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27 Cards in this Set
- Front
- Back
Natural selection
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the differential reproduction of genotypes; caused by factors in the environment; leads to evolutionary change
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Hardy-Weinberg equilibrium
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mathematical description of the fact that allele and genotype frequencies remain constant in a random-mating population in the absence of inbreeding, selection, or other evolutionary forces
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Gene Flow
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movement of alleles from one population to another
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Assortative mating
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a type of nonrandom mating in which phenotypically similar individuals mate more frequently
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Disassortative mating
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a type of nonrandom mating in which phenotypically different individuals mate more frequently
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Genetic drift
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random fluctuation in allele frequencies over time by chance
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Founder effect
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the effect by which rare alleles and combinations of alleles may be enhanced in new populations
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Bottleneck effect
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a loss of genetic variability that occurs when a population is reduced drastically in size
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Artificial selection
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change in the genetic structure of populations due to selective breeding by humans
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Fitness
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the genetic contribution of an individual to succeeding generations
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Frequency-dependent selection
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a type of selection that depends on how frequently or infrequently a phenotype occurs in the population
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Oscillating selection
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the situation in which selection alternately favors one phenotype at one time, and a different phenotype at another time, for example, during drought conditions versus during wet conditions
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Heterozygote advantage
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the situation in which individuals heterozygous fora trait have a selective advantage over those who are homozygous; example- sickle cell anemia
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Disruptive selection
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a form of selection in which selection acts to eliminate rather than favor the intermediate type
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Directional selection
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a form of selection in which selection acts to eliminate one extreme from an array of phenotypes
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Stabilizing selection
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a form of selection in which selection acts to eliminate both extremes from a range of phenotypes
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Relative dating
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the determining the relative order of past events, without necessarily determining their absolute age
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Absolute dating
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age of fossils is estimated by rates of radioactive decay
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Homologous structures
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structures with different appearances and functions that all derived from the same body part in a common ancestor
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Vestigial structures
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a morphological feature that has no apparent current function and is thought to be an evolutionary relic; example: hip bones in boa constrictors
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Convergent evolution
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the independent development of similar structures in organisms that are not directly related
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Genotype
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the genetic makeup of an organism
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Phenotype
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the visible expression of a gene, the observable characteristics of an individual
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Allele
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one of two alternative states of a gene
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Species
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a kind of organism; designated by binomial names written in italics
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Negative frequency-dependent selection
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rare phenotypes are favored by selection; maintains variation
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Positive frequency-dependent selection
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common phenotypes are favored; variation is eliminated from the population
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