Theory suggests that the response of communities to habitat subdivision dep
ends on both species' characteristics and the extent to which species inter
act. For species with dynamics that are independent of other species, subdi
vision is expected to promote regional extinction as populations become sma
ll and isolated. By contrast, intermediate levels of subdivision can facili
tate persistence of strongly interacting species. Consistent with this pred
iction, experimental subdivision lengthened persistence of some species, al
tering the extent of food web collapse through extinction. Extended persist
ence was associated with immigration rescuing a basal prey species from loc
al extinction. As predicted by food web theory, habitat subdivision reduced
population density of a top predator. Removal of this top predator from un
divided microcosms increased the abundance of two other predator species, a
nd these changes paralleled those produced by habitat subdivision. These re
sults show that species interactions structured this community, and illustr
ate the need for investigations of other communities.