David M. Schneider, Ayana B. Martins, Eduardo do Carmo and Marcus A.M. de Aguiar,
Submitted.
We study the evolution of allele frequencies in a large population where random mating is violated in a particular way that is related to recent works on speciation. Specifically, we consider non-random encounters in the haploid phase, which is relevant for organisms that release gametes in the environment so that fertilization is external. The gametes are described by biallelic genes at two loci and pairs of gametes whose alleles differ at both loci are considered incompatible. Evolution under these conditions lead to the complete disappearance of one of the alleles and substantially reduce the diversity of the population. Surprisingly, certain combinations of allele frequencies remain constant during the evolution, revealing the emergence of strong correlation between the two loci promoted by the epistatic mechanism of incompatibility. The allele frequencies at equilibrium depend only on their initial values, and so does the time to equilibration. We discuss the relation between this model of assortative fertilization and selection against double heterozygous individuals and its relevance to speciation in spatially extended populations.
