key concept 20.5 Multiple Factors Account for the Maintenance of Variation in Populations

Genetic variation is the raw material on which mechanisms of evolution act. But if favored alleles increase in frequency in populations, then why aren’t other alleles always lost from the population? In this section we will discuss several factors—neutral mutations, sexual recombination, frequency-dependent selection, and heterozygote advantage—that affect how genetic variation is established, how it is distributed among individuals, and how it is maintained within populations.

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  • Genetic variation is critical to the survival of a species.

  • Several mechanisms maintain genetic variation in populations despite selection for favored alleles.