Department of Biology, East Carolina University Greenville, NC 27858, USA.
Ecol Lett. 2012 Dec;15(12):1449-56. doi: 10.1111/ele.12005. Epub 2012 Sep 23.
The combined effects of multiple predators often cannot be predicted from their independent effects. Emergent multiple predator effects (MPEs) include risk enhancement, where combined predators kill more prey than predicted by their individual effects, and risk reduction, where fewer prey are killed than predicted. Current methods for detecting MPEs are biased because they assume linear functional responses and/or no prey depletion. As a result, past studies overestimated the occurrence of risk enhancement for additive designs, and tended to overestimate the occurrence of risk reduction for substitutive designs. Characterising the predators' functional responses and accounting for prey depletion reduces biases in detection, estimation, interpretation and generalisation of the emergent effects of predator diversity on prey survival. These findings have implications beyond MPE's and should be considered in all studies aimed at understanding how multiple factors combine when demographic rates are density dependent.
多种捕食者的综合效应通常不能从它们的独立效应中预测。突发的多重捕食者效应（MPE）包括风险增强，即联合捕食者杀死的猎物比它们各自的效应预测的要多，以及风险降低，即被杀死的猎物比预测的要少。目前用于检测 MPE 的方法存在偏差，因为它们假设线性功能反应和/或没有猎物枯竭。因此，过去的研究高估了加性设计中风险增强的发生，并且往往高估了替代设计中风险降低的发生。描述捕食者的功能反应并考虑猎物枯竭，可以减少检测、估计、解释和概括捕食者多样性对猎物生存的突发效应时的偏差。这些发现的意义超出了 MPE，并且应该在所有旨在理解当人口率依赖于密度时，多个因素如何结合的研究中考虑。
