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Cap- exam 2
evoultionary bio capstone
| Question | Answer |
|---|---|
| Directional selection | characterized by a linear function fitness increases or decreases steadily of a given trait |
| stabilizing selection | bell shaped fitness function individuals with intermediate values of a trait have the highest fitness |
| disruptive selection | u-shaped fitness function individuals with extreme values have highest fitness-possibles to create multiple species. |
| what selection is most common? | directional and stabilizing |
| example of directional selection | Flower pollination by bees. In alpine sky pilots pollinated by bees. Larger flowers had a higher fitness |
| example of disruptive selection | African finch: small and large beak size from different food sources and those 2 were most favored over middle sized beaks or most extreme beaks. |
| example of stabilizing | The larger a Gall is where flies and wasp eggs are laid there is more room for the flies to fight to survive. |
| What are the effects of these different modes of selection on genetic and phenotypic variation? | makes more phenotypes more popular |
| adaptation | a trait or series of traits that increase the fitness of the individual |
| exaptation (pre-adaptation) | a character that evolves in response to one set of selection forces, but comes to function somewhat differently in response to another selection regime. |
| How did the ear ossicles of the mammalian ear evolve? | 3 bones malleus, incus, and stapes. originated through a tetrapod related to crossopterygian fish. malleus and incus evolved in fossil mammals found in reptiles, amphibians and early mammals. |
| In what context should we interpret the effects of an adaptation and how /when it may have arisen? Experimental examples? | Determine if the trait is responsible for increased fitness. look back into ancestry to see then adaptation developed. Fly wings example: decided on 5 different treatments of mixture of wings and flies. |
| pathogenesis | production of clonal offspring from unfertilized eggs |
| What is frequency dependent selection? Examples? | when selection pressures vary over time as a response to allele frequency fluctuation ex. scale eating fish |
| What is the difference between quantitative and qualitative traits? | quantitative traits are ones that show continuous variation qualitative Discontinuous variation is variation within a population of a characteristic that falls into two or more discrete classes. |
| Under what conditions will sex be of no advantage? Conversely, what are the selective advantages to sex? | consistent stable environments do not need to be sexual selection against certain multi-locus genotypes favor asexual. being sexual allows to adjust to changing environments |
| What is mutation-selection balance? Examples? | describes an equilibrium in the frequency of an allele that occurs because new copies of the allele are created by mutation at exactly the same rate that old copies of the allele are eliminated by natural selection |
| mutation-selection balance examples? | Ex. Spinal muscular atrophy cause by deletion on chrom 5 may be exacerbated by additional mutations on near by genes. Kept in population through new mutations. |
| What are the drawbacks to sex? In other words, what are the relative costs of sex? | sex only advantageous in situations that might create linkage disequilibrium: genetic drift-small populations, selection for/against a particular multi-locus genotypes, pop.mixing |
| What is Muller’s ratchet and how is it proposed to operate? | it is deleterious mutations accumulate in finite asexual populations.the rate of accumulation of deleterious mutations will be product of mutation rate, strength of selection and genetic drift. |
| What processes will counter-act Muller’s ratchet? | sexual reproduction and genetic recombination breaks Muller's ratchet. |
| What is genetic load? Under what type(s) of breeding conditions will it most likely be encountered. | population accumulates mutations through loss of most fit sub-populations. mainly found in asexual populations. |
| How do population size and mutation rate affect the process of Muller’s ratchet? | small populations or less quickly accumulate deleterious mutations, ratchet turns quickly. populations of 1000 or more are effectively buffered from the accumulation of deleterious mutations, ratchet doesn't turn. |
| What is the ‘Red Queen’ hypothesis? | "It takes all the running you can do, to keep in the same place." continuing adaptation is needed in order for a species to maintain its relative fitness amongst the systems being co-evolved with |
| Behavioral adaptation | when a behavioral pattern serves as an adaptation and increases the fitness of those individuals with this behaviora |
| What is an experimental example of a behavioral adaptation? | ex 1. Garter snakes at night go under medium sized rocks for thermoregulation. ex 2. Zonosemata vittigera with wing markings flap wings to scare off predators |
| What was the experimental method of Losos, Warhelt, and Schoener and what did they attempt to show in their experiment with Anolis sagrei? | They introduced lizards with variation in hind leg dimension due to vegetation to islands with different vegetation that don't have lizards. they watched their leg dimension on each island. Proved true. |
| How did Greene et al (1987) determine the adaptive significance of wing markings in the tephritid fly, Zonosemata vittigera? | took the Zonosemata vittigera and a house fly and had alternations in their wings normal, cut and re-glued, or wings switched and glued back on. and looked at death rate or flies in with the jumping spider. |
| What is the importance of having a phylogeny for the understanding of an adaptation? | It is important because then it is possible to see if a trait is from an ancestor or is an adaptation to an environment. |
| What are phylogenetic constraints? What methodologies are useful for sorting out phylogenetic constraints? Example? | Limitations on an organism due to evolution. Create a scatter-plot of what characteristic is being looked at, establish phylogeny, and identify characteristics of ancestral node for groups. |
