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towson niche

towson niche


School: Towson University
Department: Biology
Course: Intro to Ecology and Evolution
Professor: L johnson
Term: Spring 2015
Tags: Biology: Ecology and Evolution
Cost: 50
Name: biol 202 ex4 guide with just question on first few pages and answers following
Description: species interaction to trophic levels
Uploaded: 04/24/2017
24 Pages 207 Views 0 Unlocks

In nature, what type of soil is Galium saxatile found on?

What are the potential outcomes of competition amongst species?

What is a community?

What is a community? Distinguish between interspecific and intraspecific competition. What are the potential outcomes of competition amongst species? In nature, what type of soil is Galium saxatile found on? What type of soil is Galium sylvestre  found on? Why?  Describe the growth of P. aurelia and P. caudatum when theyIf you want to learn more check out uconn pnb
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grew alone and when they grew  together. Why does this study provide evidence for the competitive exclusion principle? When can barnacles disperse? When are they sessile? What is a limiting resource for barnacles? What is exploitative competition? What is interference competition? Distinguish between realized and fundamental niches. What is allelopathy? The black walnut tree produces juglone, which inhibits enzymes in other plants. Why is this an  example of allelopathy and interference competition? How do the eucalyptus trees exhibit interference competition? What does the Pisaster sea star prey on? What happened when Robert Paine removed sea stars from his experimental treatment? What is a keystone predator? How can competition result in resource partitioning and character displacement? Describe  examples. Describe plant adaptations to defend against herbivores. Describe coevolution between the mustard family and cabbage butterfly caterpillars. Describe adaptations that allow animals to defend against predators. Distinguish between Batesian and Mullerian mimicry. How can population growth be regulated from both above and below? Plots of strawberry plants were exposed to one of two treatments. The control treatment  included just the Cyclamen mites, while the experimental treatment included Cyclamen mites  and the predatory Typhlodromus mites. Describe the results of this study. Describe the consumer/resource relationship between Chrysolina and the Klamath weed. When predators influence the regulation of prey populations, what are the two possible  outcomes? Describe the stages in a predator prey cycle. How did Charles Elton use data from Hudson’s Bay fur company to estimate hare and lynx  population numbers? Describe Huffaker’s first experimental design that featured predatory Typhlodromus accidentalis and the six-spotted mite prey. How did Huffaker increase the environmental variation in his second experimental design?  What was the outcome? What stabilizing factors reduce predator-prey cycles? What is commensalism? Describe examples. Why is parasitism considered a +/- interaction while mutualism is a +/+ interaction? What is a parasite? What is a host? Define “ecto-parasite”. Provide examples. Define “endo-parasite”. Provide examples. How did parasite flukes influence the surfacing and jerking behavior of killifish?  How do flatworms influence the behavior of ants? Why it is important for the Schistosomes to produce a large number of eggs? What is a vector? Name examples of vectors. What is molecular mimicry? How does it help the parasite to escape the immune response of the  host? What is antigenic variation? How does it help the parasite evade the host immune system? Describe the adaptations of hosts against parasitic infections.Why do the introduced parasites cause mass mortality in their hosts?  How do the parasites control host populations in a density-dependent manner? Define mutualism. Provide an example of mutualism. What is symbiotic mutualism? What is non-symbiotic mutualism? Define trophic mutualism, defense mutualism and dispersive mutualism. Reference examples.Exam 4 Ch. 56.1­5, 57.2­3  Species interactions 1. What is a community? populations of multiple species interacting in a given area ­Communities can be categorized by their species or by their properties (spec richness or  primary productivity) 2. Distinguish between interspecific and intraspecific competition.  Intraspecific: competition between same species - Using up resources - Density­dependent regulation Interspecific competition: competition between different species  3. What are the potential outcomes of competition amongst species? 1) Competitive Exclusion (exclusion of a species from a locality­ influences range)  - Competitive Exclusion Principle: two species competing for limiting resources  (housing, food, etc.) but species that uses resource most efficiently will eliminate  the other - Reduction in niche occupancy  - No 2 spec with the same niche can co­exist indefinitely when resources are limiting 2) Resource partitioning and character displacement  - species evolved differences that reduce competition 4. In nature, what type of soil is Galium saxatile found on? What type of soil is Galium  sylvestre found on? Why? Galium Sylvestre on alkaline soils. Galium saxatile on acidic  soils. Each on the soil they use resources more efficiently on competitive exclusion resulted in the different ranges - when planted separately in both types of soil ­ both survived - when planted together ­ one species outcompeted the other - 2 habitats resulted in competitive exclusion 5. Describe the growth of