects Fig 1710 aphids leaf miners and plant nematodes are parasitic in living on or in the host plant c Peter Price in his Insect Ecology book thus argues that most herbivorous insects are functionally parasites because they live on the host and feed on the host as larvae which is the growth stage ecologically different from the adult which is free living adapted for reproduction and dispersal and usually is flowerfeeding C Parasitoid insects 1 These are the larvae of many families of Hymenoptera and larvae of the insect family T achinidae As they go through life cycle they begin as a parasite but since they do kill their host they are better called parasitoid predators 2 Hyperparasitism may have up to 3 levels of parasitoids that is the parasitic larva is itself parasitized by a smaller wasp larva 3 There are an enormous number of ies and wasps many whole families that are parasitic as larvae on insects but are ower feeders as adults These insects are much used by entomologists in 1PM integrated pest management control to help reduce reliance on insecticides D Phoretic Parasitism for dispersal l Glochidium This is the larval stage of freshwater unionid and mutelid clams 2 Gochidia are parasitic on the gills and body of fish After a short development period during which they are transported by the fish the glochidia drop to the bottom and become filterfeeding clams This a clever strategy to get upstream a problem for mollusks 3 Chigger This is the first nymphal stage of a mite that takes a blood meal on vertebrates including us and importantly gets a free ride The adult is free living carnivore the red velvet mites of the family Trombiculidae The terrible itching of chiggers is not the animal but the stylostome a feeding cone of saliva left behind in the skin which drives your immune system and you crazy 3 Horsehair worms Phylum Nematomorpha have an unusual life cycle in that the larvae are parasitic in terrestrial arthropods such as grasshoppers but the conspicuous free living adult worms live in freshwater have vestigial digestive tracts and do not feed but only reproduce and the eggs have to get to the host insect to parasitize it For the worm the grasshopper must get to water for the life cycle to be completed E Host Parasite Relationships 1 Superparasitism This is an overparasitism that can kill the host This is rare in macroparasites and is avoided by having mechanisms to allow the eggs to be able to leave the original host and n0t hatch in the host If they did it would easily cause superparasitism 2 An ideal parasite is one that can survive in its host without substantially weakening it thus allowing the host to complete successfully with others of the same or different species This would allow the parasite to successfully complete its life cycle and start a new generation Remember the Goose and the golden eggs E If host is weak has poor defenses is under too much stress it may become overparasitized and die Some unusual parasites may even render the host sterile This is not a good strategy for parasite survival 4 If populations in the host become too dense microparasites as bacteria and viruses may sweep through the host population epizootics in animals epidemics in human UI Generally when the host is greatly harmed it means that the parasite is infecting an organism that is not its normal host Disease condition as in the case of AIDS Most human diseases appear to host transfers from some other animal as in the case of in uenza from pigs or encephalitis from birds 0 Alternating life cycles promote control of excess reproduction in host and provide for finding the correct host a In animal macroparasites sexual reproduction occurs in the definitive host usually a vertebrate and asexual reproduction occurs in the intermediate host usually an invertebrate iof ten a mollusk and the return to the definitive host often goes through a second intermediate host Interestingly the same pattern is found in some parasitic fungi A famous example in class Basidiomycetes is the pine blister rust that damages Pine trees The alternative host of the fungus lives on the gooseberry and currant shrubs Ribes See pg 310312 in Smiths for examples of complex parasitic life cycles from animals and fungi Puccinia graminis is another rust that is a serious pest on cereals and the alternate host is Berberis the barberry Such complicated life cycles require high fecundity for parasites to find the hosts It serves to reduce intraspeci c competition among life cycle stages to have definitive sexual hosts and intermediate asexual hosts Fquot 0 3 1 7 Vectors serve to allow the parasites to get to the correct definite hosts andor to intermediate hosts by using trophic and habitat relations between the host species Often bloodsucking insects are vectors that achieve transfer of disease microbes for example in humans a Malaria Plasmodium a protozoan disease is carried by some species of the mosquito Anopheles a Yellow fever a virus is carried by species of the mosquito Aedes 8 9 Fquot Encephalitis a virus of birds deadly to humans is transmitted by the mosquito Culex which also carries distemper a mild human disease which however is deadly to your cat 0 Black ies Simuliidae in Africa transmit a nematode that causes oncoceriasis river blindness 3 1 The Tse tse y transmits a protozoan T rypanosomathat causes sleeping sickness in Africa In the New World Trypanosoma is transmitted by bloodsucking bugs Triatoma D Deer ticks are now causing a serious problem in the Eastern USA by transmitting a spirochaete bacterium causing Lyme Disease named after a location in Connecticut where is first became serious Practically all species are probably parasitized but the incidence variety and speci city of parasites varies from species to species a Size of host important as larger