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Chapter 11
Term | Definition |
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Gene pool | The total set of genes, including all alleles, that are present in a population at any one point in time |
Allele frequency | Proportion of one allele, compared with all the alleles for that trait, in the gene pool |
Normal distribution | A distribution of numerical data whose graph forms a bell-shaped curve that is symmetrical about the mean |
Microevolution | Observable change in the allele frequencies of a population over a few generations |
Directional selection | A natural selection process in which one genetic variation is selected and that causes a change in the overall genetic composition of the population |
Stabilizing selection | A type of natural selection in which the average form of a trait is favored and becomes more common |
Disruptive selection | A type of natural selection in which two extreme forms of a trait are selected |
Gene flow | The movement of genes into or out of a population due to interbreeding |
Genetic drift | The random change in allele frequency in a population |
Bottleneck effect | Genetic drift that results from an event that drastically reduces the size of a population |
Founder effect | Genetic drift that occurs after a small number of individuals colonize a new area |
Sexual selection | An evolutionary mechanism by which traits that increase the ability of individuals to attract or acquire mates appear with increasing frequency in a population; selection in which a mate is chosen on the basis of a particular trait or traits |
Hardy-Weinberg equilibrium | Condition in which a population's allele frequencies for a given trait do not change from generation to generation |
Reproductive isolation | A state in which a particular set of populations can no longer interbreed to produce future generations of offspring |
Speciation | The formation of new species as a result of evolution |
Behavioral isolation | Isolation between populations due to differences in courtship or mating behavior |
Geographic isolation | Isolation between populations due to physical barriers |
Temporal isolation | Isolation between populations due to barriers related to time, such as differences in mating periods or differences in the time of day that individuals are most active |
Convergent evolution | The process by which unrelated species become more similar as they adapt to the same kind of environment |
Divergent evolution | Evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions |
Coevolution | The evolution of two or more species that is due to mutual influence often in a way that makes the relationship more mutually beneficial |
Extinction | The death of every member of a species |
Punctuated equilibrium | A model of evolution in which short periods of drastic change in species, including mass extinctions and rapid speciation, are separated by long periods of little or no change |
Adaptive radiation | An evolutionary pattern in which many species evolve from a single ancestral species |