P. aurelia and P. caudatum when they grew alone and when they  grew together. Why does this study provide evidence for the competitive exclusion  principle? when grown together, one excludes the other. Because P. aurelia eliminates P.  caudatum (the less rigorous competitor). p.aurelia grows faster because it better utilizes its  resources Each grew fine in the medium when aloneWhen another species grew with p.caudatum, they both survived because caudatum fed on  bacteria in the high oxygen part of tube and the other spec fed on yeast in the lower oxygen  part of the tube. The fundamental niche of each spec was the whole culture tube - When they were grown without a competitor, both spec reached densities 3x greater  6. When can barnacles disperse? When are they sessile? (and how competition results in reduction in niche occupancy) Barnacles can disperse and move around well in larval form but when they mature,  they submerge themselves on rocks and can’t move around 7. What is a limiting resource for barnacles?. Thalamus could survive in upper and lower  intertitle zone but balanus can only survive lower intertitle zone (both the fundamental and  realized niche are the lower intertitle zone). balanus struggled with desiccation (dryness) in  the upper intertitle zone and thalmus did well if it didn’t compete with the other species ­  balanus live in lower intertitle zone (deeper water) and thalamus live in upper intertitle  zone (shallow water) ­ when removed balanus off rocks, thalamus extended range to deeper water. Balanus is a  better competitor because it grows beneath thalamus and pops it off the rock (interference competition)  ­ when removed thalamus, balanus still couldn’t survive shallow water because its not  adapted to desiccation. Fundamental niche of thalamus includes both shallow and deeper  zones but its realized niche is narrower because can be outcompeted in parts of its  fundamental niche 8. What is exploitative competition? What is interference competition? Exploitative competition: Spec using resources more efficiently than other  species Interference competition: aggressive interactions (punching, biting, chemical  warfare (allelopathy),etc) ­ Chipmunks do this 9. Distinguish between realized and fundamental niches. Fundamental niche: what a spec is capable of using based on tolerance limits  and resource needs ­ range of physical and chemical conditions under which the spec can persist in the absence of competitors ­ potential to live Realized niche: actual set of environmental conditions when interacting with  other species (ie. including the presence/absence of other spec), in which the  spec can establish a stable pop ­ realized niche usually smaller than its fundamental niche because interspecific  interactions limit a spec use of some resources ­ sometimes the absence of another spec causes a smaller realized niche (if insects leave  the habitat and stop pollinating the plants, the realized niche of the plant spec may  decrease) ­ what happens in reality ­ portion of the fundamental niche that the spec uses as a result of interacting with the other species  10. What is allelopathy? plants release toxins into the environment to inhibit the growth of the  surrounding plants (their competition) 11. The black walnut tree produces juglone, which inhibits enzymes in other plants. Why is  this an example of allelopathy and interference competition? Because only few species  can tolerate the juglone and grow under the tree Apparent competition: predator (consumer) species mediates competition between two or  more species  12. How do the eucalyptus trees exhibit interference competition? Eucalyptus releases an oil  that catches fire easily (fire destroys seedlings of competitors) ­ Eucalyptus resilient to fire and survives to reproduces itself 13.What does the Pisaster sea star prey on? mussels, barnacles, mollusks, limpets 14. What happened when Robert Paine removed sea stars from his experimental treatment? species diversity within community decreased. Mussel population increased and  outcompeted the other species in the community, driving them locally extinct 15. What is a keystone predator? responsible for increasing diversity in the community ­ Predation reduces competition in natural communities ­ pisaster fish present= diversity in the community 16. How can competition result in resource partitioning and character displacement?  Describe examples. Character displacement: differences among similar species whose  distributions overlap geographically are accentuated in regions where the  species co-occurResource part: subdividing niche to avoid competition  ­ Often seen in similar spec that occupy the same area (sympatric spec).  they usually live in dif portions of habitat or eat dif food. Probably a result  of nat selec causing similar spec to diverge in resource use Anole lizard: species evolved to live and prey in grasses, others use the trunk,  crown, or branches of the tree (ie. Resource partitioning). The character  displacement is the difference in leg/tail size Darwins Finch: when they live in different islands, they have similar beak sizes  and eat similar things. when found in sympatry, there’s a shift in beak size  because they evolve to specialize in different seeds and reduce competition  between species 17. Describe plant adaptations to defend against herbivores. plants release toxins or disturb  the metabolism of herbivores ­ Mustard family produces mustard oils (distasteful and toxic to insects) to reduce  likelihood of being eaten ­ Milkweed produces milky saps (disrupts heart function in insects) 18. Describe coevolution between the mustard family and cabbage butterfly caterpillars.  