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Chapter 11

The Evolution of Populations

TermDefinition
gene pool the combined alleles of all of the individuals in a population
allele frequency a measure of how common a certain allele is in the population
normal distribution type of distribution in which the frequency is highest near the mean value and decreases toward each extreme end of the range
microevolution the observable change in the allele frequencies of a population over time
directional selection type of selection that favors phenotypes at one extreme of a trait's range
stabilizing selection type of selection where the intermediate phenotype is favored and becomes more common in the population
disruptive selection type of selection that occurs when both extreme phenotypes are favored while individuals with intermediate phenotypes are selected against
gene flow the movement of alleles from one population to another
genetic drift a change in allele frequencies that causes a loss of genetic diversity in a population
bottleneck effect genetic drift that occurs after an event greatly reduces the size of a population
founder effect genetic drift that occurs after a small number of individuals colonize a new area
sexual selection occurs when certain traits increase mating success
Hardy-Weinberg equilibrium describes five conditions needed for a population to stay in equilibrium: 1) very large population, 2) no emigration or immigration, 3) no mutations, 4) random mating, 5) no natural selection
reproductive isolation isolation that occurs when member of different populations can no longer mat successfully with one another
speciation the rise of two or more species from one existing species
behavioral isolation isolation caused by difference in courtship or mating behaviors
geographic isolation isolation that involves physical barriers that divide a population into two or more groups
temporal isolation isolation that exists when timing prevents reproduction between populations
convergent evolution evolution toward similar characteristics in unrelated species
divergent evolution when closely related species evolve in different directions
coevolution the process in which two or more species evolve in response to changes in each other
extinction the elimination of a species from Earth
punctuated equilibrium states that episodes of speciation occur suddenly in geologic time and are followed by long periods of little evolutionary changes
adaptive radiation the diversification of one ancestral species into many descendent species
Created by: tuohybio1415