Figure 4.
Male ornament divergence in two allopatric populations subject to different selection pressures. Selection on female preference is set to be 20% weaker in population 2, both for the individual cost of choice and epistasis in the joint cost of choice (population 1 b = 1.0, θ = 0.6; population 2 b = 0.8, θ = 0.48). Otherwise selection in the two populations is identical. There are two male ornaments, so there are four possible character states: gray, t̄1 < 0, t̄2 < 0; stipple, t̄1 > 0, t̄2 < 0; blank, t̄1 > 0, t̄2 > 0; and stripe, t̄1 < 0, t̄2 > 0. The sequence in which these character states evolve is shown through time. The two populations start with the same strength of preferences and ornament sizes. Other parameter values as in Fig. 2.