Cabbage butterfly caterpillars have evolved to break down the mustard oils and now have a food source just for themselves 19. Describe adaptations that allow animals to defend against predators. ­ Chemical defenses (poison draft frog evolved toxicity and color as a warning) ­ Defensive coloration (camouflage­ waved umber looks like a twig) ­ Mimicry 20. Distinguish between Batesian and Mullerian mimicry. Batesian mimicry: species without chemical defenses that mimic a  toxic/distasteful species (tiger swallowtail butterfly that looks like the toxic  pipeline butterfly)  ­ palpable species (swallowtail) mimics warming coloration of toxic spec. benefit: less  likely to be eaten Mullerian mimicry: distasteful/toxic species look alike to increase survival ­ If all are dangerous or poisonous and look alike, predators will quickly learn to avoid  ­ If predator tries one and has bad experience, will avoid all similar How can population growth be regulated from both above and below? predator eats prey ­ Cow eats grass ­ wolf eats cow - Cow is both consumer and resource. consumer when eats grass, resource when gets eaten 21. Plots of strawberry plants were exposed to one of two treatments. The control treatment  included just the Cyclamen mites, while the experimental treatment included Cyclamen  mites and the predatory Typhlodromus mites. Describe the results of this study. Example of how a consumer regulates its resource population Cyclamen mites feed on strawberry fields. They will decimate the fields - Typhlodromus mites (predator) usually follow and feed on the Cyclamen mites Control plot: both cycl and tro live normally (Cyclamen mite population numbers are low but stable) Exp plot- typhl couldn’t invade, it was just cyclamen -if take predator out, have intense increases and decreases in pop size -Cycl mite present more than in control plot Describe the consumer/resource relationship between Chrysolina and  the Klamath weed. Klamath weed is detrimental so Chrysolina beetle was  introduced - Consumer regulating the resource pop 22. When predators influence the regulation of prey populations, what are the two possible  outcomes? 1) Pop goes extinct - Sometimes follwed by predator pop going extinct 2) Predator/prey population cycles 23. Describe the stages in a predator prey cycle. - See increase in prey (hare in blue) followed in increase in predator (lynx) pop and then  prey crashing followed by predator population crashing when prey increase, predator increases then prey crashes and predator also crashes 24. How did Charles Elton use data from Hudson’s Bay fur company to estimate hare and  lynx population numbers? - Scientist assumed number of furs mimicked pop size - a­when plotted data he found good evidence. See increase in prey (hare) followed by in  increase in predator (lynx) pop and then prey crashing as predator crashedEnvironmental stability matters when things go extinct and… Scitist studied oranges and mites Predator is typhlodromus occid and prey­mite Predator has to walk, prey can float He set up environ of universes (oranges). Wanted t create predator­prey cycles Prdatros ate everyone and every1 died when set everyone loose. He then added variability (wraped oranges in paper so mites can hide).everyone still died but it took longer so he  knows variability associated with time everyone goes extince. Last expt he put vaselin  between oranges to slow down walking mites and added wooden pegs on oranges so  mites can climb up and jump between oranges­this created head start for prey and slowed down preadtors, instead of ever1 dieing he got oreadto­prey pop cycles. 25. Describe Huffaker’s first experimental design that featured predatory Typhlodromus  accidentalis and the six­spotted mite prey. - Environmental stability matters when things go extinct and… - Scientist studied oranges and mites - Predator= typhlodromus accid, prey=mite - Predator has to walk, prey can float - He set up environ of universes (oranges). Wanted to create predator­prey cycles - Predators ate everyone and every1 died when set everyone loose. He then added  variability (wrapped oranges in paper so mites can hide).everyone still died but it took  longer so he knows variability associated with time everyone goes extince.  26. How did Huffaker increase the environmental variation in his second experimental  design? What was the outcome? - Last expt he put Vaseline between oranges to slow down walking mites and added  wooden pegs on oranges so mites can climb up and jump between oranges­this created  head start for prey and slowed down predators, instead of ever1 dying he got pred­prey  pop cycles. - Environmental variation increased the likelihood of predator­prey cycles 27. What stabilizing factors reduce predator­prey cycles? 1.Predator inefficiency -slowing down predator increases liklihood if stable pop cycles instead of predator  prey 2. density-depend limitation.. 3. refuges for the prey at low densities4. Reduced time delays in predator responses to changes in prey abundance 5. alternative food source… Over last decade common raven pop increased because access to anthropogenic  food reources Spec interactions: Any competition is going to decrease resources so ita a neg-neg interaction Parasitism is a +/- interaction Symbiosis/mutalism is a plus-plus because the interaction between.. Commensalism is a plus/zero interact 28. What is commensalism? Describe examples. Commensalism occurs when one spec pos effected and other spec not effected at  all - Ex. Spanish moth doesn’t have a negative effect to hang on to trees, doesn’t affect tree  but benefits from sunlight access. - Ex. Barnacles attach to whale, good for barnacles to move and doesn’t affect whales - We thought Oxpecker bird feeds on invertebrates that live on herbivores (lice on deer).  