Term
| what method study do evolutionary biologist use? |
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Definition
| Hypothetico-deductive method- gather evidence, form theory, test theory, reform theory, retest theory. |
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Term
| what are proximate questions? ultimate questions? |
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Definition
| proximate- "how?" questions, ultimate- "why?" questions (how come, what for) |
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Term
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Definition
- HIV, AIDS
-contains RNA, rather than DNA
- copies its RNA into DNA
- uses reverse transcriptase |
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Term
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Definition
-virion encounters host cell
-binds protein called CD4
-injects replication machinery ( RNA, reverse transcriptase, integrase, and protease
- Attacks helper T cells |
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Term
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Definition
-recognize and kill infected T cells
- stimulate B cells to secrete antibodies- kill free virus particles
- Supply of T cells is finite |
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Term
| why does HIV evolve so rapidly? |
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Definition
- high mutation rate
- short generation time, extremely large pop size |
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Term
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Definition
| evolution of similar traits in closely related species in response to the same selective agent |
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Term
| two common characterisics to greek origins of life |
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Definition
- resulted from generative powers of nature (not actions of god
- they were nonteleological (no underlying design or goal) |
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Term
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Definition
-all species are fixed and eternal
- "eidos" - there is a perfect form
- Scala naturae- linear progression of simple to more complex organisms |
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Term
| Key ideas in how evolutionary thinking developed |
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Definition
- deep time
- rudimentary understanding of biological inheritance
- basic understanding of ecology
- scientific revolution (astronomy, geology, physics, math, chem, bio)
-discover or new faunas
- extinction
- microscope |
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Term
| Which does not result in allele frequency change? |
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Definition
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Term
| A species effective population size will be affected by: |
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Definition
| -All of the above; pop bottlenecks, biased sex ratios, age structures, variance in family size |
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Term
| Narrow-sense heritability estimates the proportion of the total phenotypic variance |
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Definition
| Determined by the ADDITIVE GENETIC VARIANCE |
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Term
| Muller's ratchet predicts that |
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Definition
| asexual species experience higher rates of extinction than sexual species |
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Term
| A form of evolution in which distantly related species evolve similar traits by different genetic mechanisms is called |
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Definition
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Term
| Natural selection always acts to maximize |
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Definition
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Term
| Deleterious mutations are maintained at mutation-selection balance by the action of |
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Definition
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Term
| the two processes that distinguish sexual from asexual reproduction are |
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Definition
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Term
| Linkage disequilibrium is formed in natural populations by the process of |
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Definition
| all of the above; epistatic natural selection, random genetic drift, and gene flow |
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Term
| Coadapted gene complexes may evolve following which type of mutation? |
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Definition
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Term
| which teaching of Aristotle was responsible for preventing the development of a theory of evolution |
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Definition
| that the variation present among individuals is not real or important |
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Term
| The balanced polymorphism involving the right- and left- mouthed forms of the scale-eating fish is an example of: |
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Definition
| frequency-dependent selection |
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Term
| the evolutionary theories of Darwin and Lamarck are similar in proposing that |
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Definition
| an ever-changing world drives biological evolution |
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Term
| the form of selection acting on a quantitative trait in which individuals with intermediate values have the highest fitness is called |
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Definition
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Term
| In a closed population not experiencing gene flow, random genetic drift will always result in the |
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Definition
| loss or fixation of neutral alleles |
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Term
| the most common form of selection acting at the genic level is |
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Definition
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Term
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Definition
All of the above; cannot plan for future events
-acts to favor individuals, not the good |
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Term
| Mutuations that disrupt the proper reading frame in protein-coding sequences are called |
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Definition
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Term
| which of the following is not an assumption of Hardy-Weinberg equilibrium |
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Definition
| there is nonrandom mating |
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Term
| Character displacement occurs when a trait possessed by two species |
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Definition
| Exhibits a greater degree of divergence in SYMPATRY THAN IN ALLOPATRY |
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Term
| What is the red queen hypothesis |
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Definition
| States that its necessary for species to continuously evolve in order to maintain their place in nature. Evolutionary arms race results in adaptations and counter-adaptations |
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Term
| what two processes contribute to the operation of Muller's Ratchet? |
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Definition
| operates through combined action of mutation (introducing mildly deleterious alleles into the population) and RANDOM GENETIC DRIFT that causes the least mutated class to be lost by chance |
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Term
| Muller's ratchet: how does sexual reprodcution "break" muller's ratchet? |
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Definition
| sex breaks the ratchet because recombination can "recreate" individuals having the lowest numbers of deleterious alleles in the population |
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Term
| why do pops rapidly lose neutral genetic variation when they experience bottlenecks? |
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Definition
| because the rate of random genetic drift increases significantly when the pop size becomes very small. the number of Gens spent at low Ne will largely determine how much neutral variation is lost |
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Term
| why do pops lose adaptively important genetic variation when they experience a bottleneck? |
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Definition
| the strength of selection(s) acting on selected alleles is overwhelmed by the stochastic changes in frequencies caused by random drift. this happens hen the product of Ne x s falls below 1 |
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Term
| example of pop bottleneck |
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Definition
| cheetahs; levels of genetic variation detected at the allozyme level are extremely low |
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Term
| how do discrete traits differ from quantitative traits |
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Definition
1. discrete traits are determined by small numbers of loci (usually one)
2. for discrete traits it is possible to assign phenotypes into easily identified and distinct categories |
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Term
| what determines how effectively a quantitative trait will respond to directional selection? |
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Definition
1. magnitude of trait's narrow-sense heritability
2. intensity of selection acting on the trait-estimated either as the selection differential or the selection gradient. |
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Term
| what is the comparative method? |
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Definition
-used to test adaptive hypotheses, 3 steps
1. observe/ describe some trait
2. formulate an adaptive hypothesis for the evolution of the trait
3. test the hypothesis by undertaking comparisons among indys of a species, or among species |
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Term
| what is a multi-gene family? |
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Definition
-cluster of tightly linked genes on chromosome that originated from single ancestral gene by process of gene duplication.
