Biology 286: Introduction to Ecology and Evolution Thought/Review Questions, Exams of Nursing

Download Biology 286: Introduction to Ecology and Evolution Thought/Review Questions and more Exams Nursing in PDF only on Docsity! Biology 286: Introduction to Ecology and Evolution Thought/Review Questions Week 1: 1. What does it mean for biological entities to be hierarchically organized? What is an emergent property? Be able to provide examples. What levels of the hierarchy are typically involved in ecological studies? A hierarchical organization is an organizational structure where every entity in the organization, except one, is subordinate to a single other entity. In an organization, the hierarchy usually consists of a singular/group of power at the top with subsequent levels of power beneath them. An emergent property is a characteristic an entity gains when it becomes part of a bigger system. Emergent properties help living organisms better adapt to their environments and increase their chances of survival. Examples: --- In multicellular organisms, cells are arranged into tissues or groups of similar cells that work together to perform a particular function. For example, a single epithelial cell cannot form a protective layer. --- Organs are then formed from the functional grouping of multiple tissues ---Organs that interact may form organ systems capable of carrying out specific body functions: Heart; Blood vessels (arteries, capillaries, veins) ---Organ systems collectively carry out the life functions of the complete organism Levels of Organization: ---Individual ---Population ---Community ---Ecosystem ---Biome ---Biosphere 2. What are the steps of the scientific method? Why can they be applied to questions addressing adaptations or natural selection? Steps: Observation, Hypothesis, Measurements, Results, Conclusion The scientific method can be used to provide an explanation for observable facts. 3. What distinguishes a scientific hypothesis from a scientific theory? A hypothesis attempts to answer questions by putting forth a plausible explanation that has yet to be rigorously tested. A theory, on the other hand, has already undergone extensive testing by various scientists and is generally accepted as being an accurate explanation of an observation. An explanation of a set of related observations or events based upon hypotheses that have been supported multiple times by distinct groups of researchers. 4. What is the difference between proximate and ultimate levels of causation? Be able to provide an example for each. Proximate: Direct effects of external stimuli; direct, immediate causes (think MECHANISM); Proximate causation explains biological function in terms of immediate physiological or environmental factors. ---temperature and photoperiod (the interval in a 24-hour period during which a plant or animal is exposed to light) Ultimate: Evolutionary factors that led to appearance of certain traits (think WHY); Ultimate causation explains traits in terms of evolutionary forces acting on them. ---selective pressure from predation 5. How do Tinbergen’s inform our understanding of proximate and ultimate levels of causation? It suggests that an integrative understanding of behavior must include both a proximate and ultimate (functional) analysis of behavior, as well as an understanding of both phylogenetic/developmental history and the operation of current mechanisms. Explains animal behavior. 6. The changes that have occurred in the horse lineage over 60 million years constitute macroevolutionary changes. How do these relate to microevolutionary changes? Microevolution: changes in ALLELE FREQUENCIES within a population over time, resulting in short-term evolutionary changes within species. Macroevolution: evolution of great phenotypic change that is usually great enough to classify the changed lineage and its descendants to a distinct genus or higher taxon. --- Often microevolution can lead to macroevolution as changes become more pronounced and two distinct species emerge. Both are caused by mutation, genetic drift, gene flow or natural selection. 7. What factors influence how rapidly different organisms may evolve? Evolutionary rates vary among organisms due to: ---Rates of environmental change organisms experience ---The amount of genetic variation within the species ---The size of the population ---The generation time of the population 8. What contributions did Charles Darwin make to our understanding of biological diversity? Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors. Darwin’s theory provided the mechanism for evolution – descent with modification 9. What is the unit of evolution (what evolves)? Population 10. What is the relationship between genetic information flow and evolution? How are genes related to evolution? Selection Coefficient (S): the proportion of a particular genotype that is not represented in the next generation A value of 0.5 means that that genotype has a better chance of surviving than the 0.99 value. A value of 1 is lethal. The 0.99 genotype is less fit and 99% of the individuals do not survive selection event. Week 2: 1. What are the three patterns of selection? Be able to explain them in terms of average trait value, population variability and fitness, and recognize them graphically. Be able to provide an example of each. Directional selection: individuals with an extreme phenotype at one or the other end of the distribution have greater reproductive success/fitness than individuals without that extreme phenotype. Therefore, over time individuals with the extreme trait value will be found at a greater frequency. ---For Example: In many species of Drosophila, males that have larger body sizes have higher mating success (and body size is a