Great Basin Naturalist Memoirs


As is true of many assemblages of ecologically similar organisms, coexisting heteromyid rodent species differ conspicuously in morphology and in microhabitat affinity. These patterns are so common that their explanation represents a central problem of community ecology. In the case of desert rodents, two very different factors, predation and competition, have been advanced as the ultimate cause of the patterns. We outline the way in which each of these factors could produce observed community-level patterns and review the evidence for the action of each factor. We conclude that the "competition" hypothesis has more support at the moment, but that this is partly a result of the general lack of good experimental studies of predation in terrestrial vertebrate systems. We outline a general protocol for distinguishing the effects of predation and competition through careful examination of relationships between morphology, foraging and predator-avoidance abilities, and behavior. We think such "microecological" analysis of the consequences of morphology holds much promise for improving our understanding of community-level patterns of morphology and resource use.