Figure 1

Computer simulations of adoption of advantageous mutations. (a) Computer simulation showing adoption of advantageous mutations at a single diploid locus. The starting populations are sexual (blue) and clonal (red); (population size, N = 1500; host mutation rate, μ _h , = 10^-4 bits/allele/generation). Each starting population is uniformly homozygotic and maladapted by one bit per allele (starting adaptation of 0.9375). The parasite environment is uniform and fixed for the duration of the simulation (that is, mutation rate, μ _p , = 0). The sexual population shows a single sweep to full adaptation following adoption of an advantageous mutation, whereas the clonal population proceeds through two sweeps, reflecting the need for adoption of two mutations to proceed to full homozygous matching of the parasite. The target size for the second mutation in the clonal heterozygote is half that for the first mutation, halving the rate of adoption. This is the basic result shown by Kirkpatrick and Jenkins [8]. (b) Distribution of times (in generations) to adoption of advantageous mutation, plotted on lognormal abscissa. Means and standard deviations in this simulation are: 5.35 ± 0.54 (red) (210.7 generations); 5.39 ± 0.53 (blue) (220.0 generations); 6.35 ± 0.45 (575.2 generations).