REGIONAL SPECIES POOLS AND THE ASSEMBLY OF LOCAL ECOLOGICAL COMMUNITIES

We model the sequential assembly of species into communities, using a notion of permanence from dynamical-systems theory, to investigate eff ects of species pools on the development of local communities. The res ults show that communities built from species-rich pools develop more slowly to invasion-resistant states. Fewer basal species are found loc ally where species pools are rich in consumers, although specializatio n by the consumers for different kinds of prey enables more basal spec ies to exist locally. The invasion-resistant states eventually achieve d by such an assembly process may be single communities or cyclic sequ ences of communities uninvadable by species not in the cycle. These en dstates of assembly are properties of the species pool, and the form t hey take depends on the nature of the pool. If made rich enough, speci es pools cause saturation of local communities such that the number of species present locally becomes uncoupled from the richness of the po ol. (C) 1997 Academic Press Limited.