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Principles of Ecology Lecture Course Outline and Study Guide B10 320 Lawrence S Blumer Department of Biology Morehouse College 2005 Copyright 2005 By Lawrence S Blumer All rights reserved No part of this book may be reproduced stored in a retrieval system or transcribed in any form or by any means without the prior written permission of the copyright holder Acknowledgments Figures and Tables from Ricklefs RE The Economy ofNature A Textbook in Basic Ecology 3rd edition 1993 and 4th edition 1996 WH Freeman and Co were reprinted with permission of the publisher Figures from Eckert R and D Randall Animal Physiology Mechanisms Adaptations 2nd edition 1983 WH Freeman and Co were reprinted with permission of the publisher Preface This outline and study guide is intended to provide students with a means of preparing for lectures taking better focused notes during lecture and reviewing after lectures The outline was written to accompany the text Ricklefs RE The Economy of Nature A Textbook in Basic Ecology 5th edition 2000 WH Freeman and Co This outline and study guide is not a substitute for attending lectures and reading the textbook The outline provides most if not all the tables and gures you will see in the lecture course so you will not need to spend time copying tables and figures into your notes and instead you can focus on experimental design data collection and interpretation and hypothesis testing This outline is intended to free you from trivial note taking and to better enable you to concentrate on understanding the major concepts and principles in Ecology iii Table of Contents Section I Outline Section I Review Problems and Sample Examination Questions Section II Outline Section II Review Problems and Sample Examination Questions Section III Outline Section 111 Review Problems and Sample Examination Questions Section IV Outline Section IV Review Problems and Sample Examination Questions Literature Cited Answer Key for Problems and Sample Questions 25 29 67 71 123 127 209 213 217 Ecology Lecture Outline and Study Guide Morehouse College B10 320 Section I Outline Introduction to Course Ecological Limiting FactOIS The Meaning of Adaptation Ecology and Evolution Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Introduction to the study of ecology Scope of the course Levels of organization of life Atoms Molecules Compounds Cells Tissues r gans Organisms Individuals Populations Species Communities Ecosystems Biosphere Ecology from the Greek Oikos meaning house the immediate environment Term coined by Ernst Haeckel 1869 best known for his biogenetic law ontogeny recapitulates phylogeny Present meaning Study of interactions between organisms and environment The economy of nature the total relations of an organism to both its organic and inorganic environment Biotic and abiotic interactions Levels of interest in modern Ecology Individual organism or cell 39 ctions with environment interactions between living things Populations a group of individuals of one species presence or absence of a species at a given site abundance census change over time Communities groups of populations cture diversity change over time Ecosystems groups of communities ux in energy and matter Modern Ecology is interdisciplinary a synthetic science that draws from and builds upon the study of genetics physiology biochemistry evolution and behavior Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Mathematical models are important in the study of ecology because models can help us simplify complex phenomena and help identify critical variables in complex interactions such as population growth competition and predation Types of organisms Autotrophs Heterotrophs Animals Plants Protista Fun i Monera Bacteria and Cyanobacteria Archaea non bacterial prokaryotes General principles conformity to the laws of thermodynamics physical environment controls productivit ecological communities regulated by population processes organisms change over time evolution Populations are not static Populations change over time Organism distributions distributions neither random nor homogeneous most distributions are restricted patc organism often appear to fit their environment form fits function why Natural selection and evolution Process of evolution by natural selection requires phenotypic variation 39 underlying genetic variation heritable variation differential reproduction and or differential survival to age of reproduction caused by selection 39 differential production of descendants due to differences between individuals in their interactions with the environment Interactions between an individual and its environment result in natural selection which determines individual fitness Organisms in populations change over time 2 they evolve Individuals may be well suited to their present environment and may be considered adapted to their present environment because it is similar to the environments experienced by ancestors Ecology Lecture Outline and Study Guide Morehouse College B10 320 Organisms do not evolve for the present or the future change is a consequence of the past Fitness is the relative success of an individual