Parameter values are, FST = 0.5, S0 = 1, f0 = 1, y = 1, αS = 0.1, αf = 0.1. Gray regions indicate positive selection (positive gradient of the fitness surface), white regions negative selection (negative gradient of the fitness surface). Equilibria occur where lines intersect, and stability is indicated by the fact that vertical deviations from this point (i.e., mutants) are negatively selected (occur in white regions). These PIPs are typical: all equilibria in our model are evolutionarily and convergence stable.