Fixation of a female-specific, infertility-causing mutation when the mating matrix is shifted from age indifferent preference model (AP) to male preference for younger females model (YF) at time period 1000.

The locus is assumed to have an age of onset at age class 6 (30–35 years). Fixed population size (N), mutation rate (μ) and selection strength (e) for four different simulations (each repeated 100 times) are indicated in the figure. Y-axis is average frequency of the mutant allele in the female population. Curves: 1) N = 1000, μ = 0.005, e = 0.025; 2) N = 1000, μ = 0.005, e = 0.075; 3) N = 1000, μ = 0.001, e = 0.025; 4) N = 250, μ = 0.001, e = 0.025. The inset shows the effect of the strength of selection (e) on female fertility probability (probability if mated to produce an offspring) for a homozygous mutant female.