in a given population and selection is between better and worse Perfection need not occur Yet there is often a striking match between form and function Causes for selection Darwin s Hostile Forces of Nature factors that cause selection weather climate predators parasites and diseases resources shortages including mates These hostile forces can also described as Ecological Limiting Factors Limiting Conditions Limiting Resources Conditions not consumed or used up by other organisms not made unavailable or less available by other organisms climate and weather physical environment abiotic environmental factors temperature relative humidity RH hydrogen ion concentration pH salinity wind speed stream water flow velocity pollutant concentration Resources something consumed used or incorporated or transformed something eaten incorporated in biomass using it makes it unavailable or unusable for other organisms reuse may occur after a period of use by another organism water nutrients C N S K P minerals food mates shelter solar radiation Ecology Lecture Outline and Study Guide Morehouse College B10 320 Major nutrients required by organisms Ricklefs 1996 p 41 Table 21 Element Function Nitrogen N Structural component of proteins and nucleic acids Phosphorus P Structural component of nucleic acids phospholipids and bone Sulfur 5 Structural component of many proteins Potassium K Major solute in animal cells Calcium Ca Structural component of bone and of material between woody plant cells regulator of cell permeability Magnesium Mg Structural component of chlorophyll involved in the function of many enzymes Iron Fe Structural component of hemoglobin and many enzymes Sodium Na Major solute in extracellular uids of animals Solar radiation a critical resource arriving energy varies With latitude highest at the equator see Ricklefs 1996 pp 80 and 81 Fi g 41 and 42 varies With degree of atmospheric scattering and reflection at leaf surface light can be re ected filtered and transmitted absorbed eukaryotic chloroplasts absorb light between 380nm and 710nm Visible light spectrum 56 of incident radiation is outside Visible range photosynthetically active radiation PAR 400nm 700nm prokaryotic chlorophylls absorption peaks at 800nm 850nm and 870 890nm Ecology Lecture Outline and Study Guide Morehouse College B10 320 Spectral distribution of sunlight Ricklefs 1996 p 45 Fi g 213 Higher energy Lower energy HT 600 e U a E 400 8 E G 1 s H 200 03 Ultraviolet Attopof atmosphere Visible PAR 04 05 07 Wavelength uin 10 20 100 Biological energy flow is an open system not a cycle Maj or energy transformation processes Cellular respiration gtgtgtgtgtgtgt energy Photosynthesis 6C02 121 120 energy 709kcal gtgtgtgtgtgtgtgt 6le06 602 61 120 Light intensity energyunit timeunit area Ricklefs 1993 p 39 Table 22 Source M G Barbour H Burk and W D Pitts Terrestrial Plant Ecology Benjamin Cummings Menlo Park Calif 1980 Measurement Units Typical value langley 1y 1 cal cm 2 700 1y 1 1 watt 1 J 5 1 1000 W m392 einstein E 6 X 1023 photons 2000 uE m 2 5 1 200 nE cm 2 s Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Photosynthesis rate as a function of light intensity The compensation point is the light intensity at Which the rate of photosynthesis just compensates for the maintenance needs of the organism cell respiration rate Ricklefs 1996 p 46 Fig 215 Saturation level Photosynthesis carbon fixed Respiration rate carbon lost Compensation Saturation point point Light level Water absorbs light energy and scatters light In sea water At 10m the energy of Visible light decreases 50 At 100m the energy of Visible light decreases to lt7 Red is absorbed first Blue and Violet scatter easily Green penetrates water best Euphotic zone Depth to Which photosynthesis exceeds respiration in water Rarely the compensation point the bottom of the euphotic zone is as deep as 100m Examples very clear ocean or lakes near equator ln highly turbid waters the compensation point may be reached at lm Major Essential Elements Calcium Ca Iron Fe Nitrogen N Magnesium Mg Potassium K Phosphorus P Sodium Na Sulfur S Limiting Nutrient Elements In aquatic freshwater environments nitrogen and phosphorus ln marine saltwater environments iron ln terrestrial environments nitrogen and phosphorus calcium Other Essential Resources Carbon Dioxide Not limiting Oxygen Can be limiting in water Water Often limiting in terrestrial environments Ecology Lecture Outline and Study Guide Morehouse College B10 320 Limitations for one essential resources can in uence the availability of other essential resources This is the case among terrestrial plants for the relationships between photosynthetic rates water loss and gas exchange Photosynthetic Capacity and Water Conservation Photosynthesis rate varies widely among species 100x even with light saturation and all other resources in abundance This variation is due in part to differences between plant species in the biochemistry of carbon fixation in photosynthesis Calvin Cycle Plants can be categorized as having C3 C4 or CAM metabolism Photosynthetic Rate Water Loss and Gas Exchange Specializations and Compromises Among Plants 1 Short life high photosynthetic rate when water abundant