hosts means more biomass utilizable and the more habitat types available b The abundance of the host since the more abundant it is the easier it is for the parasite to nd it c Heavily parasitized host often display abnormal behaviors that may promote the transmission of the disease as in case of rabid dogs Some intermediate parasites may manipulate the behavior of the host to facilitate transfer to the definite host as in Fundulusshore bird system in California Pg 317 in Smiths It needs to be stressed that great variety of fungi especially Ascomycetes and Basidiomycetes are obligative parasites on vascular plants eg rusts and smuts many of which have compleX life cycles with definite and intermediate hosts Other fungi will have a single host The fungi therefore not only decomposers but can be active herbivores and the death of trees is often caused by fungi as in the Dutch Elm disease and the Chestnut Blight Both of these are species adapted to a different host and transferred to a susceptible host It also needs to be stressed that most of the small when compared to the size of the vascular plant insect herbivores are actually functional paras1tes and exhibit the high degree of host specificity characteristic of parasites as discussed earlier in the evolution of the apple maggot Some are ectoparasitic and others endoparasitic living within the host The tremendous diversity of the class Insecta is in large part the result of this relationship with the vascular plants The weevil family Curculionidae is so large larger with 60000 species than the whole Phylum Chordata because the larvae live on particular host plants and in particular places within the plant as in buds roots seeds etc As the air medium is difficult one for dispersal in terrestrial environments many tissue and gut parasites have evolved compleX life cycle systems many of which take advantage ying aquatic insects as vectors for transmission of the parasite from aquatic systems where the alternate host lives to the terrestrial de nitive host Small herbivores such as insects have relatively few macroparasites although certainty are parasitized by many protozoans fungal bacterial and viral diseases as well as by parasitoid insects which however ecologically function more like predators D Social Parasitism l 2 E Kleptoparasitism robber parasitism stealing food from other species a Skuas bald eagles rob other birds of their food facultative b Hyenas 7 sometimes steal from lions facultative c Predacious ies often follow army ants around and steal food from them d Robber bees mimic bees and steal honey from them Brood Parasitism a Cuckoo in Europe cowbird in N America honey guide in Africa lay their eggs in the nests of other species of birds Can be a serious pest as in the cowbird in the Eastern USA promoting some warbler species to become endangered Fquot Slavery in ants some species never build their own nests but utilize other ant species An invading queen kills the real queen of the nest and takes over She and her lazy brood are reared by the enslaved ants Her brood leave to locate other nests to parasitize c There are also cuckoo bees that similarly take over bee hives Inquilines live in nests of social insectsiants termites bees and wasps The social insects vigilantly guard their colonies and kill intruders but are not 100 effective Some species are able to get in and take advantage of the colony Some as mentioned are merely commensals These invaders are mostly other insects especially beetles Many species take advantage of IV trophyllaxis in which the social insects pass food droplets to each other and essentially get in to the serving lane which borders on parasitism Inquilines fall into three groups a Synechtrans robbers with no special devices hit and run invaders These are closer to predators only in the social context are they parasites of the colony Fquot Smoeketes Hosts cannot recognize these as intruders and essentially leave them alone to live in the nest These inquilines may be commensal parasitic or even mutualistic in cleaning the nests c Smph es are cared for often nourished by social insects For example The rove beetle Atemeles pubicollz39s lays its eggs in the nest of the ant Formica polyctena The Atemeles larvae release a pheromone that causes the ants to treat it as their own even while the beetle larva feeds on the eggs and ant larvae and even begs for food by trophyllaxis When it becomes an adult it mimics food begging behavior of the adult ants The female Atemeles adults leaves the Formica nest to find aMyrmica ant nest the M yrmica ants continue brood activity throughout the winter which assures the beetle better food service The rove beetle produces chemicals to appease the new host species The beetle returns to the F ormicg ant nest in the spring to lay eggs and start the cycle over Mutualism varies in degree of contact and advantages derived A To understand the true extend of mutualism both symbiotic and freeliving it is important to realize the degree in which ecosystems function through the combined activities of the major groups of organisms N L 4 The Kingdom Animalia these have muscles for locomotion and mastication and often have very large body size Included here are the heterotrophic Protista The Kingdom Plantae these photosynthesize and often have very large body size Included here are the photosynthetic Protista the algae The Kingdom Fungi These have wonderful powers of absorption of nutrients and water and are good chemists The Kingdom Bacteria These are the superb chemists capable of nitrogen fixation and carry out many chemosynthetic reactions necessary for ecosystem functioning Moreover many bacteria are extremophiles that can live in environments that so other organisms can live in like hot springs 5 So in the broadest sense