BSC 385 | Study Guide | Detailed
BSC 385 | Study Guide | Detailed BSC 385
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This 13 page Study Guide was uploaded by Isabella Ryerson on Monday October 3, 2016. The Study Guide belongs to BSC 385 at University of Alabama - Tuscaloosa taught by Dr. Benstead in Fall 2016. Since its upload, it has received 159 views. For similar materials see Ecology and Evolution in Biology at University of Alabama - Tuscaloosa.
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Date Created: 10/03/16
Ecology and Evolution Exam 2 Study Guide Clicker questions in red Lectures 17 and 18 not included as I was out for surgery Lecture 9 Name the important factors in marine systems o Salinity o Temperature Depends on the angle of the earth Hotter near the equator Cooler closer to the poles o Pressure o Light availability o Oxygen content o Most but not all factors change with depth Some increase but others decrease Ocean Domains o Dictated by temperature rather than biogeographical realm o Very few barriers that prevent dispersal o Things are more likely to spread out based on abiotic conditions The ocean has some of the world’s most unusual ecosystems o Black smokers Primary production that fuels all other ecosystems occur in the euphotic zone o The start of the food web Costal Communities o The most productive and diverse marine communities occur in shallow water near the shore o Continental shelf The area of seabed around a large landmass where the sea is relatively shallow compared with the open ocean Geologically part of the continental crust. o Coral reefs Most diverse marine community Occur in subtropical regions Three basic types: o Fringing reefs: develop on rock substrate near islands and continents and project directly from the shore o Barrier reefs: develop parallel to the shore and form a lagoon between he reef and the shore o Atolls: island reefs surrounded by deep ocean Develop as corals and sediments accumulate, gradually reaching the oceans surface Some form as volcanoes rise or when the sea level drops o Estuaries A partially enclosed body of water connected directly to the ocean that occurs near the mouth of a river Salinity gradient where freshwater meets ocean water Freshwater (less dense) floats above salt water o Salt marshes Estuarine communities that occur where a barrier island protects the bay from wave action Gradually sloping shoreline Allows tide the stretch across wide flats Because of its high salinity, few species can live there Salt grass pickle weed o Mangroves Occur along flat tropical and subtropical shorelines with a soft bottom Mangroves are tolerant to the extremely salty water in this region and the different species form a gradient, with the red mangrove occupying the saltiest area Produce salt tolerant seeds the germinate while still attached to the plant Maze of roots and sediments is an important breeding habitat for shrimp and mangrove snappers Also reduces the impact of storms and waves on coastal communities near by o Rocky Intertidal Supports a diverse assemblage of plants and sessile invertebrates, which in turn support mobile invertebrates and fish Strong vertical gradient of environmental conditions Temporal fluctuations of conditions due to the tidal cycles One of the harshest areas on earth Lecture 10 A case study of social behavior o Belding’s Ground Squirrels Alarm calls Warn other colony members of a particular presence Greatly increases the risk in the caller This is called altruism Why do some organisms do this? How does behavior evolve? o Behaviors contribute to fitness o Behaviors that are genetically controlled are subject to natural selection o Like other traits, each behavior has both a fitness cost and benefit o Behaviors are result of genetic make-up as well as environment and experience of an individual Few behaviors are purely genetically fixed or purely the result of the environment A good example is bird song. It is both learned and genetically coded for Behavioral plasticity is itself an adaptation o Contributions to the environment and genetics contribute to heritability Heritability o Broad-Sense Heritability (H^2): proportion of the total variance driven by genes-due to genetic differences among individuals Ranges from 0-1 o Narrow-Sense Heritability (h^2): proportion of total phenotypic variance that is due to additive genetic variance, V A. VA drives resemblance between parents and offspring Ranges from 0-1 Estimates of Heritability o If heritability is high then there is a strong relationship between parents and offspring o Estimates in humans can be obtained by studying twins Monozygotic = identical Dizygotic = fraternal Monozygotic twins share traits which shows that traits are driven by genes Heritability affects evolutionary rate o The response to selection depends on the combination of heritability and intensity of