Two linked loci under mutation-selection balance and Muller’s ratchet

• Mutation-selection balance at two linked loci can be fully investigated. Dynamics of loss wild-type alleles depend on the type epistasis. After Muller's ratchet clicks, a deleterious allele is fixed by selection. We report complete analysis deterministic model mutations and negative selection against them haploid without recombination. As long as mutation weaker force than selection, mutant remain rare only stable equilibrium, otherwise, variety dynamics are possible. If mutation-free genotype absent, generally equilibrium one that corresponds to fixation locus where it less deleterious. This suggests follows click governed natural instead random drift.