| A | B |
|---|
| average heterozygosity | percent of a population’s loci that are heterozygous in members of the population |
| balanced polymorphism | ability of natural selection to maintain diversity in a population |
| balancing selection | maintains stable frequencies of two or more phenotypic forms in a population |
| bottleneck effect | after a natural disaster surviving population is no longer genetically representative of the original population. |
| cline | graded variation in a trait that parallels a gradient in the environment |
| directional selection | favors individuals at one end of the phenotypic range |
| disruptive selection | favors individuals on both extremes of a phenotypic range over intermediate phenotypes |
| fitness | contribution an individual makes to the next generation |
| founder effect | isolated individuals are no longer representative of the original population’s gene pool |
| frequency-dependent selection | decline in the reproductive success from the phenotype being too common in a population |
| gene flow | additions to or subtractions from a population resulting from the movement of fertile individuals |
| gene pool | total aggregate of genes in a population at any one time |
| genetic drift | fluctuations in allele frequencies from one generation to the next because of a population’s finite sin small gene pools |
| genetic polymorphism | existence of two or more distinct alleles at a given locus in a population’s gene pool |
| geographic variation | differences between the gene pools of separate populations |
| Hardy-Weinberg equilibrium | condition describing a non-evolving population |
| Hardy-Weinberg theorem | frequencies of alleles and genotypes in a population remain constant from generation to generation |
| heterozygote advantage | heterozygotes have greater reproductive success compared to homozygotes |
| intersexual selection | individuals of one sex (are choosy in selecting their mates from individuals of the other sex |
| intrasexual selection | direct competition among individuals of one sex for mates of the opposite sex |
| microevolution | change below the species level |
| modern synthesis | comprehensive theory of evolution including genetics |
| mutation | change in the DNA of a gene |
| neutral variation | diversity that confers no apparent selective advantage. |
| phenotypic polymorphism | existence of two or more distinct forms in a population |
| polymorphism | coexistence of two or more distinct forms in the same population |
| population | localized group of individuals that belong to the same biological species |
| population genetics | study of how populations change genetically over time |
| pseudogene | DNA segment very similar to a real gene but which does not yield a functional product |
| relative fitness | contribution of one genotype to the next generation compared to that of alternative genotypes |
| sexual dimorphism | distinction between the secondary sex characteristics of males and females |
| stabilizing selection | favors intermediate variants by acting against extreme phenotypes |