| What are the four crucial aspects of an experimental design when testing for an adaptation? | 1.inclusion of effective control group 2.all groups must be subject to the same conditions throughout experiment 3. randomization of treatments to avoid bias 4.large sample size to avoid chance occurrences |
| How does heterozygote superiority interact with mutation and selectional forces to maintain an allelic equilibrium in a population? | it allows a lethal allele or other mutation to remain in the population through over dominance. Also, heterozygotes have a higher fitness then homozygotes. when at equilibrium the selective advantage for lethal mutations balanced the disadvantage of homo. |
| What did Lively conclude concerning the interaction of the parasitic trematode worm and its host, the freshwater snail, Potamopyrgus antipodarum with regard to selection for or against sexual and asexual individuals? | he concluded that trematodes were in favor of sexual reproduction by the snails because of linkage disequilibrium and selection favors traits that reduce linkage disequilibrium. |
| What is the relationship between quantitative phenotypic traits and the number of genes (loci) involved in the formation of these traits? | quantitative is usually polygenic: linkage diequilibrium and pleiotropy |
| linkage disequilibrium | a non-random association among alleles at different loci. When you have one allele at locus 1 you have another allele at locus 2 (same of different chrom) |
| pleiotrophy | when one locus (gene) influences multiple traits |
| In what context should we interpret the effects of an adaptation and how /when it may have arisen? Experimental examples?? | look for traits that inc. fitness and test for adaptation significance. ex. long neck giraffes originally though to have long necks for food is really used as a weapon, the longer the neck the thicker the skull. |
| Under what conditions are equal sex ratios beneficial and under what conditions might it be better to produce more female than male offspring? Why? | equal leaves the greatest number of offspring. Then the population needs to grow it is more beneficial to have more women then men. If there is more men then women then there is more competition for men to mate. |
| What is phenotypic plasticity? | the variation in phenotypic characteristics as a sum of the interactions between genotype and environment -the influence of environment conditions on phenotypic expressions |
| What would be the selective advantages to large degrees of phenotypic plasticity? | the degree to which phenotypic characters may vary with environmental conditions has been shown to be hereditary and may be advantageous, more likely to survive the larger the degree. |
| What is a genotype by environment interaction? | ex. water fleas from different lakes behavior is watched. those in lakes with lots of fish are farther down in water to avoid predators. those without are higher, closer to the light. |
| Under what optimality criteria would sex ratios change from the normal 50:50 male:female ratio? Explain. Give an example. | for the optimal criteria for having the most grandchildren have one male and use remaining sources for females. ex. hymenoptera mother determine sex of offspring |
| phenotypic plasticity example | flower size in Begonia involucrata. larger flowers get pollinated more then small ones. Female flowers act as males and grow larger then needed to by pollinated more |
| How do phylogenetic constraints come into play in limiting the development of adaptations? Examples? | The larger the flowers on the Begonia involucrata the less the amount of flowers produced in an inflorescence |
| How do trade-offs and constraints work to affect the rate of or direction of evolution? Give an example. | Trade off: an inescapable compromise between one trait and another constraints: any factor that tends to slow the rate of adaptive evolution or prevent a population from evolving the optimal value. ex.Begonia involucrata |
| What is sexual selection? What is the difference between intra-sexual and inter-sexual selection? | sexual selection: the differences in individual success at getting a mate intrasexual: male-male competition leads to a mate for winner intersexual: females choose mate and not controlled by male control |
| intrasexual selection example | iguanas on Galapagos. females can only mate once so mating competition is high. they keep weight above optimum level |
| Why may it be beneficial to have a genetic predisposition towards phenotypic plasticity in a species? | they would be more likely to adapt to their environment to make themselves more fit. Ex. Ice fish |
| How might local mate competition affect sex ratios? Example? | Local mate competition can cause an inequality in sex ratios. Ex. In Lion populations when a new dominate male comes in and scares away the other males the new lion kills the male lion cubs to reduce a future competition. |
| How do energy allocations constrain or influence the development of adaptations or characteristics? Examples? | Like in the Begonia involucrata when the flowers concentrate their energy on having larger flowers they loose inflorescence. |
| What sorts of sexual dimorphisms might prevail when either intra-sexual or inter-sexual selection is in place? | sexual dimorphism: the difference between the phenotypes of males and females. If males are large then the population with become larger body wise also. Then intersexual selection the males need to impress the females, they have a choice. |
| Why do reproductive strategies often conflict between males and females? | For females they can only mate once where as males want to mate multiple times. |
| How does sexual selection affect speciation? genetic diversity? Behavior (i.e., parental care)? | In different species and families there is a difference in obtaining a mate. This difference affects speciation because they are not compatible. Thus leabing to genetic diversity and behavior differences. Male caretakers doesn't happen often. |
| What is the basis of sexual selection? How might it produce results that would seem contrary to the normal dogma of evolution based on the survival of the fittest? | For intrasexual selection the males tend to be larger then optimum level. Though they do mate with the most when they are the dominent male they die sooner. Also, it leave many males without reproduceing and dying before they can pass their genes on. |
Created by:
anc62
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