Resource spectrum engineering by specialist species can shift the specialist-generalist balance

The mechanisms which influence coexistence of specialist and generalist species in the same environment are a key focus of ecological theory. We use an agent-based model of community assembly to show that the available resource spectrum (distribution of resources along a niche axis) can play an important role in determining the specialist-generalist balance, even in the absence of spatial structure. Our results reveal a phenomenon that we term 'resource spectrum engineering', in which opportunistic specialists occupying small niches in a mostly generalist community can change the resource spectrum that is experienced by other species, in a way that disfavours generalists and causes a community-wide shift towards specialist strategies. More generally, this suggests a mechanism by which apparently minor changes in the specialist composition of an ecological community could have knock-on effects across the entire community.