Good for bird and good for the deer. But it depends on coditions. When drought occurs,  the birds will pull open their scalps and drink their blood, turning into parasitism rather  than commensalism  29. Why is parasitism considered a +/­ interaction while mutualism is a +/+ interaction? Mutualism: both spec benefit Parasitism: one spec benefits and the other is harmed - Obtain nutrients from other living organisms (hosts) - Invades bodies of hosts and on partially digested food, tissues (blood) etc o Decreases fitness of host o Parasites generally don’t kill hosts o Long term, close associations 30. What is a parasite? Something that feeds off of you and benefits but harms what it benefits  form  What is a host? What the parasite lives in 31. Define “ecto­parasite”. Provide examples. Parasites that feed on an external surface of an  organism ­> lice, ticks- Cascuta (plant) is heterotrophic (unable to produce its own food), it obtains food from host  plants it grows on  32. Define “endo­parasite”. Provide examples. Parasites that live within the body of their host Endoparasite examples: Plasmodium induces malaria  Tapeworm feeds off your lunch Brainworm parasites (parasites have complex life cycles) mature in the brain of  deer. They produce eggs that hatch into larvae, the larvae passes through  bloodstream to lungs,coughed up and swallowed, leaves deer body through feces,  snails become infected following contact with feces, larvae develop/grow in snails,  deer become infected by eating grass/snails, larvae penetrate the deer stomach  and travel to the brain through the spinal cord Adaptations of parasites: 1. Transmission adaptations - Massive reproductive output (reproduce a lot) - Use of vectors (plasmodium is a protest induces malaria and a vector is important to help  transmission. Seed eating birds another ex - Host behavior manipulation 2. Adaptations to establish within host - Have to make it to the host and not get flushed out 33.How did parasite flukes influence the surfacing and jerking  behavior of killifish? Increase in number of parasite flukes is correlated with increased surfacing/jerking…  increases the likelihood of transmission to next host (review figures in power point slides) 34. How do flatworms influence the behavior of ants? They infect the ant by entering their  brain and forcing them to climb the tree blade and lock their mandible to be transmitted to  the herbivore that eats it 35. Why it is important for the Schistosomes to produce a large number of eggs? Increases  likelihood that one will get transmitted to host (Transmission adaptation: mass reproductive output) 36. What is a vector? Name examples of vectors. Vectors helps with transmission of parasites  between hosts - mosquitos are important for transmitting the parasite between hosts- Seed­eating birds move mistletoes (parasite) between hosts. Parasite uses trees nutrients 37. What is molecular mimicry? How does it help the parasite to escape the immune response of the host? Parasites coat themselves in the host’s blood ­> host’s immune system does not  recognize parasite as non­self 38. What is antigenic variation? How does it help the parasite evade the host immune  system? Parasite shifts antigens to confuse host’s immune system 39. Describe the adaptations of HOSTS against parasitic infections. Parasites must make it to  host without getting attacked by Immune system Adaptations of parasites: Transmission adaptations Massive reproductive output (reproduce a lot) Use of vectors (plasmodium is a protest induces malaria and a vector is important to help  transmission. Seed eating birds another ex Host behavior manipulation Adaptations to establish within host Have to make it to the host and not get flushed out 40. Why do the introduced parasites cause mass mortality in their hosts? Newly introduced  parasites can drastically reduce host population when hosts have not been exposed to the  parasite before because the host didn’t evolve defenses yet - Avian malaria introduced by mosquitos has eliminated most low elevation native bird  populations in hawii 41. How do the parasites control host populations in a density­dependent manner? When  parasites are transmitted through the contact of hosts and the parasites are endemic - When host population density is high, crowding can increase the parasite transmission rate 42. Define mutualism. Provide an example of mutualism. Both spec benefit. - characteristics of flowers evolved in relation to characteristics of the animals that visited  them for food and spread the pollen from plant to plant. At the same time characteristics of  animals changed, increasing their specialization for obtaining food or other substances from  flowers.  - Aphids suck fluid from plant, extract nutrients, and excrete it. Ants eat the excretion. Ants  domesticated the aphids. - Acacia tree has leaflet with nectar that feeds ants. The ants provide plants with nutrients and  protect from herbivores (attach) and shading of other plants (by cutting touching branches  and allowing light in)43. What is symbiotic mutualism? two spec involved are closely related and At least one species  is dependent on the other - Reef forming corals and photosynthetic algae (zooxanthellae): coral provides zoox. with a  protected environment, zoox. Provides 90% of the daily energy requirement of the corals  through photosynthesis. corals cannot survive without zoox. What is non­symbiotic mutualism? Two involved spec not dependent on each other - Flowering plants and seed disperses benefit from one another but are not dependent on one  another 44.  