selection o High heritability responds to natural selection more rapidly o Low heritability causes natural selection to be weak o If h^2 is high, the rate of evolution is greater o The heritability of “head number” in humans is low This is because there is little to no variance in head number Heritability can’t be high because there is little to no variance All of the people with two heads either die or just aren’t born. o What are the fundamental mechanisms of behavioral interactions? Stimulus-Response: a specific behavior is elicited by a specific stimulus Baby birds (who are blind) know to open their mouths when their mother or father arrives Birds doing a ritualistic dance before mating Communication: any action by one individual that alters the probability of behavior in another Uses many different signals: visual, auditory, olfactory, or tactile senses are common Communication may convey either discrete or graded information o Discrete: general alarm call o Graded: alarm call specific to predator Many animals have evolved to communicate through graded communication Natural selection: evolution of adaptations that lead to higher fitness Sexual selection: some traits may improve reproductive success while reducing survival A peacock’s tail makes it more prone to predation because of how bright and heavy it is Sexual selection results from asymmetries in reproductive effort o Sexual selection acts on the sexes differently Mothers make a larger parental investment than the fathers Increases the fitness of the offspring but at the expense of addition offspring In most animal’s eggs/pregnancies are more expensive than producing sperm Whichever individual has the larger gamete is the female Lecture 11 “Battle of the Sexes” o Females Choose their male-limited to amount of offspring Incur many anatomical, physiological, and energetic costs of reproduction o Males Sperm is energetically cheap Less choosy Male fitness increase with the number of females they inseminate o This helps to explain the sexual dimorphism in many species Elephant seals: males are about 4x the size of the female Bateman’s Principle o Whenever there is competition, there is more variation in reproductive success o Related to sexual dimorphism Female choice o Females decide which male they want to mate with Male-Male competition o Three typical strategies Combat Post-Copulatory competition Infanticide Interactions between natural selection and sexual selection o Balance Hypothesis: male traits are exaggerated by female choice until their overall fitness cost is too high o Truth in Advertising Hypothesis: elaborate phenotypic traits of males are an indicator of overall fitness Types of mating o Monogamy: the practice or state of having a sexual relationship with only one partner Expecting when offspring requires both parents to survive Types of monogamy Social monogamy: female bonds with one male and they share in parental care Genetic monogamy: all offspring are produced by the same pair o Polygyny: a pattern of mating in which a male animal has more than one female mate Evolves when there is special distribution of females or critical resources o Polyandry: a pattern of mating in which a female animal has more than one male mate Evolves when there is a special distribution of males Fitness benefits of females Nupital gifts (like food) Reduces the probability of mating with a poor quality male Spiders and many other insects do this Marmosets are a rare case of polyandry Lecture 12 Habitat Selection and Use o Microhabitat: subset of the habitat that differs in important abiotic and biotic characteristics o Home Range o Territoriality o Territory size is related to sexual selection a male with a larger territory may attract more females Dispersal o The one-way movement of an individual from the natal area o To avoid in-breeding o Philopatry: lack of dispersal o Saturation Dispersal: dispersal to avoid shortage of important limiting resources such as food or nest sites o Pre-Saturation Dispersal: occurs before recourses become sparse Resources other than food or space are limiting Avoidance of inbreeding for both dispersers and philopatric individuals Migration o Regular movement of individuals o Under environmental and genetic control Social Systems o Three components: Group size and composition Degree of cooperation Mating system Why do altruistic behaviors evolve? o Inclusive fitness: the relative ability to transfer one’s genes, or copies of them, into the next generation Expands the definition of Darwinian Fitness to include shared genes passed on by an individual’s close kin o So with the Belding’s Ground Squirrels: Females are closely related to each other So females are the ones doing the calling Hamilton’s Rule o rB – C > 0 o r = relationship of an altruist (coefficient) o B = fitness benefit to recipient o C = fitness cost of an altruist Mating systems may