A LARGE-SCALE METAPOPULATION MODEL OF INTERSPECIFIC COMPETITION AND ENVIRONMENTAL-CHANGE

A spatially explicit model is developed for metapopulations occupying habitat patches whose quality varies over space and time and where dispersal is localized. Computer simulations of the model showed that broad-niched, good-dispersing ''generalist'' species were better able to track environmental change than ''specialist'' species. The outcome of interspecific competition also varied with landscape type (degree of fragmentation) and rate of environmental change. Under a constant environment or slow environmental change, interspecific competition involved local (within-cell) processes that favored the specialist species over the generalist. Under moderate to high rates of environmental change local population dynamics increasingly favored high immigration rates of the generalist over the local competitive ability of the specialist. With rapid environmental change and a highly fragmented patch landscape the generalist was able to limit the ability of the specialist to persist and/or track the shifting environment. Our results suggest that under environmental change communities will increasingly become dominated by generalist species. Our approach extends metapopulation models to treat patterns of continental species diversity, and other environmental change models to include a population inhabiting a landscape of interconnected patches rather than a single habitat patch.