Selective advantage of sexual over asexual reproduction (r
= 0, r
= 0, r
= 0.1) (a,c) and of high over low recombination (b,d) in both the standard model (a,b) and the sequential-updating model (c,d), plotted for different selection coefficients (s) and different population sizes. The y-axis corresponds to the selection on the modifier (of sex/recombination), which is measured as the frequency change during a simulation run (i.e. 1000 host generations after introduction of the modifier allele M), averaged over 10000 simulation runs (100 for the deterministic model) with different random initial conditions.