Evolution of the mutation rate at a heterotic locus.

A diffusion model of the modification of mutation rates at a heterotic locus in a finite population is examined. An asymptotic analysis assuming strong selection and weak linkage shows that selection can operate on mutation rates in this setting. There exists a favored mutation rate which is a function only of the equilibrium allele frequency of the heterotic locus and the population size. It is independent of the strength of selection at the heterotoxic locus. Computer simulations are also provided to show that this form of natural selection can occur.