Effects of habitat destruction and resource supplementation in a predator-prey metapopulation model

We developed a mean field, metapopulation model to study the consequences o f habitat destruction on a predator-prey interaction. The model complements and extends earlier work published by Bascompte and Sole (1998, J. theor. Biol. 195, 383-393) in that it also permits use of alternative prey (i.e., resource supplementation) by predators. The current model is stable wheneve r coexistence occurs, whereas the earlier model is not stable over the enti re domain of coexistence. More importantly, the current model permits an as sessment of the effect of a generalist predator on the trophic interaction. Habitat destruction negatively affects the equilibrium fraction of patches occupied by predators, but the effect is most pronounced for specialists. The effect of habitat destruction on prey coexisting with predators is depe ndent on the ratio of extinction risk due to predation and prey colonizatio n rate. When this ratio is less than unity, equilibrial prey occupancy of p atches declines as habitat destruction increases. When the ratio exceeds on e, equilibrial prey occupancy increases even as habitat destruction increas es; i.e., prey "escape" from predation is facilitated by habitat loss. Reso urce supplementation reduces the threshold colonization rate of predators n ecessary for their regional persistence, and the benefit derived from resou rce supplementation increases in a nonlinear fashion as habitat destruction increases. We also compared the analytical results to those from a stochas tic, spatially explicit simulation model. The simulation model was a discre te time analog of our analytical model, with one exception. Colonization wa s restricted locally in the simulation, whereas colonization was a global p rocess in the analytical model. After correcting for differences between no minal and effective colonization rates, most of the main conclusions of the two types of models were similar. Some important differences did emerge, h owever, and we discuss these in relation to the need to develop fully spati ally explicit analytical models. Finally, we comment on the implications of our results for community structure and for the conservation of prey speci es interacting with generalist predators. (C) 2001 Academic Press.