dormant at other times seed stage desert annuals 2 Long life leaves produced when water abundant leaf drop during droughts winter or dry season deciduous woody plants 3 Leaves long lived transpire slowly tolerate water deficit but have low photosynthetic capacity woody evergreens evergreen desert shrubs 4 C4 photosynthesis increased efficiency of carbon dioxide use per unit of water loss but inefficient at low light intensity not shade tolerant high temperature optima adaptation for water conservation and efficient nutrient capture arid tropical and saline environments see figures on next page 5 CAM photosynthesis Crassulacean Acid Metabolism control of water loss by limiting atmospheric carbon dioxide capture to night hours when water transpiration rates are at a minimum stomata are open at night and are closed during the day good water conservation but there are limits on photosynthetic capacity arid high elevation windy environments Ecology Lecture Outline and Study Guide Morehouse College B10 320 Crassulasian Acid Metabolism CAM Major steps in the capture of carbon dioxide in CAM plants Atmospheric carbon dioxide is brought into the plant at night When the stomata are open In the daytime stored reserves of malic acid and oxaloacetate are broken down to release carbon dioxide inside leaves for use in the CalVin Cycle but gas exchange to the atmosphere is minimal Abbreviation key RuBP ribulose bisphosphate 21 5C compound PGA phosphoglycerate two molecules of a 3C compound PEP phosphoenolpyruvate 21 3C compound OAA oxaloacetate 21 4C compound Malate malic acid a 4C compound Water loss is controlled in this system by mean of temporal separation of carbon dioxide capture from the atmosphere and the addition of one carbon to RuBP in the first step of the CalVin Cycle Ricklefs 1996 p 69 Fig 39 Malate OAA gt accumulates PGA at night C02 v RuBP Pyruvate Glucose NIGHT DAY Ecology Lecture Outline and Study Guide Morehouse College B10 320 C 4 Photosynthesis Comparison between C3 and C4 plants showing the differences in the physical distribution of chloroplasts in the leaves and differences in first steps of atmospheric carbon dioxide capture for photosynthesis Abbreviation key RuBP ribulose bisphosphate 21 5C compound PGA phosphoglycerate two molecules of a 3C compound PEP phosphoenolpyruvate 21 3C compound OAA oxaloacetate 21 4C compound Pyr pyruvate 21 3C compound Water lOSS is better controlled in C4 plants by physically separating carbon dioxide capture from the atmosphere and the addition of one carbon to RuBP in the first step of the CalVin Cycle Water loss is minimized in this system because the atmospheric carbon dioxide capture step is catalyzed by the enzyme PEP carboxylase which has a higher affinity for carbon dioxide than does the enzyme RuBP carboxylase Ricklefs 1996 pp 68 and 69 Pi g 37 and 38 C3 Plants C 4 Plants Mesophyll cell 02 co2 fieme a Bundle sheath cell Mesophyll cell Ecology Lecture Outline and Study Guide Morehouse College B10 320 Ecological Niche Hutchinson 1957 The set of conditions and resources minimum and maximum values that are limiting to a population of a given species This is an n dimensional hyperspace The fundamental niche is the niche de ned by abiotic factors alone The realized niche is the fundamental niche with biotic factor limitations superimposed The realized niche is typically smaller than the fundamental niche Two or three dimensions are typical in niche descriptions see Ricklefs 1996 p 107 Fig 54 Limiting Conditions and Resources Generalizations 1 Lethal conditions may limit distributions but such conditions need only occur occasionally 2 Distributions are more often limited by regularly suboptimal conditions rather than lethal leading to reductions in growth reproduction or increased predation 3 Sub optimal conditions act by altering outcomes of biological interactions 4 Sub optimal conditions often interact with other factors determining which single condition is critical can be difficult 5 At the edge of a species distribution individuals occupy patches most like the conditions in the center of that species range 6 Evolutionary responses tend to modulate effects of suboptimal conditions Ecology and Evolution What is changing as a result of evolution Phenotypes Changes in phenotypes is reflected in qualitative and quantitative aspects of interactions between organisms and their environment What is the phenotype Any aspect of an organism except the information encoded in the genetic materials genotype Genotype Environment gtgtgtgt yieldsgtgtgtgtgtgtgtPhenotype Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Phenomena of special interest Organic diversity number of different species Patterns in nature distribution and abundance Adaptation close fit between form and function aspects of phenotypes seem formed for specific functions products of evolution by natural selection Evolution is change in phenotypes over time long term change Involves changes in gene allele frequencies in a population Evolution is measured in population change cumulative genetic change is the result which is re ected in phenotypic change Importance and Sources of Phenotypic Variation Natural selection occurs when