of the word ecosystems are mutualistic an understanding that becomes deeper when one considers the Gaia Hypothesis of the world ecosystem as being a selfregulating selfenduring entity 6 Therefore on the level of species interactions ecosystems show much protocooperation beneficial relationships that are facultative and not symbiotic We will look at some ofthe important species to species interactions both free living and symbiotic B Relationships involving fungi as absorbers and plants as photosynthesizes l Lichens Ascomycetes form structures in which green or rarely bluegreen algal cells are imbedded basically a fungus farming algae E Fquot The lichen symbiosis allows survival even under the harshest conditions deserts and tundra so maybe even on Mars lichens could survive Odd they cannot handle humancaused air pollution Helotism a symbiotic relationship in which one member functions as the slave of the other The lichen fungus seems to be in control and gets the most benefit from the association and the alga may seem enslaved However the alga gets some protection from desiccation and moisture and may benefit from the superior power of the fungus to absorb nutrients for the benefit of the fungus 2 Mycorrhizae fungal roots a Fungal mycelia coat the root tips of many plants aid in the uptake of mineral nutrients and water form a physical barrier to pathogens and even secrete antibiotics in return the fungus gets carbohydrates made by the plant All conifers all maples heath oaks beeches all orchids orchid seeds cannot even germinate without them 75 of owering plants have mycorrizae A study in Japan of 134 families of plants showed that 82 were mycorrhizal One authority believes that all woody plants are mycorrhizal Mycorrhizae are especially important in the tropics since this allows high productivity on poor soil by rapidly recycling nutrients to the host plant as the nutrients become available through decomposition Indian pipes 7 Remarkably this plant apparently parasitizes its own mycorrhizae the Indian pipe is an angiosperm related to azaleas blueberries and cranberries The plant is white without chlorophyll thus the mycorrhizae do all the work and apparently get nothing in return so is this parasitism or does the fungus get some advantage 4 Plants using fungi for Defense In several grasses that were infected with an ascomycete fungus Acremonium it was discovered that cattle suffered toxic effects Fig 1721 in Smiths Similarly in some lawn grasses that were resistant to chinch bugs it was discovered that the resistance was based on the presence of a toxic fungus that thus benefited the grass B Relationships involving animals as hosts with algae within 01 on metabolicnutrients l Endosymbiotic algae Zooxanthellae are algal cells that are yellow to greenish color of the Division Chrysophyta and Pyrrophyta dino agellates Zoochlorellae are algal cells pale to bright green in color in the Division Chlorophyta Cyanellae are algal cells bluishgreen in color of the Division Cyanophyta This relationship is common especially in the marine habitat where they algae live with in the tissues of the animals A few important examples follow a Coral symbionts Symbiodim39um a dino agellate zooxanthellae of coral animals that are polyps of a cnidaria animal Symbiodinium supplies oxygen food and use up carbon dioxide and nitrogen from tissues and promotes chemical conditions that allows abundant calcium carbonate deposition 39 The coral polyp provides a substrate carbon dioxide nutrients and nitrogen from their predation on zooplankton 39 39 This relationship efficiently cycles nutrients and allows coral reef formation by changing chemical conditions in the coral polyps so that they lay down calcium carbonates b T ridacna giant bear s claw clam of the South Paci c up to a meter wide Amoebocytes of the clam harvest the zooxanthellae that grow in the mantle c Widespread presence of algae in animal tissues some atworms eg Convoluta does not have to eat gets food and oxygen from its alga Carterz39a hydra amoeba paramecium foraminifera radiolarians sponges jellyfish annelids tunicates rotifers echinoderms molluscs all known to have mutualistic algae D quot1 Frog eggs develop better with algae in egg envelope than eggs without algae Recall that Chlorohydra outcompetes Hydra in sunlight loses in the dark 2 Evolution of eucaryotes from procaryotes is called the Serial Endosymbiosis Theory of the Origin of Eukaryotic Cells It states that an anaerobic cell that engulfed food was once invaded by bacteria and those bacteria ultimately became organelles such as mitochondria and chloroplasts Even the cilia and agella appear to be derived from bacteria This is clearly the world s greatest mutualism the origin of Animals Plants and Fungi begin with this 3 Camou aging symbioses a b Sloth s algae being green like canopy the sloth is more protected Many epibionts are probably tolerated and promoted for this reason c Some crabs called decorator crabs put pieces of algae and the like on the outside of their bodies This is research carried out by our invertebrate biologist Dr Mary Wicksten C Microbial symbiosis for metabolic specialities l Nitrogenfixing bacteria in root nodules e g Rhizobium reduce atmospheric nitrogen to fixed nitrogenammonia and either organism can use the ammonium ion for synthesizing nitrogenous organic compoundsiproteins and nucleic acids The plant essentially feeds its bacteria in the nodules 2 Mycetomes special animal organs to house a microbeyeasts or bacteria E Fquot 0 3 1 Supply nutrients that the animal is de cient in The bacteria of the mycetomes yields vitamins and essential amino acids and in insects steroids The animal in turn feeds the microbes Thus we have beetles thriving on white our or cellulose that the bacteria decomposes a diet that