Synthesizing intraguild predation theory and data

• Elizabeth T. Borer

Abstract
Although intraguild predation (IGP), a form of omnivory, is widespread in natural communities and has received significant attention in the recent theoretical and empirical literature, a gulf exists between theoretical predictions about the role of IGP in food webs and our understanding of its role in real communities. With few exceptions, the IGP literature falls into two categories operating at different time-scales: (1) theory presenting long-term effects of IGP on species persistence and population densities, and (2) short-term studies demonstrating IGP and, from theory, extrapolating the outcome for populations and communities. In addition, IGP models have been formulated for predator-prey (e.g. Holt and Polis 1997), host-parasitoid (Briggs 1993), and host-parasite (or pathogen) (e.g. Hochberg and Holt 1990) systems. Although the broad predictions of all of these model formulations are the same, this commonality is not generally recognized. I propose to synthesize this diffuse body of theory, assess the information available from short-term empirical studies, and test theoretical IGP predictions with empirical data.