there is phenotypic variation regardless of the source but only variation with a genetic basis phenotypic differences caused by genotypic variation can be the source of evolutionary change What causes phenotypic variation Since the phenotype is the product of an interaction between information the genotype and the environment variation in either genotypes or environments can cause variation in phenotypes All traits have a genetic background but not all differences between individuals are due to genetic differences Imagine a plant species with mono hybrid genetics for height semi dominant allelic interactions dosage effects and strong environmental effects on height Given a population that is isogenic all individuals have the same genotype and homozygous there will still be variation in height but the variation will be due entirely to environmental variation Ecalugy mm mum and sway om Mmehmlse Callzge 510 32a Gwenamthzr papulaonnwnh Mu 3 le Aard mequal mquzncyard gun mam manrg thhm mm papulanan than shnmdhe mu gumypes pmmeammm at 12 m gvenhelaw m papula nms pulygemc msmme thanmnz gemtype Amusmpmmgm A tan mim39ma un shun mm Gemtypes AA A u mim39maonn 51mg mmm M1212 zquznmzs Gemtype zq lznnzs Flzqmncy muyams m plam hzxg m mgemc and pulng papulaonns wnh mung envnunmzntzl m uznces an phzmtypw explessnn l nhgxmi I39ayuhumu Number SIM nu Gum wv A An A MN mum Number my mum Shun um um nmhpapmm 2mm my sxmdaxphzmtypw valmoan mm at speci c hzlgh s mmnym darlzmnumz cum Eculngy Leanne ohmhe aha Smdycnnde Mmehause Cu ege E10 32a 3212mm can and mu uncut m buthxsugemc aha pulygenm papu a um Nu phehmypm change can uncut mLhe Eugen papulaunn s a mum hf seleeueh Nu ewluunncanuccur m the Eugen papu aunn odysexeeuehmms Ihnse vanaunnhas a 32mm basis pexygehm papu aunn hencehxe vanaer can esuum phenmypm Change ewlu marychange Forms Dfselecunn aha lesulung farms hf evaluan The m ehey dsmbuuuns shew haw papmanahs lespund h 5212mm assuming that Lb observed phenmypm vananun lesul39s m pen um gemtypm vananun pubgems pupl aunm The shaded ales hf eanh dumbunm mines the heganve munnufselecnun fur example pleda un an the talbsurdwldmls m a papu a un ohm mm Dmuhmmnx fur h mm n 2 Mk A WW 2 LA A rwumm Chum Ruuhm sum g e e z The muses fur hem selec un ue causes fuxdx elennal smmhhmepmauweh ale he hnsule fumes ufmtule hmmngresaumes andwrdmuns Ecology Lecture Outline and Study Guide Morehouse College B10 320 Examples of directional selection and directional evolution antibiotic resistance evolution in gonorrhea TB Salmonella Shigella pesticide resistance evolution in malaria mosquitos Anopheles boll weevils herbicide resistance evolution in agricultural weeds Example of stabilizing selection and stabilizing evolution sickle cell hemoglobin and malaria resistance in humans Example of disruptive selection and disruptive evolution Adaptations are products of evolution by natural selection Adaptations are features of an organism that enable it to confront the Hostile Forces of Nature The functions of adaptations are survival and reproduction Does Natural Selection have a goal No selection does not have a specific goal Selection acts on the phenotypic variation that is present the best of the alternatives available is the phenotype that is most successful The best alternative phenotype depends entirely on the Hostile Forces of Nature at a given place and time and the other phenotypes that are present Example of Evolution and Natural Selection Industrial Melanism Cryptic Coloration and Environmental Change Organism Peppered Moth Biston betularia Variation in wing and body color and color pattern see Ricklefs 1996 p 383 Light color morph white or light tan color win gs and body with dark markings spots and irregular lines somewhat like pepper sprinkled on paper Dark color morph dark brown or black body and wings melanistic form This variation has a genetic component and involves a single gene Spontaneous mutation in both directions occurs at low frequency so dark morph parents rarely produce light morph offspring and light morph parents rarely produce dark morph offspring In pre industrial England the light morph dominates in the collections of natural historians and tree trunk natural perches for this moth species are covered with lichens making the perches light in color Based on extensive natural history collections made in Manchester England 1848 first dark morph specimens captured in Manchester area 1895 collections consist of 98 dark morph Ecology Lecture Outline and Study Guide Morehouse College B10 320 During this same time pollution from coal burning industrial revolution was killing lichens on tree and covering tree trunks with soot 1937 EB Ford proposed that differential predation on dimorphic moths depends on the color of the perches 1950 HBD Kettlewell performed experiments to test the hypothesis that the change in moth color morphs was due to natural selection differential predation Hypothesis Cryptic camouflaged moths will be at lower predation risk than non cryptic moths Lower Predation Risk Risk Risk Lower Risk Prediction Birds take non cryptic morphs more frequently than the cryptic morphs OIl Hypothesis Cryptic camouflaged moths will survive longer in nature