trophic mutualism: are specialized to obtain energy and nutrients - Legumes and nitrogen fixing bacteria - Bacteria of genus Rhizobium have the ability to use nitrogen gas and cnvert it to a chemically usable form (Nitrogen fixation) - These nitrogen fixing rhizobium bacteria inhabit the root nodules of legumes such as beans,  clover and peas - Bacteria receive carbon and other nutrients from the plant  defense mutualism: defending the partner in exchange for food or shelter - Acacia trees provide large thorns as nests for ants - Trees also produce Beltian bodies/secretions which provide food for ants. Ants only live  within these thorns - Ants protect trees from herbivorous insects. They also prune plants around the Acacia  making sure the tree has abundant light dispersive mutualism: transport of seed and pollen - These interactions include plant­pollinator interactions and plant­seed disperser interactions What is a climax community? steady state which occurs under a particular set  of environmental conditions. Series of states within the community that progresses  towards a stable state 45. What is the sequence of changes (succession) in abandoned agricultural fields? Succession: stable area but changing community (stable climate but comm changes) - Happens because spec alter habitat and resources available in it in ways that favor other spec Primary succession: organisms move into lifeless area and change it (in lake after glacier  retreat, volcanic islands that rise from sea)  Secondary succession: disturbed area eventually recover (cleared or burned wooded area  slowly recover because life remained) Succession in agricultural fields in North Carolina ­ Tracking of succession following the abandonment of agricultural fields ­ Farmers went in and cleared the land and planted crops, eventually ran the soil into the  ground­ sucked all the nutrients from ground from farming and left the field behind­ get weeds in abandoned agricultural fields (horseweed/crabgrass), followed by shrubs,  followed by pine trees (first tree species that colonized areas), followed by hardwood  trees (maple, oak, hemlock) Start with newly formed or disturbed habitat. next, pioneer (early successional)  species colonize that habitat Pioneer species can survive in a poor environment (low on resources, very  disturbed, etc.) ­ Eventually they are replaced by better competitors, which results in the climax  community Succession occurs, go from initial disturbed state or stat that’s devoid of life, have  community succession across time and then we get a climax community (final state  after which there is no more succession) ­ Not every community ends in a climax­steady state after succession occurs 46. What is the sequence of changes (succession) in sand dunes? Early successional spec (mirum and bluestem grass) establish themselves near a  sand dune, followed by shrubs, then pines, then hardwood. The pine competitors  are replaced by hardwood trees (the climax community) 47. What is the definition of primary succession? Of secondary succession? Primary succession: development of community in new habitat that is devoid  (lacking) of life ­ sand dune succession (the sand has no life to start with) ­ volcanic explosion resulted in lava covering the area (nothing living left) ­ Kettle ponds in Canada with a boreal climate boreal climate: barrier between temperate and arctic climate ­ Cold winters and short mild summers Kettle ponds: holes in ground from glaciers moving  Bog succession: establishment of aquatic plants around the ponds ­ Sedges (aquatic plants) form atop ponds. Sedges eventually die and deposit detritus  (organic matter) into ponds­ Detritus fills the ponds and the pond disappears ­ Following establishment of aquatic plants and sedges, come shrubs and mosses. ­ Spruce, birch, maples establish around ponds As detritus fills ponds, they become terrestrial habitat (how ponds transition through succession to wet terrestrial environment than a pond)  Secondary succession: regeneration of a community following a disturbance with  some life present ­ agricultural fields succession (abandoned fields were disturbed but have some soybean  plant or some other life left) ­ blowout in seagrass community (storm wipes out aquatic plants in area of ocean) rhizophytic macroalgae (early succession spec) establishes itself following a blowout ­ they help stabilize sand ­ an environment with sand is a shifting substrate (help stabilize the environment and make it more habitable for later successional spec) ­ rhizophytic macroalgae is followed by  sholl and turtle grass  ­ early successional spec responsible for stabilizing sand and depositing their bodies in the  sand (when they die) to make the area hospitable for subsequent spec colinizations 48. How was primary succession initiated on Krakatau island? volcanic explosion resulted in lava covering the area (nothing living left) 49. Describe primary succession on Krakatau island. 9 months after explosion, there was a  single spider and slowly plants and animals showed and filled the land. There was no life after  explosion but experienced rapid successional change as vegetation was reestablished. Few  b;ades of grass appeared the next yr and within 15 yr, vegetation was well established and  interior was covered with dense grasslands. By 1930 was almost entirely forested. 