Persistence of multispecies host-parasitoid interactions in spatially distributed models with local dispersal

Recent theoretical studies have shown that dispersal between neighbouring local populations can promote the persistence of interacting metapopulations, even when the local dynamics are unstable and the environment is uniform. This persistence is associated with striking and self-organized spatial patterns in the densities of the local populations. Here we extend previous work on spatially distributed host-parasitoid interactions to wider questions of community structure, by considering various three-species systems: two parasitoid species attacking a common host species; two host species attacked by a single parasitoid species; or a host-parasitoid-hyperparasitoid interaction. In each of these cases, multispecies coexistence of the total populations can occur, even though the local population dynamics are unstable. Furthermore, co-existence tends to be accompanied by some degree of persistent spatial segregation of the competing species, despite the completely uniform environment. At its most extreme, this results in one species being confined to small, relatively static, "islands" within the habitat, giving the appearance of isolated pockets of favourable habitat. That dynamics can impose and maintain such "self-organizing" spatial segregation of competing species, has interesting implications for understanding the local abundance of natural populations.