Resource subdivision and the advantage of genotypic diversity in Drosophila

It is noted that maintenance of genetic heterogeneity in natural populations of Drosophila, through the effect that variation in genotypic diversity across breeding sites may have on their productivity, depends not only on the effective number of parents contributing gametes to a site, as previously shown by other authors, but also on the number of loci underlying the variation in fitness. Using Monte Carlo simulation, it is found that as the number of loci increases, the effect of resource subdivision on the establishment of an initially rare allele introduced into the population becomes virtually indistinguishable from the pure drift case. It seems unlikely that this mechanism can explain the maintenance of a significant proportion of genetic variation in natural populations of Drosophila, although it may still be important in preserving linked gene complexes such as inversions.