heritable trait) ---oyster shells Stabilizing selection occurs when individuals with intermediate phenotypes have greater reproductive success/fitness than individuals with extreme phenotypic values. Therefore, over time intermediate traits will be found at a greater frequency than extreme traits. ---For Example: in many Drosophila species, eggs of intermediate lengths have higher hatching success than those at either end of the distribution. ---plant height Disruptive selection: Individuals with extreme phenotypes at either end of the distribution have greater reproductive success than individuals with intermediate phenotypes. Therefore we get abimodal distribution of phenotypes. ---For Example: in male salmon (Oncorhynchus spp), those maturing at small body size (jacks) have similar fitness to those maturing at larger body sizes (hooknose), while those maturing at intermediate sizes have the lowest fitness. This is because small males fertilize eggs by sneaking fertilizations when females release eggs while intending to mate with larger males, and they mature at a younger age. Hooknoses attract more females and mate more, but they mature at an older age. 2. How can rainfall patterns on the Galapagos Islands act as a selective pressure of finch beak morphology? What are the rainfall effects on beak phenotype? More offspring are produced than can survive because of limited resources such as food and nesting sites. Rainfall patterns acted as a selective pressure to control population size and seed abundance. After the drought, the average beak depth increased in size and the finch population had more finches with greater beak depths in 1978 than before the drought. Beak size increased because the drought reduced the number of seeds and finches with bigger beaks were able to eat the larger and harder seeds so more of them survived. 3. What are the ways, other than selection, that can lead to microevolutionary changes? How do they relate to selection? Mutation, migration, genetics drift. All of these things can lead to natural selection (or changes in allele frequencies) . 4. How do mutations relate to evolution? You may use antibiotic, insecticide or herbicide resistance as an example. Mutations introduce new alleles in to the population due to changes in DNA sequence. They’re usually deleterious but new variation might be adaptive (e.g. insecticide resistance). 5. Be able to explain how parasitoid wasp and bird foraging behavior act as a selective pressure on the size of fly-induced goldenrod galls. The goldenrod gall fly lays its eggs on the buds of goldenrod plants. Larvae hatch from the eggs and then chew through the goldenrod buds and into the stems. The gall fly larvae saliva induces the goldenrod to generate a gall (an outgrowth of tissue, a ball-shaped swelling on the stem). The larva will live inside the gall which provides food and shelter for the developing larva. The larvae are prey of both parasitoid wasps and birds. Wasps selectively prey on larvae inside the smallest galls while birds selectively prey on larvae inside the largest galls. The size of the gall made by the larvae is a heritable trait. Given this information, we can conclude that the trait 'larval gall size' is subject to stabilizing selection. 6. Why are small populations more vulnerable to genetic drift? Smaller populations have larger fluctuations in allele frequency and are more prone to allele fixation. 7. What does it mean for an allele to go to fixation? A fixed allele is an allele that is the only variant that exists for that gene in all the population. A fixed allele is homozygous for all members of the population. 8. Can selection and drift act on the same individual or population? Explain why. Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population, the population violates the Hardy-Weinberg assumptions, and evolution occurs. 9. What is the relationship between genetic drif t and natural selection? Which is likely to be more directional? Why? Both natural selection and genetic drift are mechanisms for evolution (they both change allele frequencies over time). The key distinction is that in genetic drift allele frequencies change by chance, whereas in natural selection allele frequencies change by differential reproductive success. Natural Selection In population genetics, directional selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. 10. What is the adaptive landscape? On what axes is it plotted? Who proposed it? Adaptive landscape: The adaptive landscape is a 3-D representation of fitness of different genotypic combinations; visual model of evolution Proposed by Sewell Wright 11. How does the selective landscape integrate concepts of drift and selection? 23. How can the selection coefficient be calculated using trait values? S = 1 - Relative fitness Biology 286: Introduction to Ecology and Evolution Thought/Review Questions: Spring 2018 WEEK 3: 1. What is the difference between primary, secondary and tertiary scientific literature? What do they all have in common? Primary sources are original materials on which other research is based. They are usually the first formal appearance of results in physical, print or electronic format. They present original thinking, report a discovery, or share new information. Like diaries, letters, and speeches. Secondary sources are less easily defined than primary sources. Generally, they are accounts written after the fact with the benefit of hindsight. They are interpretations and evaluations of primary sources. Secondary sources are not evidence, but rather commentary on and discussion of evidence. Like dictionaries, magazines, and biographical works. Tertiary sources consist of information which is a distillation and collection of primary and secondary sources. Like textbooks, fact books, and almanacs. All Peer-reviewed information 2. Consider two traits that have different heritability values. How can selection act on these traits? Will it differ? Heritability: the proportion of phenotypic variance attributable to genetic variance Because heritability is a proportion, its numerical value will range from 0.0 (genes do not contribute at all to phenotypic individual differences) to 1.0 (genes are the only reason for individual differences). In different words, if everyone is treated the same environmentally, then any differences that we observe will largely be due to genes; heritability will be large in this case. However, if the environment treats people very differently, then heritability may be small. 