A single locus model of selection in permanent translocation heterozygotes

Abstract

A model for evolution at a single locus in permanent translocation heterozygotes is described. It is also applicable to other permanent structural heterozygotes that possess the mating systems discussed. Recombination occurs between the locus and the chromosomes, which are of two types. The mating system includes selfing and random mating. When recombination is rare, selection will result in almost complete fixation on the single most fit genotype present in a population, regardless of the frequency of selfing. This provides a possible explanation for the ecological success of permanent translocation heterozygotes in some groups of organisms, like Oenothera. It is not necessary to postulate that their success is the result of hybrid vigor. Furthermore, a complete lack of recombination is not necessary for explaining the observed association of alleles with particular segmental arrangements. A small amount of recombination is consistent with the observation that different segmental arrangements often carry different alleles.