Frequency-dependent selection, beneficial mutations, and the evolution of sex.

This paper presents a mathematical model of a population in which multiple alleles at a particular locus are maintained by frequency-dependent selection. The results suggest that, if the population reproduces sexually, the benefit conferred on the population by beneficial mutations at other loci will typically be much larger than if the population reproduces by asexual means. In part, this is true because, in asexual populations, beneficial mutations can produce suboptimal distributions of the alleles that are subject to frequency-dependent selection. Another factor that produces an advantage for sex is that, in asexual populations, beneficial mutations that have achieved a high copy number may nevertheless be lost from the population. This is highly unlikely in sexual populations.