would kill ordinary animals lacking the microbes 3 Gut symbionts breakdown cellulose and supply vitamins very necessary since animals cannot digest cellulose E Ruminant ungulates protozoans and anaerobic bacteria in rumen and reticulum ferment food which is then regurgitated chewing cud swallowed to omasum then finally abomasum where nutrients are absorbed the symbiotic bacteria can synthesize from urea and ammonia the amino acids the animal needs to make proteins b Large intestine of nonruminants bacteria in caecum serves this function This is why rabbits have two types of feces Soft feces that are eaten to obtain nutrients and hard feces that are the true feces c Termites agellate protozoa Polymastinina and Hypermastigina live in the termite hind gutboth known from nowhere else when the termites molt they shed the lining of hindgut which has the protozoa and termites must eat their exuvia to reinfect themselves Actually the protozoans themselves cannot digest cellulose but their bacteria digest the cellulose in their food vacuoles 4 Agriculture fungi culture a Termites of subfamily Macrotermitinae and ants of the tribe Attini leaf cutter cultivate particular fungi on leaves and wood in their nests They keep food moist fertilize it and secrete chemicals that inhibit the growth of other fungi and bacteria Termites harvest the fungus as bromatia which are bitesized clumps of fungi caused to form by chemical excretions of the termites b Ambrosia bark beetles inoculate wood with fungi and the larvae feed on fungi that grow within the tunnels One an ascomycete Ceratocystis ulmi causes the Dutch Elm Disease which threatens the American Elm with extinction D Animal Mutualism l Motility and protection a Pagurids and anemones the hermit crab Eupagurus prideauXi carries the anemone Adamsia palliata on its back b Lymnaea a snail and Hydra live together C Sponges on pagurids also sponges are the skunks of the sea 2 Protection and bait a Fish in coral reefs on anemones Discosoma and Amphz39prion live inside the anemones without being harmed and may even attract prey shto the anemone So perhaps this is a mutualistic rather than commensal relationship b Physalia Portuguese manofwar also has attendant sh Nomeus that is immune to stings lives in tentacles lure other sh into them and feeds on table scraps of Physalz39a 3 Mutual protection Plesiobiosis a Mixed ocks and herds as on the African Savanna Why aggregate together b The answer appears to be that many eyes ears olfaction etc zebra nds water helps the entire herd to servive c Orioles and bees live together as bees repel parasitic ies and orioles help defend bees from honey stealers 4 Cleaning symbiosis a Small fish wrasse and shrimp form cleaning stations where other large sh will gather to be cleaned of fungus parasites even have wounds cleaned The peppermint shrimp is a famous example one species of which lives in Texas jetties b Ox bird and ectoparasites of ungulates Egyptian plover removes leeches from gums of crocodiles and even acts as lookout for danger Similarly the tick bird and rhinoceros associate 7the bird gets food and protection rhino gets rid of ticks and has a early warning of danger c Nest cleaners Female hombill is sealed by her mate into a hole in a tree He feeds her through a slit in the seal The nest is kept clean by an army of small insects that thus are not commensals but mutualists d Many of the small arthropods synoeketes living in social insect nests are nest cleaners and very important for the health of the colony 5 Domestication animal husbandry a Ants tend aphids scales and some caterpillars for sweet secretions Ants vigorously protect their insects May even take them underground in the winter bring them back out in the spring Often ants will eat some of their domesticated insects b Humans domesticated livestock Sometimes the livestock can no longer survive on their own so it becomes a mutualistic rather than a predatory relationship The same can be said of domesticated plants many of which such as corn cannot live in nature anymore E Animal vascular plant symbiosis l Acacia Acacia corm39 era and ants Pseudomvrmex m39 rocincta the ants get food from extra oral nectaries and Beltian bodies swollen nutrient rich leaf tips and shelter hollow thorns in which they live The acacias get protection since the ants discourage herbivores from feeding on them Daniel Janzen has shown that without the ants the tree will die within a few months due to fungal and vine growth and increased herbivore activity The ants protect the tree by their vigorous removal of all foreign material dust pollen fungal spores spider webs other insects their attacks on herbivores and their destruction on seedlings under the host tree Acacias without ants have secondary plant compounds cyanides that ant acacias do not have 2 Vascular plants Homoptera Nectar Extra oral nectaries a Evolution of higher insects into separate ecological niches from the larvae is plainly traceable to the secretion of sugar water by sucking insects The insects need protein not sugar and so secrete the excess sugar water after processing the sap for protein This sugar is fuel for the ying machines b This process led to the plants secreting nectar themselves leading to the evolution of extra oral nectarines and then oral nectar leading to pollination by animals 3 Pollination 80 of owering plants are pollinated by animals wind pollination has been shown to be secondarily evolved in owering plants a Fquot 0 Many insect orders especially the higher insects that have a complete metamorphosis Holometabola are involved in pollination Probably well over half of all adult insects are ower feeders This allowed the evolution of the strategy of larvae feeding on plants and the adults specializing for dispersal and reproduction This