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29 Cards in this Set
- Front
- Back
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microevolution
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change in the genetic makeup of a population from genearation to generation
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population genetics
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the study of how populations change genetically over time
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modern synthesis
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a comprehensove theory of evolution that integrated ideas from many other fields
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gene pool
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the aggregate of genes in a population at any one time
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Hardy-Weinberg Theorem
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states that the frequencies of alleles and genotypes in a population's gene pool remain constant from generation to generation
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Mutations
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changes in the nucleotide of DNA
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Gene Duplication
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important source of variation
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Genetic Drift
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alelle frequencies fluctuate unpredictable from one generation to another
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Bottleneck effect
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a sudden change in the enviornment may drastically reduce the size of a population
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founder effect
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when a few individuals become isolated from a larger population this smaller group may establish a new population whose gene pool is not reflective of the source population
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gene flow
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genetic addition to and/or subtractions from a population resulting from the movement of fertile individuals or gametes
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phenotypic polymorphism
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tow or more distinct morphs are each represented in high enough frequencies to be readily noticable
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genetic polymorphisms
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heritable morphisms
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average heterozygosity
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the average percent of these loci that are heterozygous
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geographic variation
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differences between the gene pools of seperate populations or population subgroups
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fitness
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the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
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relative fitness
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the contribution of a genotype to the next generation compared to the contribuitons of alternative genotypes for the same locus
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directional selection
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when a population's enviornment changes or when members of a population migrate to a new habitat with different enviornmental conditions than their former ones
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disruptive selection
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occurs when conditions favor individuals on both extremes of a phenotypic range over individuals with intermediate phenotypes
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stabalizing selection
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acts against extreme phenotypes and favors intermediate variants
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balancing selection
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occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population
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heterzygote advantage
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individuals have greater fitness
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frequency- dependent
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the fitness of any one morph declines if it becomes too common in the population
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neutral variation
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no selective advantage in the untranslated parts of the genome
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pseudogenes
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genes that have become inactivated by mutations , genetic noise is free to accumulate in all parts of the gene
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sexual selection
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natural selection for mating success
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sexual dimorphism
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marked differences between the sexes in secondary sexual characteristics, which are not directly associated with reproduction
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intrasexual selection
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selection within the same sex, is a direct competition among individuals of one sex for mates of the opposite sex
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intersexual selection
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individuals of one sex are choosy in selecting their mates from the other sex
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