-duplicated copies have acquired new functions |
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Term
| how are multi-gene families formed? |
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Definition
| formed by unequal cross over events that lead to gene duplications. |
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Term
| Example of multi-gene family |
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Definition
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Term
| 3 explanations how a trait isn't an adaptation |
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Definition
-trait evolved by random genetic drift
- trait evolved because it was correlated with another that was the direct target of selection
- evolved by sexual selection |
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Term
| what conditions necessary for natural selectino to overpower the homogenizing effect of gene flow? |
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Definition
| -when the strength of selection (s) exceeds the rate of gene flow (m) |
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Term
| Linkage disequilibrium decays in natural pops by process of |
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Definition
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Term
| which of the following is not a form balancing selection |
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Definition
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Term
| neutral theory of molecular evolution predicts that |
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Definition
all of the above;
-proteins subject to weak selective contraints will evolve at rapid rates
-the rate of protein evolution is roughly constant per site per year
- the rate of neutral evolution is independent of population size
-the majority of protein polymorphisms in natural populations are neutral |
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Term
| Broad-sense heritability estimates the proportion of the total phenotypic variance |
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Definition
| -determined by the total genetic variance |
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Term
| Evolutionary theories of Darwin and Lamarck are similar in that |
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Definition
| evolutionary chance occurs gradually |
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Term
| character displacement occurs when a trait possessed by two species |
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Definition
| exhibits a greater degree of divergence in sympatry than in allopatry |
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Term
| co-adapted gene complexes commonly evolve following which type of mutation |
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Definition
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Term
| the form of phenotypic selection in which individuals with extreme values of a trait have the highest fitness is called |
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Definition
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Term
| If a species fluctuates in abundance over time, its effective pop size equals |
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Definition
| the harmonic mean of the actual pop numbers |
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Term
| gene flow will typically result in the |
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Definition
| - elimination of genetic differences among natural pops |
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Term
| red queen hypothesis predicts that |
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Definition
| asexual species experience higher rates of extinction than sexual species |
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Term
| Muller's ratchet predicts that asexual pops will |
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Definition
| accumulate deleterious mutations faster than sexual pops |
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Term
| deleterious mutations are maintained at mutation-selection balance by the action of |
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Definition
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Term
| what are two characteristics distinguishing quantitative traits from "discrete traits" ? |
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Definition
1. quantitative characters exhibit continuous variation among phenotypes in the population
2. quantitative characters are controlled by many loci |
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Term
| example of a quantitative trait |
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Definition
| height or IQ scores in humans |
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Term
| example of discrete trait |
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Definition
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Term
| how does knowing heritability of a trait allow us to predict its response to selection |
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Definition
| -knowing the heritability (h^2) allows us to predict the response to selection (R) if we know the strength of selection (S) from the equation R=h^2(S) |
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Term
| what is linkage disequilibrium |
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Definition
| the nonrandom association of genotypes at two (or more) loci. In other words, it occurs when the genotypes at one locus do not occur independently of those at a second locus |
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Term
| what processes create linkage disequilibrium? which is most important? |
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Definition
-natural selection (most important)
-random genetic drift
-population admixture |
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Term
| what is the two-fold cost of sex? |
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Definition
| refers to the fact that an asexual female has effectively twice the fitness as a sexual female (since she doesn't "waste" the effort of producing males). As a result, sexual reproduction will be quickly eliminated from a population seeded with an asexual female |
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Term
| why are asexual species expected to experience lower rates of adaptive evolution than sexual species |
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Definition
| experience lower rates because advantageous mutation must accumulate in the same lineage over time. Since advantageous mutations are rare, this will occur much more slowly than in that of a sexual pop. |
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Term
| according to neutral theory of molecular evolution, what determines how rapidly a protein evolves over evolutionary time? |
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Definition
-degree of selective constraint acting at protein determines rate of Neutral evolution. Highly constrained proteins = low neutral mutation rates, and thus evolve slowly.
-less constrained proteins = high neutral mutation rates, and thus evolve quickly |
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Term
| why is the rate of neutral evolution unaffected by pop size? |
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Definition
| b/c it is a function of the rate at which neutral alleles enter pops (2Nu) times the probability that these mutations will be fixed (1/2N). pop size cancels out- the rate = 2Nu x 1/2 N= u |
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Term
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Definition
| RF quantifies the number of gene copies a phenotype or genetype contributes to the next generation relative to the other phenotypes |
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Term
| What determines the magnitude of gene flow among pops? |
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Definition
| the parameter "m", which is the proportion of individuals (or genes) that enter a pop from a different pop |
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Term
| why's it necessary to "correct" for phylogenetic history ? |
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Definition
| b/c the data may not be independent of one another. This means that the trait may be found in a group of species because it was inherited from a common ancestor rather than having evolved independently in each group |
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Term
| 3 approaches to studying natural selection in the wild |
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Definition
- testing for correlations between traits that vary geographically and environmental factors (presumably causing traits to vary)
- comparisons between closely related sympatric species. This is usually done to detect character displacement.
-comparisons between species living in similar habitats. this approach is used to detect either convergent evolution (if the species are very distantly related) or parallel evo (if the species are closely related. |
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Term
| Hardy-weinberg assumptions |
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Definition
-huge pop size
-no mutation
- random mating
- no selection
- no migration |
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