Grazers and diggers: Exploitation competition and coexistence among foragers with different feeding strategies on a single resource

A mathematical model is presented that describes a system where two consume r species compete exploitatively for a single renewable resource. The resou rce is distributed in a patchy but homogeneous environment; that is, all pa tches are intrinsically identical. The two consumer species are referred to as diggers and grazers, where diggers deplete the resource within a patch to lower densities than grazers. We show that the two distinct feeding stra tegies can produce a heterogeneous resource distribution that enables their coexistence. Coexistence requires that grazers must either move faster tha n diggers between patches or convert the resources to population growth muc h more efficiently than diggers. The model shows that the functional form o f resource renewal within a patch is also important for coexistence. These results contrast with theory that considers exploitation competition for a single resource when the resource is assumed to be well mixed throughout th e system.