| A | B |
|---|
| gene pool | combined genetic information of all members of a particular population |
| population | group of individuals of the same species that live in the same area |
| relative frequency | number of times an allele occurs in a gene pool compared with the number of times other alleles occur |
| single-gene trait | trait controlled by a single trait |
| polygenic trait | trait controlled by two or more genes |
| directional selection | form of natural selection in which the entire curve moves |
| stabilizing selection | form of natural selection by which the center of the curve remains in its current position |
| disruptive selection | form of natural selection in which a single curve splits into two |
| genetic drift | random change in allele frequencies that occurs in small populations |
| founder effect | change in allele frequencies as a result of the migration of a small subgroup of a population |
| Hardy-Weinberg principle | principle that allele frequencies in a population will remain sonstant unless one or more factors cause the frequencies to change |
| genetic equilibrium | situation in which allele frequencies remain constant |
| speciation | formation of new species |
| reproductive isolation | separation of species or populations so that they cannot interbreed and produce fertile offspring |
| behavioral isolation | two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding |
| geographic isolation | two populationsare separated physically by geographic barriers such as rivers, mountains, or water |
| temporal isolation | two populations reproduce at different times |
| directional selection | individuals at one end of the distribution curve have higher fitness than those in the middle or at other end of the curve |
| distribution curve | the way that statistics are grouped on a curve, usually on a bell curve |
| relative frequency | usually expressed as a percentage |
