Krenek Lauren, Rudolf Volker H W
Department of Ecology and Evolutionary Biology, Rice University, Houston, TX, 77005, USA.
J Anim Ecol. 2014 Nov;83(6):1461-8. doi: 10.1111/1365-2656.12254. Epub 2014 Jun 25.
Non-consumptive effects (NCES) frequently lead to non-independent effects of multiple predators. While such emergent predator effects are ubiquitous in natural communities, the strength of these effects varies among studies and systems, making it difficult to predict a priory how changes in predator diversity influence prey suppression. Thus, identifying general scaling rules which can explain this variation of non-independent effects is vital for modelling natural communities and how they respond to biodiversity loss. Body size is a key trait determining the nature and strength of ecological interactions. While great progress has been made using allometric relationships to predict the interaction strength of predator-prey pairs, it is unknown whether similar relationships explain variation in the strength of NCEs, and how they are related to consumptive effects. Here, we experimentally manipulate the relative size difference of multiple predators to determine whether NCEs follow general allometric scaling relationships in an aquatic multi-predator system. Results demonstrate that the presence and strength of NCEs can vary dramatically across predator combinations. However, this variation scaled predictably with the size ratio of predators, increasing the size difference among predators increased NCEs. This pattern was driven by a size-mediated shift in 'food web motif' from competition to intraguild predation and a positive correlation of NCEs and intraguild predation rate. Results indicate that models which assume that consumers have independent effects are particularly likely to make erroneous predictions when predators differ substantially in size, but simple allometric relationships of NCEs could be used to correct this bias.
非消费性影响（NCEs）常常导致多种捕食者产生非独立影响。虽然这种捕食者的涌现效应在自然群落中普遍存在，但这些效应的强度在不同研究和系统中有所不同，这使得很难事先预测捕食者多样性的变化如何影响猎物抑制。因此，确定能够解释这种非独立影响变化的一般尺度规则，对于模拟自然群落及其对生物多样性丧失的反应至关重要。体型是决定生态相互作用性质和强度的关键特征。虽然利用异速生长关系预测捕食者 - 猎物对的相互作用强度已取得很大进展，但尚不清楚类似关系是否能解释非消费性影响强度的变化，以及它们与消费性影响如何相关。在此，我们通过实验操纵多种捕食者的相对大小差异，以确定在水生多捕食者系统中非消费性影响是否遵循一般的异速生长尺度关系。结果表明，非消费性影响的存在和强度在不同捕食者组合中可能有显著差异。然而，这种变化可根据捕食者的大小比进行可预测的缩放，捕食者之间大小差异的增加会增强非消费性影响。这种模式是由“食物网模式”从竞争到集团内捕食的大小介导转变以及非消费性影响与集团内捕食率的正相关驱动的。结果表明，当捕食者大小差异很大时，假设消费者具有独立影响的模型特别容易做出错误预测，但非消费性影响的简单异速生长关系可用于纠正这种偏差。
