Predator diversity and trophic interactions

• Published in: Ecology (Durham) 2007-10, Vol.88 (10), p.2415-2426
• Main Author: Schmitz, O.J
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal ecology; Animal, plant and microbial ecology; Animals; Biodiversity; Biological and medical sciences; Concepts & Synthesis: Emphasizing New Ideas to Stimulate Research in Ecology; Ecology; Ecosystem; Ecosystem studies; Ecosystems; Experiments; field experimentation; Food Chain; Fundamental and applied biological sciences. Psychology; General aspects; habitat domain; Habitats; Hunting; hunting mode; intraguild predation; linear models; meta-analysis; microhabitats; multiple predators; nonlinear models; Population Dynamics; Predation; predator and prey traits; predator diversity; predator-prey relationships; Predators; Predatory Behavior - physiology; risk enhancement and reduction; spatial data; Species; Species diversity; Species Specificity; trophic interactions; Trophic relationships; Wildlife habitats
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/06-0937.1

The recognition that predators play important roles in ecosystems has prompted research to resolve how combinations of predator species influence ecosystem functions. Interactions among predator species and their prey can lead to a host of linear and nonlinear effects. Understanding the conditions causing these effects is critical for assigning predator species to functional groups in ways that lead to predictive theory of predator diversity effects on trophic interactions. To this end, I provide a synthesis of experiments examining multiple-predator-species effects on mortality of single shared prey. I show how experimental design and experimental venue can determine the conclusion about the importance of predator diversity on trophic interactions. In addition, I link natural history insights on predator species habitat and hunting behavior with linear and nonlinear multiple-predator effects to derive a new concept of predator diversity effects on trophic interactions. This concept holds that the nature of predator diversity effects is contingent upon predator species hunting mode plus predator and prey species habitat domain (defined as the spatial extent to which a microhabitat is used by a species). This concept allows the classification of multiple-predator effects into four broad functional categories: substitutable, nonlinear due to predator species interference, nonlinear due to intraguild predation, and nonlinear due to predator species synergism. Experimental evidence so far provides ample and comparatively equal support for substitutable, interference, and intraguild effects, and equivocal support for nonlinear synergisms. The paper closes by discussing ways to further a research program aimed at using the building blocks presented here to understand predator functional diversity and trophic interactions in complex ecological systems.