PERSISTENCE OF MULTISPECIES HOST-PARASITOID INTERACTIONS IN SPATIALLYDISTRIBUTED MODELS WITH LOCAL DISPERSAL

Recent theoretical studies have shown that dispersal between neighbour ing local populations can promote the persistence of interacting metap opulations, even when the local dynamics are unstable and the environm ent 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 com mon host species; two host species attacked by a single parasitoid spe cies; or a host-parasitoid-hyperparasitoid interaction. In each of the se 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 spat ial segregation of the competing species, despite the completely unifo rm 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 seg regation of competing species, has interesting implications for unders tanding the local abundance of natural populations. (C) 1996 Academic Press Limited.