Figure 1.

Recombination rate of a plastic modifier. The recombination rates of individuals with different haploid genotypes are illustrated. Individuals carrying the m allele always have the baseline level of recombination regardless of the alleles they carry at the fitness loci. Individuals carrying the plastic modifier allele M have a recombination rate that depends on their fitness. We assume that w_ab < w_aB < w_Ab < w_AB. In cases M₁ and M₂ (Δr > 0), individuals with low fitness have more recombination than individuals with high fitness (FAR). The FAR modifier causes an incidental increase in recombination on average when w_ref = w_AB (case M₁) but decreases recombination on average when w_ref = w_ab (case M₂). In cases M₃ and M₄ (Δr < 0), individuals with low fitness have less recombination than individuals with high fitness (anti-FAR). The anti-FAR modifier decreases recombination on average when w_ref = w_AB (M₃) but increases recombination on average when w_ref = w_ab (M₄).