Costa-Pereira, RaulAraújo, Márcio SilvaOlivier, Renan da SilvaSouza, Franco L.Rudolf, Volker H.W.2018-11-012018-11-012018Costa-Pereira, Raul, Araújo, Márcio Silva, Olivier, Renan da Silva, et al.. "Prey Limitation Drives Variation in Allometric Scaling of Predator-Prey Interactions." <i>The American Naturalist,</i> 192, no. 4 (2018) The University of Chicago Press: E139-E149. https://doi.org/10.1086/698726.https://hdl.handle.net/1911/103277Ecologists have long searched for a universal size-scaling constant that governs trophic interactions. Although this is an appealing theoretical concept, predator-prey size ratios (PPSRs) vary strikingly across and within natural food webs, meaning that predators deviate from their optimal prey size by consuming relatively larger or smaller prey. Here we suggest that this unexpected variation in allometric scaling of trophic interactions can be predicted by gradients of prey limitation consistent with predictions from optimal foraging theory. We analyzed >6,000 trophic interactions of 52 populations from four tropical frog species along a gradient of prey limitation. The mean of PPSR and its variance differed up to two orders of magnitude across and within food webs. Importantly, as prey availability decreased across food webs, PPSR and its variance became more size dependent. Thus, trophic interactions did not follow a fixed allometric scaling but changed predictably with the strength of prey limitation. Our results emphasize the importance of ecological contexts in arranging food webs and the need to incorporate ecological drivers of PPSR and its variance in food web and community models.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlefood webpredator-prey mass ratiopredator-prey size ratioprey availabilitysize scalingtrophic interactionshttps://doi.org/10.1086/698726