Sa. Richards et al., Grazers and diggers: Exploitation competition and coexistence among foragers with different feeding strategies on a single resource, AM NATURAL, 155(2), 2000, pp. 266-279
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.