than non cryptic oths Prediction When both moth morphs are marked and released in nature the more cryptic morph will be more readily recaptured than will the less cryptic morph A given trait may be an adaptation in one environment and not in another Mutation keeps reintroducing the rare color morph in all populations Natural Selection does not have a goal Differential survival and reproduction simply occurs among the individuals in a given population The outcome of selection depends on the specific environment at a given place and time and the phenotypes present in a given population 16 Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Natural selection is not the only means by which evolution can occur Potential causes for evolutionary change are 1 Natural Selection 2 Mutation random process but the source of all variation 3 Drift random process 4 Migration random process Natural selection is the principal guiding force in evolution 1 Altering the direction of selection alters the direction of change 2 Causes of mutation are independent of the causes for selection utation does not guide change Mutations do not respond to need 3 Only the causes for selection remain consistently directional for long time periods What is the purpose of life Is there a singular goal No Is there a singular consequence Yes If evolution by natural selection is the major force molding phenotypes then All organisms must be striving to do one thing maximize their genetic representation in future generations There is no single best means of achieving this but in general organisms are sel sh Natural Selection and Selfish Phenotypes Natural Selection cannot possibly produce any modification in a species exclusively for the good of another species though throughout nature one species incessantly takes advantage of and profits by the structures of others If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species it would annihilate my theory for such could not have been produced through natural selection Darwin s Challenge Charles Darwin 1859 The Origin of Species Ecology Lecture Outline and Study Guide Morehouse College B10 320 Yet organisms do not always seem to behave sel shly Swollen thom acacia plants Acacia collinsii and A cornigera in Central America and acacia ants Pseudomyrmax spp found in association with these plants have some unusual characteristics Swollen thom acacias are trees and shrubs that produce and hold leaves year round unlike closely related plants that are deciduous and drop leaves in the dry season leaves provide year round shelter for acacia ants see Ricklefs 1996 p 415 Fig 1814 produce swollen thorns on stems much larger than those found on other Acacia s ecies used as nesting sites by acacia ants produce Beltian bodies leaf tip protein and lipid structures which seem to serve no function for the plant collected by acacia ants and fed to ant larvae produce extra oral nectaries year round nectar carbohydrate and water production at the base of leaf petioles which are not important in attracting pollinators nectar is used as food by the acacia ants see Ricklefs 1996 p 416 Fig 18 15 These structures are produced by the swollen thom acacia apparently for the exclusive good of the acacia ants Acacia ants live their entire lives associated with a given swollen thom acacia plant The ants provide the swollen thorn acacia plant with competitor removal seedlings that sprout under the canopy of a given acacia plant are cut down by the ants from that acacia and branches of other plants that touch the acacia plant are cut back herbivore protection unlike other Pseudomyrmax species which are diurnal acacia ants are active 24 hours and prevent and discourage herbivory by both insects and vertebrates on the acacia plant they occupy This is an example of a mutualism The swollen thorn acacia survive better when the ants are present than when the ants are absent The swollen thorn acacia ants do not live anywhere but in acacia thorns Each species is ultimately behaving sel shly because they benefit from the aid they give to the other species Types of Interactions Bene t Harm No Effect Bene t Mutualism Predation Commensalism Harm Predation Competition Amensalism No Effect Commensalism Amensalism Neutralism Are all organisms biologically sel sh Does this general consequence extend to the molding of individual phenotypes Are individual organisms selfish Ecology Lecture Outline and Study Guide Morehouse College BIO 320 How do individuals reproduce An individual may in uence allele frequencies in future generations by 1 Production of offspring by that individual direct reproduction 2 Influencing the survival and reproduction of individuals carrying genes identical by descent indirect reproduction These influences are called Inclusive Fitness Effects WD Hamilton 1964 or Kin Selection Examples of Inclusive Fitness Effects Parental care Helpers at the nest cooperative breeding birds and mammals Eusocial insects Hymenoptera Isoptera Aposematic coloration Inclusive Fitness Effects Individuals carrying genes identical by descent are relatives family members Genetic relationships can be expressed as the coefficient of relationship r the proportion of genes