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Biology Ch. 16
Term | Definition |
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Population genetics | The study of the frequency and interaction of alleles and genes in populations |
Microevolution | A change in the collective genetic material of a population |
Bell curve | A symmetrical frequency curve |
Gene pool | All of the genes of the reproductively active members of a population |
Allele frequency | The proportion of gene copies in a population that are a given allele, expressed as a percentage |
Phenotype frequency | The ratio of individuals with a particular phenotype to the total number of individuals in a population |
Hardy-Weinberg genetic equilibrium | The principle that states that the frequency of alleles in a population does not change unless evolutionary forces act on the population |
Immigration | The movement of individuals into a population |
Emigration | The movement of individuals out of a population |
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 |
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 |
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 |
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 |
Speciation | The formation of new species as a result of evolution |
Morphology | The study of the structure and form of an organism |
Biological species concept | The principle that defines a species as a group of organisms whose members can interbreed to produce offspring |
Geographic isolation | The physical separation of populations due to geographic barriers that prevent interbreeding |
Allopatric speciation | Happens when species arise as a result of geographic isolation |
Reproductive isolation | The inability of members of a population to successfully interbreed with members of another population of the same or a related species |
Prezygotic isolation | "Premating isolation" occurs before fertilization |
Postzygotic isolation | "Postmating isolation" occurs after fertilization |
Sympatric speciation | When two subpopulations become reproductively isolated within the same geographic area |
Gradualism | A model of evolution in which gradual change over a long period of time leads to biological diversity |
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 |