Figure 3.

Effect of varying the strength of selection on the population mean fitness. Mean fitness is shown as a function of α (the proportion of demes with type 1 environment), for s₁=0.0005, s₂=0.005 (filled circles, solid line), s₁=0.001, s₂=0.01 (filled squares, dashed line) and s₁=0.005, s₂=0.05 (empty squares, dotted line). Other parameters are as in Figure 1, with m=0.01; selection is soft.