Allopatric coevolution: Migratory predators may facilitate mimicry between geographically nonoverlapping species.

A natural assumption in evolutionary biology is that to coevolve, species must interact with each other and should therefore co-occur. However, many evolutionary dynamics may be mediated by migratory or vector-borne agents, raising the possibility of coevolutionary interactions between allopatric species. In mimicry theory, a recurring assumption is that all species participating in a mimicry system must be sympatric, because predators must encounter both model and mimic/co-mimic to confuse between them. While it has been suggested that mimicry may occur between allopatric species through the mediation of migratory predators, this possibility has remained largely unexplored, theoretically and empirically. To explore this question, we used computer simulations that model the population dynamics of two populations of unprofitable aposematic prey connected by migratory predators. Each population in the simulation is affected by both local predators, which do not migrate and are therefore not directly affected by the foreign signal, and by migratory predators, which are affected by the signals in both populations. Our results demonstrate that migratory predators may drive the evolution of mimicry between allopatric species in a wide range of ecological scenarios, and that this phenomenon may be constrained by selective pressure from local predators. Furthermore, we suggest that migratory agents may facilitate not only mimicry, but a wide range of hitherto unappreciated coevolutionary interactions between allopatric species. In light of this perspective, we identify and discuss potential case studies of mimicry and other forms of coevolution occurring between allopatric species, including host-pathogen and herbivore-plant arms races.