3. Quantitatively, what is the difference between absolute and relative fitness? Absolute fitness: the survivorship and reproduction of each genotype in a population. ---i.e. absolute number of each genotype present Relative fitness is the ability of one genotype to survive and reproduce relative to the best genotype 4. What is the difference between the censused and effective population size? Why might they differ? Censused Population Size: the population you actually count; number of total individuals in a population Effective Population Size: the size of an "ideal" population of animals that would have the same rate of inbreeding or decrease in genetic diversity due to genetic drift as the real population of interest.; The effective population size is the size of an ideal population (i.e., one that meets all the Hardy-Weinberg assumptions) that would lose heterozygosity at a rate equal to that of the observed population. 5. Be able to calculate effective population size if given the formula. What factors can reduce effective population size, and why? Example - Sample deer population in four consecutive years: 60, 200, 150 and 20 individuals ---1/Ne = (1/4)(1/60 + 1/200 + 1/150 +1/20) ---1/Ne = (1/4)(0.0167 + 0.005 + 0.0067 + 0.05) 1/Ne = (1/4)(0.0784) ---Ne = (4/0.0784) = 51.02 = 51 Factors that reduce effective population sizes: ---Unequal numbers of males and females ---Not all of individuals reproduce ---The number of offspring produced differs from random expectations ---mating is not random ---the number of breeders changes from one generation to the next Why does it matter? ---Can be used as a predictor of long-term population ‘health’ and persistence ---Can inform management decisions 6. What is the difference between an endangered and threatened species? How does effective population size inform that status? Endangered - any species that is in danger of extinction throughout all or a significant portion of its range; Threatened - any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. Helps conserve species 7. For grizzly bears in Yellowstone National Park, how do census and effective population size values compare? 8. What is a population bottleneck and now does the genetic diversity of the population following the bottleneck compare with that preceding it? Why is this important? Bottleneck: evolutionary events in which a large portion of the population is lost or prevented from breeding The genetic make-up after bottleneck may not represent the diversity that was present before the bottleneck. This can cause lower levels of genetic variation. Without genetic variation, a population cannot evolve in response to changing environmental variables and, as a result, may face an increased risk of extinction. 9. What is a founder effect? How might it influence the genetic differentiation of a population relative to its source population? Founder effect: founding population has different genetic make-up than source population they were derived from; the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.: Example polydactyly When a newly formed colony is small, its founders can strongly affect the population's genetic makeup far into the future. Small population sizes lead to inbreeding and reduce genetic diversity. 10. What is inbreeding and why is it potentially deleterious? Inbreeding: mating between relatives Inbreeding results in homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased biological fitness of a population (called inbreeding depression), which is its ability to survive and reproduce. 11. What is a biological species? A group of interbreeding organisms that have an isolated gene pool Groups of interbreeding populations that are evolutionarily independent of other populations 12. Why is the number of species on the planet NOT static? Static: stationary or fixed The number of species on Earth is an estimate; new species are being discovered each year 13. Among recognized animal species, which group contains the largest number of species? Anthropoda Insects make us about 75% of known species 14. If you think you discovered a new species of flowering plant and a new species of beetle, how would you go about getting them recognized as new species? Would you have to do anything different for the recognition of the two discoveries? What it takes to recognize a new species: •a description of the news species is required ---must defined what features (behavioral, anatomical, genetic) mark it out as being unique and new ---must allow it be distinguished from close relatives ---Details of the origins of the species type and subtypes (alternative life stages, color patterns, etc.) must also be given: how, where and when were they collected? In what kind of environment were they collected (fossilized in rock, etc.)