is coevolution on a grand scale the owers and insects evolution of complexity in owers and the evolution of the complex nervous system in insects Story of Yucca moth Tegeticula Birds and bats have also coevolved with owers bright red owers hummingbirds Bat owers white or greenish owers as bats like most mammals do not see colors The bat ower smells like an animal cage 4 5 d Pollen transport is the advantage by phoresy and is worth the costs of making owers and nectar Fruits seed dispersal by frugivorous animals a Dispersal very important either by attaching to the animal Commensalism or by having edible fruit around the seed as bait to attract and animal to eat the fruit and disperse the seeds Fquot Some seeds need to transverse the vertebrate gut to sprout eg the Dodo bird and Dragon tree The Dodo was hunted into extinction on Mauritius in the Indian Ocean The dragon trees had big fruits the trees were 300 yrs old but none of the seeds sprouted EXperimenters brought in turkeys to eat the dragon tree fruits first new trees in hundreds of years The seeds were roughed in the gizzard which prepared them to spout Spore dispersal sweet or smelly fungi attract insects ies eg Phallus impudius V The complexity of symbiotic relationships A An African bird the honey guide 1 N E Mutualism the honey guide woodpecker family and the honey badger or ratel weasel family the honey guide finds the beehive or termite mound and leads the ratel to it After the ratel tears into it both will feast the bird eats the insect larvae and the honeycomb the ratel eats the honey and the insects If the honey guide cannot find a ratel it has been known to use baboons or even humans to serve as a guide Mutualism the honey guide cannot digest waX but has bacteria in gut that can break it down so it can be absorbed by the bird The bacteria get food and shelter the bird gets nourishment Parasitism the honey guide is a brood parasite parasitic nester She lays her egg in the unattended nest of another species of woodpecker The young honey guide kills its nestmates and alone is fed by its surrogate mother B Mycorrhizae truf es and mice 1 The truf e is a the fruiting body of a basidiomycete fungus that is a mycorrhizae on the tree 2 Why is the truf e underground 3 Mice smell the truf e and dig down to eat it This is part ofthe reason the truf e is prized for its great avor 4 The mice disperse the spores of the fungus in its fecal pellets 5 Humans in Europe use pigs or dogs to locate the truf e stealing from the mice L2 15 Terrestrial Ecology II Pedology Soil Science I Introduction A General 1 Many ecology textbooks as in Smith and Smith treat soil science as a separate entity from terrestrial ecology placing it among the physical factors Yet the soil is clearly a very necessary and important part of terrestrial ecology Indeed the genesis of soil is linked to the terrestrial plants 2 Russians dominated the study of soils especially Dokuchayev 1846 1903 until the Russian Revolution exterminated the educated aristocracy that included most of the scientists I prefer the Russian system of soil classification as compared to the American system as it is more ecological in its orientation The American system is more oriented to the physical properties of the soil B Dokuchayev recognized that these were five factors involved in soil formation or Pedogenesis 1 Climate 2 Vegetation and other organisms microbes and animals 3 Parent rocks source materials 4 Topography and drainage agents of erosion 5 Time it takes a long time to create a soil II Origin of soil A Sources of soil primary and secondary soils Primary weathering of bedrocks both physical and chemical is promoted by plants and microbes Soils produced directly from bedrocks are called primary soils Source materials produced by erosion and transported elsewhere form secondary soils Bedrocks originating from igneous magma and highly heated and changed rocks a Granite gt sandy acid soil b Basalt gt basic clayey soil c Serpentine rocks gt soils with unusual chemistry high in nickel and manganese unusual plants are adapted to these strange soils d Metamorphic rocks are primary rocks regenerated from sedimentary rocks by heat and pressure such as marble and slate Sedimentary rocks are formed from transported materials produced by erosion and changed into a rock by heat and pressure These break down to form soils whose characteristics derive from the original products of erosion Limestone gt Calcareous Soils b Shales gt Clayey argillaceous soils B c Sandstone gt Sandy arenaceous soils 4 Secondary soils transported and deposited soils a Wind gt loess fine soils aolian soils from blowing sand as in dunes b River flood plains gt alluvial soils c Lacustrine lake soi d Glacial till soils of mixed sized substrate of gravel sand and rocks dumped by glaciers in moraines e Marine sediments Clayey calcareous soils f Peat organic soils derived plant debris Soil Development or formation similar to a succession in vegetation development to climax and has soil parallels It is important to realize that without a plant cover the soil would quickly erode away by water and wind Plants are essential for the development and maintenance of soils 1 Succession of soils a b c Pioneer soils azonal new soils Intrazonal successional soil in development Zonal pedoclimax soil formed under a climax vegetation which develop together 2 Processes of soil profile formation a b c d e Soil Profile Horizons Weathering Leaching climate and relief and elevation Humus production complex organic component Leads to profile development Time speed of pedogenesis varies usually faster in tropical and moist areas and slower in arctic and dry areas see diagrams Fig 41 and P 41 l 0 layer litter layer a 1 unconsolidated litter loose on surface b 02 matted litter being consolidated