50. Why do early­successional species benefit from being shade intolerant and fast growing? Early successional spec have many small seeds, disperse by wind or by sticking to  fur, have rapid growth and low tolerance for shade (like sunlight)… early successional species benefit from being shade intolerant because there is lots of  light in recently disturbed areas (no trees) or areas where there has never been life - Benefit from growing faster than the species around you that will produce shade ­ fast or r­selected spec ­ do well when released from competition (lots of resources available) early successional species are shade intolerant and fast growing. why does that  make sense given what we know about the environ?­ When talking about disturbed habitat like recent volcanic interruption, or abandoned  agricultural field, these are areas without shade so they have to be adapted to full  sunlight. In turn, the reason they are adapted to grow faster because as they grow they  create shade for spec growing beneath or around so it benefits to be adapted to full sun  but also to outgrow individuals around so don’t get trapped under their shade  51. Why do late successional species benefit from being shade tolerant and slow growing? Late successional spec have small numbers large seeds and grow slowly and like  shade ­ slow or k­selected spec ­ do well when operating close to caring capacity. Better competitors­ outcompete early  successional spec K-selected spec are always growing from beneath other plants (from under shrubs  that colonized areas around it). These late success spec must be shade intolerant  because always operating with less sunlight. As result they grow slower because  have lower rates of photosynthesis but still continue growing.  52. Why do early successional species benefit from having small seeds? Early successional spec are in disturbed environments that are devoid of  life/recently disturbed and are not hospitable to animals so they have small seeds  that can be dispersed by the wind to get around 53. Why do late­successional species benefit from having large seeds? They produce larger seeds because they are dispersed by animals. Have to be shade  tolerant because grow beneath other plants. Pays to have large seeds with lots of nutrients because lacks sunlight/photosynthesis earlier in life 54. What is establishment? Inhibition? Tolerance? Three categories of interactions 1. Establishment: early successional (r­selected) species can tolerate harsh conditions ­ horseweed 2. Facilitation: processes by which one species increases the probability of a second species  becoming established  ­ moss in glacier bay succession convert nitrogen to a form that allow alders invade ­ nitrogen produced by alders lead to robust spruce forests that protect from insects ­ Early success spec provides shade for later succe spec (they need shade, are not adapted  to full sunlight­horseweed and crabgrass established in area to create shade and facilitates shrubs to grow subsequently) 3. Inhibition: occurs when one species’ fitness is suppressed by the presence of another ­ Hardwoods outcompeting the pines Black walnut tree produces hydroxy juglone which is toxic to other plants around it  (example of inhibition) Over the course of succession, the number of spec typically increases as the  environ becomes more hospitable but sometimes as the ecosystems mature, more  k-selected replace r-selected spec and superior competitors force out other spec,  leading to a decline in spec richness 55. How do alder trees facilitate the establishment of spruce trees? ­ alder trees show up at the same time as pines and are one of the first tree spec that  establish in an area. Good for everyone who follows them because they have nitrogen fixing bacteria in their roots (change chemical composition of nitrogen deficient soils).  Once trees change the composition, other trees can establish and follow. Spruce trees  establish. When spruce trees in nitrogen rich soils, they are better competitors than alder  trees (outcompete) when on nitrogen rich soils. Unfortunately, as soon as spruce come  into an area, they destroy their own chance of survival because they change the soil so  that they cant compete on it 56. How do black walnut trees inhibit the establishment of other plant species? What is the  term for this kind of “chemical warfare”? Black walnut trees produce hydroxy juglone  which inhibits enzymes in other plants. Only few species can grow under this tree Allelopathy 57. How does succession influence the animal species in a community? see succession in animal communities ­ Plant and animal community changed on krakatau island following explosion. Wiped out  life on island. ­ 3yr later there were 24 spec that made their way to island and established. 10 spec were  sea dispersed ­ 1883 was explosion. Initially, All seeds that made it to island were sea or  wind dispersed (early, r ­selected) ­ Later enough tree spec established on island so forest grew attracting animals, bringing  seeds in feces ­ As success occurs, see changes in plants and animal community from single spider to  spec diverse area.  ­ See transition from spec on wind to animal dispersed Read a little more about this in your textbook How does species diversity change with succession? As succession  progresses (yrs after disturbance), see uptick in spec diversity (number of spec  present and if in equal numbers), When start transitioning in later succs. times  (when shrubs start to establish), see fewer spec or diversity. When reach climax community (steady state at end of success. aser) have fewest spec present because have great competitors left Spec diversity- number and abundance of spec present ­ Community has high number and even spec ­ increases when trees enter ­ decreases when reach climax community because everyone left is great at outcompeting  other spec ­ Species diversity is actually lowest when community is at its “climax” state Intermediate Disturbance Hypothesis: Communities experiencing moderate  amounts of disturbance, will have higher levels of species diversity/richness than  communities experiencing either little or great amounts of disturbance Two factors 1. In communities where moderate amounts of disturbance occur, patches of habitat exist at  different successional stages ­ Dif stages cause early/late succession spec to occur in an area, increasing spec richness  and diversity (full range of spec) ­ Patches of area with dif stages succession ex: tree collapses in rainforest, succession in  disturbed area is a early succession stage but environment around it is late succession  (how patchiness contributes to greater spec diversity) 2. Moderate levels of disturbance may prevent communities from reaching the final stages  of succession in which a few dominant competitors eliminate most of the other species ­ Lowest spec diversity when reach climax state and left with best competitors so spec  diversity and richness is lowest ­ enough disturbance that never reach climax state good for diversity and richness  local disturbances affect small areas (tree falls), severe disturbances affect large  area (droubt, flood) 58. How can climax communities vary along an environmental continuum? Different dominant species present depending on precipitation/temperature  conditions 59. What is a transient community? Comes and goes 60. What is a closed community? What is an open community? How do the two differ? Spec distributed independently with respect to one another in an open community. closed communities: distributions of many spec coincide closely and are largely  separated from distribution of other spec open communities: local associations of spec having individuals and partially  overlapping ecological distributions 61. What is an ecotone? From book: Places a community changes abruptly ­ the abundance of spec in a community often changes in a synchronous pattern  from slides: boundaries between closed communities… occur where there is  rapid replacement of species between closed communities ­ regions of rapid replacement of spec along gradient 62. Is the deciduous forest in the eastern United States an open or closed community? 63. What is the continuum concept? One community merges into the next rather than  representing discretely dif spec What is gradient analysis? plotting and interpreting abundances of spec along  an environmental gradient 64. What is species richness? number of spec present in community 65. How does the presence of the Pisaster starfish (a keystone predator) influence species  diversity in the intertidal community? Pisaster fish eat mussels, barnacles, mollusks.  When removed the sea stars, the number of prey decreased. Mussle population increased  and outcompeted the other spec in the community, driving them locally extinct 66. Why does species richness increase with the size of the area being sampled? increases with larger area because more habitats included in sampling scale (forest vs continent) 67. How is abundance and relative abundance measured? Abundance is measured by  number of individuals, density or biomass in a community. relative abundance (pi) is  the proportion of individuals in a community represented by each species 68. Are most species in a community found at low, intermediate or high abundances? Ecosystem with intermediate levels of productivity have greatest numbers of spec 69. What is a rank­abundance curve? plots the relative abundance of each species in a community in rank order from most abundant species to least abundant  species 70. What is species evenness? comparison of the relative abundance of each species in a  communityWhat is the species richness in each community? How does species  evenness compare between communities? Spec richness is how many spec  are present in community. Spec richness is a reflection of spec diversity. spec  evenness is the comparison of the relative abundance of each spec in a community  71. How does one calculate the Simpson’s index? How does one calculate the Shannon Weiner index? How should these values be interpreted? Simpsons: Ranges from 1 to  the total number spec. Max value occurs when all the spec in the community  have equal abundances 1/sum(pi)^2  Pi= # indiv in 1 spec/sum of all indiv.  Shannon: Ranges from 0 to the max value that is ln of specin community . Max  value occurs when all the spec in the community have equal abundances  ­sum(pi)(ln pi)  How does one calculate the Jaccard’s index of similarity? How is this  value interpreted? values range from 0-1 0= no spec in common 1= communities have identical spec number similar spec/ 1 spec +other spec B+ number similar spec values range from 0-1 0= no spec in common 1= communities have identical specWhat is an ecosystem? organisms together  in a physical and chemical envir72. The relationship between primary productivity and species richness is not linear. What  have scientists hypothesized regarding this pattern? low productivity=few herbivores so  superior competitors eliminate most plant species. high productivity=many herbivores and  only plants resistant to grazing survive. greatest numbers of species coexist at intermediate  levels of productivity and herbivory Hyptoh 1: variation in temp allows dif spec to thrive at dif times Could result in greater spec richness Hypoth 2: stable temp conditions support specialized spec that would be unable to  survive where the temp fluctuates and could result in increase spec richness Species richness graph represents hypoth 2 Why do tropics have such high biodiversity? Evolutionary age of tropical region,  invreased productivity, stability/consistency of conditions, predation, spatial  heterogeneity See increased prod because more sunlight? 