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14 Cards in this Set

  • Front
  • Back
occurs when chance events influence the frequency of genes (evolutionary change). Also called neutral selection
genetic drift
changes in gene frequency that occur when a few individuals from a parental population colonize new habitats. The change is a result of founding individuals not having a representative sample of the parental population's genes.
founder effect
changes in gene frequency that result when numbers in a population are drastically reduced, and genetic variability is reduced as a result of the population being built up again from relatively few surviving individuals
bottleneck effect
natural selection that occurs when individuals at one phenotypic extreme have an advantage over individuals with more common phenotypes
directional selection
natural selection that occurs when individuals of the most common phenotypes are at a disadvantage. Produces contrasting subpopulations
disruptive selection
natural selection that results in the decline of both extremes in a phenotypic range. Results in a narrowing of the phenotypic range.
stabilizing selection
a group of populations in which genes are actually, or potentially, exchanged through multiple generations. Numerous problems with this definition make it difficult to apply in all circumstances.
the process by which two or more species form from a single ancestral stock
speciation that occurs in populations separated by geographical barriers
allopatric speciation
evolutionary change that results in the formation of a number of new characteristics from an ancestral form, usually in response to the opening of new habitats
adaptive radiation
speciation that occurs in populations that have overlapping ranges
sympatric speciation
groups of individuals of the same species that occupy a given area at the same time and share a common set of genes
differences within a population are based on variety within each trait
the sum of all the alleles for all traits in a sexually reproducing population is a pool of hereditary resources for the entire population
gene pool