c Animals are very important especially earthworms and arthropods d Decomposers bacterial and fungi with the mechanical action of animals transform the litter into the humus of the soil e Decomposition is so rapid in tropical soils that the litter layer is normally thin in contrast with the thick litter of cool temperate areas 2 A layer Top Soil Eluvial Zone or horizon of leaching and humus formation and accumulation b A1 Zone of maximum humus accumulation A2 Light zone of maximum leaching Sometimes as in Smiths called the E level for leaching but leaching occurs throughout the A level D Types of l 2 3 E Texture of soil based on particle size 4 5 B Horizon illuvial Zone of deposition where there are depositions of clay iron and aluminum oxides and sometimes calcium carbonate C Horizon Zone of physical weathering of the rocks Erosion progressively destroys the soil when plants are eliminated as in agriculture stripping it down to the C zone or even to the rocks This enhances desertification especially in semiarid areas Time for soil development a Very long time 2000 to 20000 yrs to develop a climax soil especially in temperate areas b Immature soils are azonal gtintrazonal gtzonal c Erosion sets it back to earlier levels litter are biologically important Table 49 Mor litter a Acid small leaves conifers and heaths often b Evergreen b Tight compacted litter thin layer c Decomposes slowly fungi few bacteria e Sharp demarcation from mineral soils f Little humus in soil proper g Few soil animals Enchytraeid earth worms Mull litter Deciduous tree liter Less acid neutral Bacteria abundant Gradual transition into soil Larger pore spaces of mull litter provided ows a richer soil fauna Moder litter Oak leaves are very acid because of tannins thus slow to decompose few bacteria much fungi thus moder is a thick litter layer and is between Mor and Mull litters in characteristics leaf full DQOU39S U related to parent rock or source material see soil triangle P 41 in class notes Use sieves to sort out particle sizes in soil Clay less than 0002 mm colloidal any particles Silt 0002 to 002 mm feels like flour alluvial soils as clay is slow to settle out Fine sand 002 to 02 mm Visible to the eye gritty to the touch Coarse sand 02 to 2mm grains Gravel more than 2mm So you can throw it cannot feel can see individual F Structure Based on relationship among particles and humus l Aggregates called peds are formed Fig 43 in Smiths illustrates some types of peds 2 Peds may be granular crumb like blocky Important is pore space and permeability porous or nonporous sticky or clayey 3 The structure is strongly influenced by humus present which also promotes water and nutrient retention by the soil III Water amp Nutrients A Soil Moisture Cool England is moist with 20 while hot Texas is arid with 30 pattern of rain over the year important with rain in cool period more significant 1 Gravitation water goes to water table leaching occurs along way which depends on solubility of soil nutrients in soil 2 Combined water This is unavailable water chemically bonded with minerals 3 Hygroscopic water This water attached to surface of mineral particles by hydrogen bonding and which is unavailable to plants The smaller the soil particle the greater the hygroscopic water content 4 Capillary water is that available to plants Available field capacity39is the amount of capillary water held by the soil Must subtract the hygroscopic water from the total water in the soil 5 Pore spaces in the soil important as plant roots and animals need air This air is usually saturated with water vapor hence the terrestrial half way house for many small animals fungi protozoa and microbes 6 Temporary pools and wetlands are poorly drained full of water hence lacking in air which kills plants not specially adapted for such wetland conditions 7 Topography and drainage important If water runs off too fast not only is water lost on steep slopes but erosion can readily occur denuding the soil Such slopes should not be farmed but it is a sad sight to see such slopes put to the plow and the soil being washed away This is shortsighted exploitative farming especially prevalent in the tropics B Soils and water holding capacity 1 Sandy soil holds 10 15 its weight in water This is all available or capillary water 2 Clay holds 50 70 its weight in water but much is hygroscopic and not available to plant roots 3 Silt is intermediate and is characteristics of flood plains as silt settles out when the stream overflows while clay continues on down stream to settle out in the ocean or worst behind dams It is better than sand or clay for agriculture hence the agriculture along the Big Brazos River as compared to here in Bryan College Station 4 Loam is the best soil 13 clay 13 silt 13 sand as it combines the best of each particle size 5 Humus The organic fraction can hold loo200 of its weight in water forest soils being rich in humus and roots hold twice as much water as crop lands thus crop lands prone to desertification More over the humus is rapidly destroyed by agriculture 6 Comparison of water holding capacity Clay Loam Silt Sand Wet water 284 217 161 32 Wilting 130 103 75 05 7 Humus is easily destroyed eroded and oxidized away With that the soil structure is lost water holding capacity39and fertility39of the soil is reduced or lost 8 Historical trend of man s influence is to transform marginal areas into deserts Look at North Africa the Near East and now in the Western USA including West Texas Why this desertification C Role of plants in water retention 1 Plants promote uptake of water by soil and decrease runoff of water into streams and moderates flooding 2 Diminishes erosion and excessive leaching of nutrients 3 Prevents baking of soil surface by the sun and raises relative humidity still air in forest