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16.1, 2, 3

immigration the movement of an individual or a group to a new community or region
emigration the movement of an individual or group out of its native area
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 or 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 individuals with either extreme variation of a trait have greater fitness than individuals with the average form of the trait
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
microevolution evolution at the genetic level
population genetics the study of the frequency and interaction or alleles and genes in populations
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 is equal to the number of individuals with a particular phenotype divided by the total number of individuals in the population
Hardy-Weinberg genetic equilibrium a principle based on a set of assumptions about an ideal hypothetical population that is not evolving
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 related species
prezygotic isolation type of reproductive isolation; occurs before fertilization
postzygotic isolation type of reproductive isolation; occurs after fertilization
sympatric speciation occurs when 2 subpopulations become reproductively isolated within the same geographical area
gradualism a model or 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 extinction and rapid speciation, are separated by long periods of little or no change
Created by: ChambersA20