Figure 3.

For the density-dependent analog of the model described by Eq. 1, we replace the survival probabilities S_i(t) by the Ricker functions: S₁(t) = r₁(t)me^−fmN(t) with r₁ = S_a with probability p and r₁ = S_b with probability 1 − p, and S₂(t) = S_cme^{−(1−f)mN(t)}. In the figure, the population densities are shown as averaged over time. The population becomes extinct when all offspring are allocated to only one habitat, but when offspring are distributed over the two habitats, population persistence becomes feasible. Parameters used are as in Fig. 2, m = 100.