Appendix 3—figure 16. The non-Lande case: A comparison of the linear and nonlinear approximations for the expected change in fixation probability of alleles segregating at the time of the shift.

The simulation results were generated using the single allele simulation, as described in Section 2.1; errors are often not visible because they are smaller than the points. The analytic predictions were based on the linear non-Lande (Equations A3-60 and A3-70) and nonlinear non-Lande (Equations A3-60, A3-88 and A3-89) approximations averaged over the initial MAF distribution (Equation A3-27) with the corresponding parameters. The nonlinear approximation performs better than the linear one for intermediate effect alleles when polygenicity is low (see the gold shaded regions in A and B). As in Appendix 3—figure 13, we normalize the changes in fixation probability by $\mathrm{\Lambda }/V_A(0)$ to make them comparable for different initial variances and shift sizes (Equation A3-61).