identical by descent Ecology Lecture Outline and Study Guide Morehouse College B10 320 Inclusive Fitness Effects Given sexually reproducing diploid organisms Relationship Type Coefficient of Relationshipr Parent Offspring 05 Full Siblings 05 on average range 0 10 Grandparent Grandchild 025 Uncle Aunt Nephew Niece 025 First Cousins 0125 Altruism Behavior benefiting another individual while being detrimental to the individual providing the benefits Benefits and detriments are defined in terms of survival and reproduction Altruism is defined in much the same way that Darwin s Challenge is framed This is behavior that we predict cannot be produced by natural selection Aiding relatives is an alternative means of individual reproduction which depends on 1 The magnitude of r The greater the value of r the more likely 2 Magnitude of benefit to aid receiver includes reciprocity 3 Magnitude of cost to aid giver depends on alternative activities 4 Magnitude of benefit to aid giver from sources other than the aid receiver Natural selection molds phenotypes Behavioral traits may appear selfish or altruistic but all are ultimately selfish in an evolutionary sense Can altruism evolve by means of natural selection magine a cleaner fish species in which individuals get no benefits from cleaning parasites from other fish species but cleaners did sustain some costs If there were variation in the cleaner fish population so some individuals were cleaners and others were non cleaners and the variation was heritable which behavioral trait would be most successful in leaving descendents If the process of evolution by natural selection applies to all organisms then it must apply to human too A vulgar theory Does it apply to humans Does altruism occur in human behavior adoption life saving anonymous gifts Behaviors that appear to make no sense today may have clearly been biologically selfish in their original context Humans are not living in the environments in which we evolved physical or social Context environment is essential for understanding the evolution and maintenance of phenotypic traits An evolutionary view of life provides a framework for interpreting ultimate function the origin of phenotypes structure and function The theory of evolution by natural selection enables us to interpret how phenotypes were molded to their present state but this theory does not indicate what should be 20 Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Speciation Species Definition Biological Species Concept A species is a population or group of populations within which there is interbreeding in nature but this group is reproductively genetically isolated from other such populations or groups Species are natural biological groupings In practice groupings are based on easily identified aspects of phenotypes The biological species concept is limited to sexually reproducing organisms A given species identi cation is not precise because our knowledge about interbreeding and gene flow between groups is not perfect P r 39 are not 39 ithin r r 39 there can be spatial isolation separation in space or temporal isolation separation in time Species Formation Reproductive isolation barrier to gene ow One population splits into two populations Forms of Isolation Allopatric geographic or allopatric speciation physical isolation Changes occur in isolation in response to local conditions and chance events The form of physical isolation necessary for reproductive isolation depends on the particular organism involved Parapatric parapatric speciation Reproductive isolation among members of a continuous population without geographic barriers Isolation involves environmental discontinuity such as a soil type change for plant species or host plant change in an herbivore Sympatric sympatric speciation Speciation with overlapping distributions among the two populations that are becoming isolated Isolation may be spatial or temporal Polyploidy formation in plants rare in animals autopolyploidy within a species alloploidy between species Host races insects returning to natal plant species to reproduce Reproductive habitat races fishes and amphibians that return to the site habitat to 21 Ecology Lecture Outline and Study Guide Morehouse College BIO 320 What happens in isolation Isolation alone does not make organisms different from each other reproductive behavior changes temporal or spatial reproductive changes physiological changes Small differences can be magnified at recontact between groups if hybrids are less viable than either pure type This phenomenon is termed character displacement to be considered in detail in section on competition Even when phenotypic differences are great genetic differences can be very small Higher level systematics are groupings of species based on phenotypes similarities and differences shared characteristics that are hoped to re ect evolutionary descent relationships Species grouped in a Genus Genera grouped in a Family Families grouped in an Order Orders grouped in a Class Classes grouped in a Phylum Phyla grouped in a Kingdom Macro evolutionary Phenomena Long term evolutionary change at higher level systematic categories is termed macro evolution