Figure 3.

The average mutant fixation probability as a function of the standard deviation of the bimodal fitness distribution (N = 8) for different average fitness values of the mutants, with 〈r〉 = 1 and $\sigma =\tilde{\sigma }(\mathrm{e}\mathrm{q}\mathrm{u}\mathrm{a}\mathrm{l}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{a}\mathrm{r}\mathrm{d}$ $\mathrm{d}\mathrm{e}\mathrm{v}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{s}),\mathrm{i}\mathrm{n}\mathrm{a}\mathrm{d}\mathrm{e}\mathrm{a}\mathrm{t}\mathrm{h}-\mathrm{birth}\mathrm{Moran}\mathrm{process}$. Normally, a neutral mutant will have 〈P _N〉 = 1/N = 0.125 (dashed horizontal line). Mutants with the mean fitness less than that of the wild type behave as if they are advantageous.