enhance inclusive fitness, kin selection, and altruism Lecture 13 Patterns of local environmental variation drive intraspecific variation o Environmental conditions are universally diverse and heterogeneous o Aspects of environmental patchiness Magnitude of differences between patches Degree to which isolated Relative size of patches Effects of patch size vs mobility of organisms o Coarse-Grained Environmental Variation o Fine-Grained Environmental Variation Temporal Variability o Temporal variation depends on the amplitude of the change, the speed of the change, and the predictability o Unpredictable variation poses the greatest challenge Adaptations to the local environment o Color polymorphism is a good example Like capaea snails and peppered moths o Adaptations are driven by predation risk Snails that don’t match the background are eaten at a greater rate What is a species? o Biological Species Concept: in sexually reproducing organisms, a species is a group of populations that can interbreed and produce fertile offspring o Ecotype: genetically distinct populations adapted to local environment via natural selection o Subspecies/Race: a local, distinct form that arises due to phenotypic plasticity o Subspecies and ecotypes can interbreed o Where do we classify “ring species”? A good example of a ring species is an orca Some orcas are very different than other orcas Variation within species is driven by environmental variation o Genetically determined differences between populations inhabiting different environments give rise to ecotypes o Non-genetic changes give rise to phenotypic plasticity Factors favoring the evolution of ecotypes o Existence of genetic variation in the trait Fisher’s Fundamental Theorem: the rate at which the mean fitness of a population increases by natural selection is equal to the additive genetic variation in fitness o The intensity of natural selection o Geographical barriers to gene flow Phenotypic plasticity o The development of different phenotypes in different environments by the same genotype o Not all phenotypic differences are adaptive Ay reflect detrimental effects of a poor environment o The phenotypic plasticity involves detection of environmental cues followed by a response of developmental pathways Genetic local adaptation and phenotypic plasticity often co-occur o Melanistic forms Darker bodies High heat absorption Higher body temperature Lady bugs are a good example Lecture 14 How do we measure genetic variation in populations? o Common Garden Experiments: individuals with different phenotypes in the field are grown under similar conditions o Reciprocal transport o Easy with plants but can be done with animals too Stall called “Common Garden Experiments” when dealing with animals o There are different methods like year to year experiments Factors that influence genetic variation o Mutations are the ultimate source of all genetic variations o Once the mutations are there, their frequencies and combinations change due to: Meiosis Natural selection Genetic drift Breeding system Etc o There are other mechanisms that decrease variation and mechanisms that increase or maintain variation Decrease Stabilizing selection Directional selection Inbreeding Genetic drift Increase or maintain Over dominant selection Disruptive selection Frequency dependent selection Outcrossing Migration/Gene Flow Why is sex more common than asexuality? o Sex: two individuals o Asexual: one individual o In some species, sex and asexuality can both be performed Hydra are good examples o Sexual reproduction has a high cost: takes twice as many parents to produce the same number of offspring o Sex is not an evolutionarily stable strategy o Asexual individuals pass on twice as many genes to their offspring—doubles in size each generation o Sexual population size remains the same o Asexual lineages tend to die out quickly but some are occasionally long lived Asexual reproduction compels genomes to be inherited as indivisible blocks There is no way of getting rid of mutations because of this This is why asexual lineages tend to die off o The Red Queen Hypothesis: selection in a constantly changing environment favors sex Sex increases the variability of offspring via new combination of alleles o In a hypothetical organism that had no biological enemies or parasites, what would be favored? Sexual Selection o Sex is not an evolutionarily stable strategy because asexual organisms reproduce more efficiently How do you measure genetic variation? o Wright’s F-Statistics: FI: total for all populations FI: Variance within populations FST: Variance between populations Population bottleneck: extreme form of genetic drift o Catastrophic event leads to less genetic variation o Ne large Ne small o Cure: restore genetic diversity Lecture 15 What is demography? o A quantitative description of the structure of populations o Includes