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

The mechanisms which in uence coexistence of specialist and gen-eralist species in the same environment are a key focus of ecological theory.
We use an agent-based model of commmunity assembly to show that the avail-
able 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 spec-
trum that is experienced by other species, in a way that disfavours generalists
and causes a community-wide shift towards specialist strategies. More gen-
erally, this suggests a mechanism by which apparently minor changes in the
specialist composition of an ecological community could have knock-on eects
across the entire community.