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27 Cards in this Set
- Front
- Back
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4 principles
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Mutation, Natural Selection, Genetic Drift, Gene Flow
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What is the only source of genetic variation that occurs all the time?
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Mutation (Changes in DNA sequence)
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Is mutation a slow and weak evolutionary force?
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Yes
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What force of evolution is non-random & erodes variation (decreases it within pops. but increases it among them)?
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Natural Selection
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What are the prerequisites for natural selection?
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1. variation 2. heritability 3.differential reproduction (reproduction w/ enviros. as selective pressures) |
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What are that factors affecting evolution by natural selection?
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1. strength of assosciation btwn. variation & reproductive differences 2. heritability 3.generation time |
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Why isn't there perfection?
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1. Perfection takes too much energy (natural selection favors bare minimum) 2.Evolution is random 3. Selection can't make traits, only choose them |
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Directional selection
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Favors one extreme phenotype
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Stabilizing/Balanced selection
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Favors intermediate phenotypes
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Disruptive selection
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Favors both extremes & results in bimodial distribution
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Intersexual selection
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Mate choice/underlying genetic fitness
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Intrasexual selection
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Males competing for female attention
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Define genetic drift
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1. random change in allele/trait frequencies 2. think random event in enviro. influences gene pool |
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Is genetic drift more impactful in large or small populations?
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Small-- can lead to fixation (every pop. member has variant of same trait)
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Define founder effect.
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Parent pop. moves to new area & offspring less variant
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Define bottleneck effect.
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Former pop. killed off so less variation & then that smaller one reproduces so back to same size but less variation.
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Define gene flow.
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Movement of genes between populations.
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Gene flows causes admixture. Define admixture.
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Sharing of genes amongst populations.
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Gene flow increases variation within populations
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It decreases variation amongst populations.
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On what does natural selection operate?
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The phenotype & gametes. The phenotype usually interacts w/ the enviro.
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What is Ernst Mayr's biological species concept?
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Groups of interbreeding populations can be reproductively isolated from other such groups.
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What are some examples of premating isolation mechanisms?
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Habitat isolation, Temporal isolation (nocturnal), Behavioral isolation, Mechanical incompatibility
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What are some examples of postmating isolation mechanisms?
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Sperm/egg incompatibility, zygote inviability, Embryo inviability, Offspring sterility
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Define anagenisis
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Evolution of one species into another
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Define cladogenisis
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Evolution via branching of species
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Define allopatric speciation
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Speciation via geographic isolation
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Define sympatric speciaiton
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Speciation occurring in the same location
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