Mutation rate evolution in partially selfing and partially asexual organisms

Different factors may influence the evolution of the mutation rate of a species: costs associated with DNA replication fidelity, indirect selection caused by the mutations produced (that should generally favor lower mutation rates, given that most mutations affecting fitness are deleterious) and genetic drift, that may render selection acting on weak mutators inefficient. In this paper, we use a two-locus model to compute the strength of indirect selection acting on a modifier locus that affects the mutation rate towards a deleterious allele at a second, linked locus, in a population undergoing partial selfing or partial clonality. The results show that uniparental reproduction increases the effect of indirect selection for lower mutation rates. Extrapolating to the case of a whole genome with many deleterious alleles and introducing a direct cost a DNA replication fidelity, the results can be used to compute the evolutionarily stable mutation rate U. In the absence of mutational bias t...