73. There is a positive relationship between habitat heterogeneity and species richness…  why? Greater habitat heterogeneity = more microhabitats = more niches = more species  capable of surviving in a given area Equilibrium theory of island diversity Colonization begins=rate of colonization decreases Right side= colonization rate=0 because it can colonize the … Left side= ..increases The further the black dots, the more the spec is present How we distinguish colonization and extinction rate 74. What have scientists hypothesized regarding the relationship between climate and species richness? Hypoth 1: variation in temp allows dif spec to thrive at dif times ­ Could result in greater spec richness Hypoth 2: stable temp conditions support specialized spec that would be unable  to survive where conditions fluctuate ­ could result in greater spec richness 75. Species richness is particularly high in the tropics. What are the arguments for this? Why do tropics have such high biodiversity? Evolutionary age of tropical region,  increased productivity, stability/consistency of conditions, predation, spatial  heterogeneity76. What is the equilibrium theory of biogeography? states that the number of  species (species richness) on an island balances regional processes  governing immigration against local processes governing extinction 77. How we distinguish colonization and extinction rate Colonization begins=rate of  colonization decreases 78. Are more species found on large or small islands? Why? Large because more resources 79. Are more species found on islands near the mainland or far away? Why? mainland  80. What kind of energy can organisms use? What kind of energy can they not use? Can use  chemical­bond or light energy, cannot use heat What are heterotrophs and autotrophs? In which trophic levels is each  found? Heterotrophs are organisms that cannot produce their own food/energy.  Found in all levels except primary (level 1) Autotrophs: can produce their own food/energy. primary producers What are the two different types of autotrophs? Chemoautotrophs:  obtaining energy by means of inorganic oxidation reactions Photoautotrophs: use light as their source of energy< most important to ecosystem  function 81. What is primary productivity? What is the difference between gross primary  productivity and net primary productivity? Primary productivity: rate at which solar or chemical energy is captured and made  available to the ecosystem by photosynthesis and chemosynthesis Gross primary productivity: rate which energy is captured and assimilated by  producers in the area Net primary productivity (NPP): rate of energy that is assimilated by producers and converted  into producer biomass in the area - NPP= GPP­respiration 82. What types of organisms are present at each trophic level? ∙ level 1 (primary producers) are at bottom ­ take solar levels and convert to chemical­bond energy  - can be used at higher trophic levels ∙ level 2 are herbivores (primary consumers) - consume level 1/primary producers - provide level 3 food - cows, deer, rabbits, etc.∙ level 3 are primary carnivores (secondary consumers) - provide level 4 food - mole eating grasshopper ∙ level 4 are secondary carnivores (tertiary consumers) - top predators - owl eating mole - lion eating hyena - How is energy lost across trophic levels? 50% chemical­bond energy lost to feces, 33%  lost to everyday activity (metabolism or cellular respiration), 17% remaining goes to  growth (available for next trophic level). Occurs at every trophic level. We use  metabolism energy, assimilate portion available to us, and use small portion into grow  and reproduce - Energy at given trophic level that is made available to next trophic level is only the  energy that has gone to growth and reproduction 83. For each trophic level, how much energy is available from the previous trophic level? What is a trophic cascade? (Contrast bottom-up and top-down and  provide examples of each) consumer-resource interaction that influences  additional trophic levels of the community (top-down and bottom-up) Top-down: carnivores influence sizes of trophic levels beneath them (carnivore  influencing number of herbivores) Trout =Fewer invertebrates because trout eats them. No trout= more invertebrates high pop otters= less urchins and lots of kelp. low pop otters= more urchins and  less kelp (bigger ecosystem issues) Bottom-up: If lower trophic level influences higher trophic levels - Numbers of carnivores increase in biomass with more primary productivity - Fish and dragonfly ex. (no fish=more dragonfly =less pollinators) 84. Why did Tiffany Knight believe a trophic cascade initiated in a pond community could  influence the surrounding terrestrial community? Fish influenced the number of dragonflies.  When larval, live in water where fish can eat them and if they survive then they fly up and  eat pollinators 85. How did the presence of fish influence the number of larval and adult dragonflies in and  around ponds? More fish=less dragonflies86. How did the presence of fish influence the number of pollinators around ponds? Is this an example of bottom­up or top­down control? More fish=more pollinators

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