? Factors that affect the process of speciation are: --- Geographical isolation: Caused by various types of barriers such as mountain ranges, rivers and seas. Leads to reproductive isolation due to which there is no flow of genes between separated groups of population. ---genetic drift: Caused by drastic changes in the frequencies of particular genes by chance alone. Genetic drift with changes in the gene flow imposed by the isolation mechanism acts as an agent of speciation. ---natural selection: Process of selection of characteristics which contributes to the fitness of survival of organisms. Genetic variation within a population of organisms may cause some individuals to survive and reproduce more successfully than other Biology 286: Introduction to Ecology and Evolution Thought/Review Questions: Spring 2018 WEEK 4: 1. Generally, for any trait to be selected for, what has to be true about the benefits of the trait relative to the costs of the trait? Selection favors heritable traits for which the benefits (b) outweigh the costs (c) 2. What is altruism? Why have some species evolved the behavior of sacrificing individual survivorship for reproduction? Altruism: behavior by an individual that increases the fitness of another individual while decreasing the fitness of the actor If helpers are helping relatives then they help get shared genes into the next generation. 3. What are stimulus response behaviors and why are they important? Stimulus response behavior: a specific behavior that is elicited by a specific stimulus Stimulus-response behaviors are highly stereotyped (invariant) 4. Why can behavioral traits be both plastic and heritable? Behavioral plasticity is itself an adaptation 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. ---Behavioral plasticity is itself an adaptation. The relative contributions of the environment and genetics in behavior can be measured as heritability Example: --- Drosophila pseudoobscura mating duration ---Copulation duration is a heritable AND plastic trait ---Plasticity: Males mate for a LONGER time in the presence of a rival male by about 80 seconds, but populations differ in this plasticity ---Heritability: ---mating duration in the absence of a rival male = 7.8% ---Mating duration in the presence of a rival male = 12% ---In D. melanogaster father-son heritability of mating duration is even more heritable: 23 – 46% 5. What sensory modalities may be involved in communication? Communication uses different signals. ---Visual, auditory, olfactory, or tactile signals are common. ---Example: Alarm calls of chickadees can warn about the presence of a raptor and communicate potential threat (e.g., raptor size). ---Receivers of signal have auditory systems tuned to different signal frequencies 6. What is sexual dimorphism? Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in many animals and some plants. Differences may include secondary sex characteristics, size, color, markings, and may also include behavioral differences. 7. Compare the different investments males and females make in reproduction, on average. Female has less gametes and they are more costly to produce that male gametes Women can produce only a limited number of offspring, whereas a man can potentially father an unlimited number The female carries the offspring inside her, whereas a male can simply walk away 8. What is sexual selection and what is its relationship to natural selection? Sexual selection: selection on traits associated with mating success Interactions between Sexual and Natural Selection ---Balance hypothesis ---Male traits are exaggerated by female choice until their overall fitness cost is too high. ---Example of the evolutionary trade-off ---“Truth in advertising” hypothesis ---Elaborate phenotypic traits of males are an indicator of overall fitness. ---Help females choose a superior male, thereby increasing the quality of the progeny. 9. According to Bateman’s principle, which sex experiences more intense sexual selection, and why? Bateman's principle, in evolutionary biology, is that in most species, variability in reproductive success (or reproductive variance) is greater in males than in females. Bateman suggested that, since males are capable of producing millions of sperm cells with little effort, while females invest much higher levels of energy in order to nurture a relatively small number of eggs, the female plays a significantly larger role in their offspring's reproductive success. Bateman’s paradigm thus views females as the limiting factor of parental investment, over which males will compete in order to copulate successfully. 10. We discussed several mating systems (monogamy, serial monogamy, polygyny, polyandry). Be able to describe each of these and how ecological factors have shaped them. Monogamy: males mate with a single female. Serial monogamy: monogamic relationship lasts for a single breeding season. Polygyny: each male mates with more than one female during a breeding season. Polyandry: each female mates with more than one male during a breeding season. 11. What is a lek? What is a harem? In mating systems which have these, how are Nc and Ne affected? Lek: communal area in which two or more males of a species perform courtship displays. In this mating system the males only contribute genes; they don’t raise the children. Males are mating with more than one female (polygyny). Harem: a group of females a male defends from other males and has exclusive access; Harem polygyny is a mating system where an individual males monopolizes access to groups of females either by defending a resource that the females require, or by directly preventing other males from mating with those females. Ne = effective population size Nc= census population size Ne is lower than Nc because mating is less random, fewer males are contributing to the next generation, and more females are mating. 12. What are at least three costs and three benefits to being social? Benefits