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17 Cards in this Set
- Front
- Back
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microevolution
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evolutionary change below the species level; change in the allele frequencies in a population over generations
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genetic variation
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differences among individuals in the composition of their genes or other DNA segments
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average heterozygosity
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the percentage, on average, of a population's loci that are heterozygous in members of the population
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geographic variation
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difference between the gene pools of geographically separate populations or population subgroups
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population
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a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring
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gene pool
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aggregate of all copies of every type of allele at all loci in every individual in a population. the term is also used in a more restricted sense as the aggregate of alleles for just one or a few loci in a population
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Hardy-Weinberg princiiple
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the principle that frequencies of alleles and genotypes in a population remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work
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genetic drift
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a process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. effects of genetic drift are most pronounced in small populations
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founder effect
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genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population
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bottleneck effect
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genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population
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gene flow
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the transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes
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relative 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 in the population
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directional selection
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natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals
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disruptive selection
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natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes
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stabilizing selection
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natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes
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heterozygote advantage
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greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool
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frequent-dependent selection
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selection in which the fitness of a phenotype depends on how common the phenotype is in a population
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