Glossary Definition
bottleneck
An event in which a population's size is greatly reduced. When this happens, genetic drift may have a substantial effect on the population. In other words, when the population size is radically reduced, gene frequencies in the population are likely to change just by random chance and many genes may be lost from the population, reducing the population's genetic variation. For a more detailed explanation, see our resource on bottlenecks in Evolution 101.

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