diminishes evaporation 4 Promotes return of water into atmosphere by evapotranspiration Hectare 2 12 acre of forest releases 25000 litersday into the atmosphere 5 This in turn promotes the hydrological cycle 6 This is why a forest tends to maintain itself during times of water stress which in agriculture tends to promote disastrous desertification and erosion D Plant adaptations to drought remember crassulacean acid metabolism Xerophytes like mesophytes and hydrophytes cannot handle 70 dehydration of plant cell yet must transpire to obtain water and nutrients and acquire C02 E 2 as Soil 1 N OJ as present on micelles 01 Storage plants Succulents cacti euphorbia Deep roots Mesquite was found going 175 for water Sclerophylls waxy evaporation Deciduous leaves dormant in the dry seasonal forest to conserve water Physiological drought occurs in the winter because the plant roods can t l cutinized leaves to reduce obtain water adequately from cold s01 Ephemerals have seeds that avoid cold and drought to sprout during good conditions the desert may bloom after a rain It is amazing how Fertility Clay and humus link together to form micelles that in neutral soils are negatively charged to create a chemical soil skeleton This holds nutrients Inorganic salts ionize NH4 K Ca Mg H attracted to micelles in forms that plants can absorb Sandy soils hold fertilizers poorly as the nutrients are lost by leaching because clay is absent Leaching occurs naturally because rain carries HZCO3 which exchanges H ions for K Mg Ca NH4 that are then lost and move down in soil to B or C horizon Severely acid rain as is occurring because of SO2 and NOZair pollution makes this much worst especially in areas with already acid soils as in coniferous forests Base saturation content are available nutrients which is highest in neutral soils When hydrogen ions saturate the micelles in acid soils there are no bases available as hydrogen replaces the other bases Under pH 3 4 conditions the soil is very poor Moreover in such acid conditions aluminum is released which creates aluminum toxicity Moreover high acidity also promotes humus breakdown at pH 33 or less In arid climates as there is less leaching the soils may be base saturated by carbonates CaCOQ pH 8 or at pH 10 by Naglk These are very basic soils Thus such soils are at first rich in nutrients under irrigation but salting of the soil by evaporation releases the nutrients quickly and the soils become poor 9 Nutrients available cation exchange capacity H Al Ca Mg K Na39 H has the greatest affinity Adding CaCOBdrives it to neutrality as farmers say sweetens the soil 10 Also since clay amp humus form colloidal micelles a The micelles flocculate at around pH 7 which is best for the soil b Under acidic conditions the micelles deflocculate and H20 moves the humus downward in the soil which loses its beneficial structure c Nutrients are accordingly lost under acidic conditions 11 In the tropics humus is quickly decomposed Since photosynthesis and respiration are at balance at about 80 F cutting the forest accelerates the rate of humus decomposition following the rule of Q102 IV Soil Community A Very Rich diversity of life in the soil 1 Many phyla restricted to the moist protection of high humidity in the soil because they are not well adapted to live in the air medium of the terrestrial biotope Mull litter is the richest in life because of beneficial soil structure mor litter is the poorest 3 The detritus food chain is basic here as most energy in the forest is processed in the soil Unusual and important are the fungi especially the Ascomycetes and Basidiomycetes true fungi which are essentially restricted to the terrestrial environment where they are important in digesting cellulose N as B Fractions of the soil by weight See P 42a in class notes C Percentage by numbers shows the dominance of the microbes Take one square foot of good forest soil There would be 1 100 billion organisms of which only 2 0000004 are the visible organisms the animals which as they are hidden in the soil are often called the Cryptozoa 3 60 bacteria very diverse most poorly known 4 30 Fungi yeasts and relatives also poorly known 5 5 9 Protozoans and algae a rich biota 6 005 True fungi macrofungi that have hyphae forming a mycelium Ascomycetes and Basidomycetes Many of these fungi are mycorrhizae on roots of trees D By size 1 Microbiota by compound microscope algae fungi protozoans Protista use a microscope to study 2 Mesobiota Use a dissecting microscope to study These are easily collected and separated using a Berlese funnel for air forms and a Baermann funnel for water fractions forms See pg 735 in Smiths a Nematodes most feed on bacteria some on algae and plant roots millionsma These are in the water fraction of the soil b Enchytraeid earthworms that are small and white c Microarthropods Soil mites Acarina and springtails Collembola thousandsm3 and small insects hundredsm5 These are in air fraction of the soil 3 Macrobiota that can be collected by hand plant roots large fungi large earthworms Lumbricidae larger insects diplopods chilopods sowbugs gophers mice and moles a Macrobiota most important in mechanically turning over the soil and in crumbling wood bMacrobiota assimilate only 5 10 of leaf weight but their activities promotes microbial activities that breaks down cellulose as we saw in the discussing the detritus food chains Soil Classification A Dokuyachev and many others used the idea of soil development and zonal soils in reference to climate as a basis for classification of soils This is the terminology used throughout the world except in the USA 1 Each individual soil is a pedon Pedons are grouped 2 Series gtCatenas gt Families gt Subgroups gtGreat groups gt Suborders gt Orders Can also group catenas into functional groups based on