size, age, structure, sex ratios, and growth rate o Major tools include: life tables and fecundity schedules They quantify age-specific patterns in populations What is a population? o A group of individuals of a single species inhabiting a particular area o Many characteristics cannot be applied to individuals like density, dispersion, and age structure The relationship between the ecological and evolutionary population o Ecological population: a group of individuals of a species that occupy a defined area o Evolutionary population: A local group of individuals that mate at random Population boundaries o Important to determine because individuals are not homogenously distributed across the landscape o Can be determined by differences in demography Number of individuals Special distribution Reproductive rate Isolation vs connectivity Connectivity is the link between 2 or more populations by dispersal of individuals o A good example is the white footed mouse It is distributed across distinct but geographically connected habitat types o Connectivity decreases when there are habitat barriers to dispersal Important characteristics of populations o Abundance (Nt): number of individuals of a single species in a population o Density: number of individuals per unit area of volume What is an individual? o The definition of an individual changes with the question o Genet: a genetically distinct individual or clonal colony in a planet population o Ramet: a physiologically distinct individual with in a plant genet o Unitary organism: Exist as separate and distinct individuals o Modular Organisms: develops repetitive patterns of growth of body parts How to quantify population size o Total census Count For large animals, trees Used to count the human population o Lincoln (mark-recapture) method For small, mobile organisms Total population size (N) = number of individuals marked and released (n1) x number of individuals captured number of individuals captured at time t (nm) o Quatrat of transect method For sessile or relatively immobile organisms Indirect, relative measure or abundance, but can be scaled up Spatial distribution of individuals o Random: Individuals aren’t interacting much with each other o Clumped: most common, individuals are either responding positively to each other, attracted to resources, or benefit form living in close proximity o Regular: Negative, antagonistic reactions to each other Quantifying spatial dispersion o Observation o Test: lay a grid and then come up with the distribution by using the Poisson Distribution Describes a population distribution that is randomly distributed Lecture 16 Key demographic characteristics of a population o Age Structure: provides insight into the ecology and history of populations Life tables are used to measure age structure Cohort life table: follows a group of individuals over time Static life table: based on a sample of the population at one moment in time o Not good in populations that experience migration o Can be done by finding bones and measuring the age of them Survivorship curves are also helpful in measuring the age structure Graphically represents the pattern of age-specific survival You can make this out of the life table data o Type 1: Low survival with young High survival until old Mortality increases rapidly Common with mammals o Type 2: Survival is constant Common with small mammals, birds, and lizards o Type 3: Early mortality Mortality decreases with older age Common with fishes, plants, and invertebrates o Organisms that produce many different offspring per parent usually have Type 3 survivorship curves Life tables can be used to calculate age-specific life expectancy (ex) Life expectancy life span Life span: the maximum number of years an individual can potentially live Life expectancy: the expectation of life at a certain age and is affected by the probability of dying at different ages Net Reproductive Rate (Ro) The average number of offspring produced by an individual during their lifetime Ro > 1: the population is increasing Ro = 0: the population is stable Ro < 1: the population is decreasing Ro is the sum of the lxbx column in a life table o Sex Ratio Can vary among and within populations 1 sex ratio: sex ratio at fertilization 2 sex ratio: sex ratio at birth or hatching 3 sex ratio: sex ratio at sexual maturity 4 sex ratio: sex ratio at population Human age structure pyramids are good at showing the sex ratio of populations How do populations change in time and space? o The dynamics of a population depend on: Immigration Emigration Births Deaths Dispersal o Births and deaths are the key internal factors in population dynamics Discrete Nt = NoRo^t Overlapping Nt = N0e^rt r = births – deaths The value of r determines how rapidly the population grows Transition matrix or Leslie matrix can be used to estimate
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