Trade-offs, temporal variation, and species coexistence in communities with intraguild predation.
Intraguild predation/parasitism (IGP: competing species preying on or parasitizing each other) is widespread in nature, but the mechanisms by which intraguild prey and predators coexist remain elusive. Theory predicts that a trade-off between resource competition and IGP should allow local niche partitioning, but such trade-offs are expressed only at intermediate resource productivity and cannot explain observations of stable coexistence at high productivity. Coexistence must therefore involve additional mechanisms beside the trade-off, but very little is known about the operation of such mechanisms in nature. Here I present the first experimental test of multiple coexistence mechanisms in a natural community exhibiting IGP. The results suggest that, when resource productivity constrains the competition-IGP trade-off, a temporal refuge for the intraguild prey can not only promote coexistence, but also change species abundances to a pattern qualitatively different from that expected based on the trade-off or a refuge alone. This is the first empirical study to demonstrate a mechanism for why communities with IGP do not lose species diversity in highly productive environments. These results have implications for diversity maintenance in multi-trophic communities, and the use of multiple natural enemies in biological control.
Department of Ecology and Evolutionary Biology, University of California-Los Angeles, 621 Charles E. Young Drive South, Los Angeles, California 90095-1606, USA. amarasek@ucla.edu
Priyanga
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Amarasekare
D000818:Animals; D003163:Competitive Behavior / Q000502:physiology*; D017753:Ecosystem; D020387:Food Chain; D006790:Host-Parasite Interactions / Q000502:physiology*; D008954:Models, Biological; D011156:Population Density; D011157:Population Dynamics; D011158:Population Growth; D011235:Predatory Behavior / Q000502:physiology*; D013045:Species Specificity