title: Body mass constraints on feeding rates determine the consequences of predator loss.
abstract: Understanding effects of species loss in complex food webs with multiple trophic levels is complicated by the idiosyncrasy of the predator effects on lower trophic levels: direct and indirect effects intermingle and may increase, decrease or not affect ecosystem functioning. We introduce a reductionist approach explaining a predator's trophic effect only by empirically well-founded body-mass constraints on abundance, diet breadth and feeding strength. We demonstrate that this mechanistic concept successfully explains the positive, negative and neutral net effects of predators on decomposers in a litter microcosm experiment. This approach offers a new perspective on the interplay of complex interactions within food webs and is easily extendable to include phylogenetic and other body-mass independent traits. We anticipate that allometry will substantially improve our understanding of idiosyncratic predator effects in experiments and the consequences of predator loss in natural ecosystems.
authors.affiliation: Georg August University Göttingen, J.F. Blumenbach Institute of Zoology and Anthropology, Berliner Str. 28, 37073 Göttingen, Germany. f_schneider@bio.tu-darmstadt.de
authors.forename: Florian Dirk
authors.initials: FD
authors.lastname: Schneider
authors.forename: Stefan
authors.initials: S
authors.lastname: Scheu
authors.forename: Ulrich
authors.initials: U
authors.lastname: Brose
mesh_terms: D000818:Animals; D001181:Arthropods / Q000502:physiology*; D049628:Body Size; D005247:Feeding Behavior; D020387:Food Chain; D008925:Mites / Q000502:physiology; D011235:Predatory Behavior / Q000502:physiology; D013112:Spiders / Q000502:physiology