The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. A large gene pool indicates a large genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced fitness and an increased chance of extinction.

When many alleles exist for a given gene or locus, a population is said to be polymorphic with respect to that gene or locus. When no variation exists, it is labelled monomorphic.

See also: genetic drift, small population size, population genetics

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For the guitarist named Gene Pool, see Gene Pool