topography toposequences vegetation biosequences and time chronosequences 3 Name of a series is based on a type soil and locality very much like that used in taxonomy B Classification of USDA soil science See Fig 43 in Smiths Smiths in the 6m edition leave out the old ordinal classification I give it in your class notes on P 42 which shows the relationship of soils to climate 1 The USDA system is based on soil structure less on development of the soil and the effect of climate 2 New nomenclature based on soil characteristics and uses unusual suffixes for naming soils 3 Actually it is little used outside of USA by other soil scientists and ecologists VI Soils vegetation and climate see diagrams P 42 Your textbook covers this poorly as the biomes are in a different part of the textbook climates in another A Behavior of clay under different climates is important 1 Granite breaks down into quartz mica an feldspars 2 Clay minerals are breakdown products of Feldspars and Micas Summary equation of clays including some K and Mg oxides is as follows 3 Ca Mg K metal X A1203 Y Fe203 Z Si02 nH2O Example is orthoclase feldspar K20 A1203 68i02 gt K2C03 A1203 Si02 2H2O Kaolinite white clay Bauxite is c1ay that is used for aluminum ore 4 Clays further breakdown into silica SiOQ and the sesquioxides A1203 and Fe203 a Under cold conditions Sesquioxides are mobile leach into B horizon silica stays in A horizon conifers promote acid conditions promote Classic podzolization of the taiga b Hot tropical conditions silica mobile leaches down into the B horizon while sesquioxides remain in the A horizon classical laterization If moist hydrated A1203xH20 Fe203xH combine with humus and remains a colloid which holds nutrients and maintains friable soil If the soil dries and the humus burns off it turns into a brick unusable for agriculture B Soils of dry and climatic areas Precipitation is less than Evaporation Gives rise to Pedocal Soils of arid areas as compared to Pedalfers of humid areas 1 Calcification Mollisols as in blackland prairies a Too dry to leach Ca and other divalents from soil only upper horizons are affected b High base saturation neutral to basic lots of nutrients present a rich soil c CaC03 is moved to B horizon or even C horizon d Chernozem soils deep black soils deep B horizon blackland prairies of Texas e Go to steppes drier climates then Chestnut and Brown pedocal soils occur It s dangerous to irrigate such soils because of the danger of evaporative salinization It s happening now in West Texas f Because the grasses die back every year and decomposition is slow the humus accumulates in the soil a process called melanization This makes for an excellent soil however in dry years which is a normal event in semiarid areas breaking the sod for agriculture allows the wind to blow the soil away creating the dust bowl conditions famous in the 1930s and a serious threat with global warming 2 Aridosols Sierozems the pale soils of deserts a Gray desert soils cold deserts b Desert soils yellow nonhumus desert soil c Red desert soil oxidation occurs in tropics d Salinization white crust of salts alkali and salt soils extremely salty when dried Irrigation promotes this condition creating new salt deserts e Because the plants can t hold the soil a desert surface pavement develops made of small stones C Pedalfer Soils l Gleization Tundra soils blue gray soils a C Horizon is permafrost no leaching b Acid peat in A zone muskegs and fellfields c B horizon is Blue Gray due to reduced Fe poor aeration because of the permafrost 2 Podzolization Promoted by cold Classic Podzols or Spodosols of the Taiga Named after the ash white layer in the A horizon Tend to be young soils because of recent glaciation and cold conditions b Clay breaks down sesquioxides mobile to B horizon silicates immobile stay in A horizon c Classic Podzols in Taiga White layer of silica in A2 iron oxide in B Grey surface soils d Mor litter of conifers acid slow decomposition poor integration of humus in taiga and conifers clay humus micelles weak little nutrients retention because of H domination acid rain affects this greatly as colloids deflocculate under high acidity acid conditions least solubility of silica Aluminum toxicity common danger e Mull litter of deciduous forests is less acid more basic Brown Podzol soils of the northern United States and Europe good integration of humus better clay humus micelles better nutrient levels More resistance to nutrient loss reasonably good for agriculture f Acidity high base replacement poor soil in classical podzols of Taiga 3 Laterization latosols a Promoted by heat deep soils of tropics derived from bedrock b Clay sesquioxides immobile silicates mobile red soils c Warm shade 80 F Decomposition roughly equals photosynthesis Clay humus micelles are maintained for nutrient conservation aided by mycorrhizae d However cut the forest down the exposure to the sun temperature increase to about lOO F then decomposition increases humus decreases e Clay Sesquioxides in A horizon proceed to bake into a brick like laterite f Bauxite is soil high in aluminum source of aluminum strip mining the soil g Tropical soils are very vulnerable together with short photoperiods poor for agriculture Tropical Forests should be left alone the forest promotes good watersheds and helps prevent desertification i The exceptions are alluvial soils along rivers and some unusual volcanic soils as in Java 4 Warm temperate areas have lateritic podzols a Podzolization occurs in the winter While b Laterization occurs in the summer thus the red color of southern soils 339 c Prairie Podzols Brunizems Have lots of Ca and are pedalfers by climate but grasses promote calcium especially in limestone areas d Soils good for agriculture as neither podzolization nor laterization is extreme