EFFECTS OF HABITAT DESTRUCTION IN A PREY-PREDATOR METAPOPULATION MODEL

A mean field, metapopulation model of a predator-prey interaction is d eveloped in order to understand the consequences of habitat destructio n at different trophic levels. Such a model allows us to explore diffe rent ecological scenarios (donor control vs. top-down control) by chan ging a single parameter. The response to habitat destruction is qualit atively the same for both predator and prey, although there are intere sting differences linked to the trophic position. A similar decrease i n the colonization rate affects the two species quite differently. Pre dators diminish faster than prey, and furthermore, the fraction of occ upied sites decreases more sharply as colonization rates are lowered, i.e. there is a nonlinear relationship between regional abundance and colonization rate. There is a well-defined threshold in the colonizati on rate below which the predator becomes extinct. Thus, dispersal rate is critical for predicting the consequences of habitat destruction. F inally, these results are compared with the behavior of a spatially ex plicit simulation. The only difference between the analytical model an d the simulation is that colonization is no longer a global phenomenon in the latter, but it is a local process, constrained to the nearest patches. The bulk of the results are similar to the mean field behavio r, and we comment on some differences related with non-homogeneity and real space. Some general implications for conservation biology and bi ological control are outlined. (C) 1998 Academic Press.