Coexistence of two stage-structured intraguild predators

An organism can be defined as omnivorous if it feeds on more than one trophic level. Omnivory is present in many ecosystems and multiple omnivorous species can coexist in the same ecosystem. How coexisting omnivores are able to avoid competitive exclusion is very much an open question. In this paper we analyze a model of a community consisting of two omnivorous predators and a basal resource. The population of both predators is explicitly structured into juveniles and adults, of which juveniles only feed on basal resource and adults feed on a varied proportion of basal resource and juveniles of the other population. We thereby separate the omnivorous roles (competitor for basal resource and predator of competitors) over life history. We show in this study that persistence of multiple omnivorous predators is possible when predators differ in adult diets. In this case, coexistence occurs because community dynamics force one of the model species to act as a predator and the other to act as a consumer. We conclude that separation of omnivorous roles over life history not only offers an explanation on why systems with omnivory can persist, but also how multiple omnivores can coexist at the same trophic levels of those systems. (C) 2012 Elsevier Ltd. All rights reserved.