geological time scale Speciation one species subdividing diverging to two species Phyletic evolution change within a single line of descent Extinction termination of a given line of descent Extinction In geological time there have been six major periods of mass extinction 500 million years ago Cambrian extinction of 50 of animal families 345 million years ago Devonian extinction of 30 of animal families 230 million years ago Permian extinction of 50 of animal families extinction of 95 of marine species 180 million years ago Triassic extinction of 35 of animal families 65 million years ago Cretaceous extinction of dinosaurs 70 of animal species 10000 years ago Pleistocene extinction of large mammals and birds 22 Ecology Lecture Outline and Study Guide Morehouse College B10 320 Causes of mass extinctions major events in continental drift mountain building periods volcanic activity sea level lowering exposing continental shelves asteroid comet impacts 100 million year intervals human activity explosions habitat destruction overutilization overhunting long term cycles in earth orbit and sunlight intensity Biological factors in uencing likelihood of extinction rarity dispersal ability degree of specialization population density variability trophic status longevity intrinsic rate of population growth 23 Ecology Lecture Outline and Study Guide Morehouse College B10 320 24 Ecology Lecture Outline and Study Guide Morehouse College B10 320 Section I Review Problems and Sample Examination Questions The sexually transmitted disease gonorrhea is caused by the bacterium Neisseria gonorrhoeae This disease used to be treatable with the antibiotic penicillin Penicillin was widely prescribed for that purpose and was even dispensed to individuals thought to be at risk of infection who were not actually infected In 1970 the first strains of penicillin resistant Neisseria were isolated from patients with gonorrhea In 1985 the percentage of gonorrhea cases in the United States caused by penicillin resistant Neisseria was 1 9000 cases of penicillin resistance but by 1990 the percentage had increased to almost 9 59000 cases of penicillin resistance The percentage of Neisseria infections that are resistant to penicillin continues to increase Describe the roles of mutation and natural selection in the phenotypic change observed in Neisseria gonorrhoeae What kind of selection occurred in Neisseria gonorrhoeae populations Draw a frequency histogram to illustrate your answer List and describe the requirements for evolution by natural selection 25 Ecology Lecture Outline and Study Guide Morehouse College B10 320 Extinction is a macroevolutionary process in which all individuals in a given group species stop leaving descendents and eventually disappear Is this an important phenomenon in the history of life on earth Explain Name ve factors that may increase the likelihood of extinction What is the function of photosynthesis specializations such as C4 photosynthesis and CAM in some plant species Explain your answer 4 Name and describe Darwin s Hostile Forces of Nature What is the relationship between the Darwin s Hostile Forces and ecological limiting conditions and resources What is the role of the Hostile Forces and limiting factors in the process of Natural Selection 5 What is the compensation point in photosynthesis Under what circumstances in nature would photosynthetic organisms be at the compensation point Draw a fully labeled graph showing the rates of photosynthesis and respiration as dependent variables to help illustrate your answer 26 Ecology Lecture Outline and Study Guide Morehouse College BIO 320 Multiple Choice choose the one best answer 6 Compared to C3 plants C4 plants are able to a reduce water transpiration from leaves b capture carbon dioxide at a faster rate c separate carbon fixation from the Calvin Cycle d all of the above Speciation requires some form of isolation between populations because a all evolution requires geographic isolation b species are defined by reproduction isolation c mutation will occur most rapidly in isolation d evolutionary forces are too weak in sympatry The causes for natural selection are known as a 39mitin g conditions b resource shortages c hostile forces of nature d all of the above One of the requirements for the occurrence of natural selection is phenotypic variation In the absence of phenotypic variation evolution a cannot occur by natural processes b may occur by disruptive selection c cannot occur by natural selection d cannot occur by molecular processes Changes in populations of many species of gut inhabiting bacteria during the past 20 years in which cells have become resistant to almost every known antibiotic is an example of a mutation directing phenotypic change b selection causing phenotypic change c antibiotics causing mutational change d all of the above Oxygen gas is essential for cellular respiration in most organisms yet this gas is readily available in terrestrial environments In terrestrial environments oxygen can therefore be considered a a limiting resource b a required resource c a biotic condition d an abiotic condition 27 Ecology Lecture Outline and Study Guide Morehouse College B10 320 28