Figure 1.

An illustration of the different selection pressures, as the environments change, in the two demes. The environmental states are sampled from the same distribution but independently in the two demes, which leads to a decoupling of the selection pressures experienced by the populations in the two demes. In some generations, selection will favour the same phenotype in both demes, while in others, selection may favour opposite phenotypes. Because the environmental changes are sampled from the same distribution in both demes, selection will favour the same phenotype for half of the generations, on average, and the other phenotype for the other half of the generations.