Selection on recombination in subdivided populations with stabilizing selection

Abstract

This paper presents the results of simulation runs of a discrete three‐locus model. Optimizing selection acts on two of those loci. The third locus is a recombination modifier which is closely linked to the other two loci and determines their recombination rate, The population is subdivided (stepping‐stone model) and exposed to three different environments. Three populations were analyzed differing in the spatial pattern. The results are as follows. The spatial pattern of the population and the interactions between natural selection and migration determine the fate of the modifier gene. Close linkage is mainly favored or recombination is neutral. When selection is very weak and there is substantial migration, the frequency of the recombination‐reducing allele decreases. This decrease, however, is very small. It is questionable that this small decrease indicates selection for increased recombination in this model. The characteristic length is not a precise measurement for predicting the fate of a recombination modifier gene.