Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada.
Ecology. 2011 Nov;92(11):2043-8. doi: 10.1890/11-0455.1.
Nonconsumptive predator effects are widespread and include plasticity as well as general stress responses. Caged predators are often used to estimate nonconsumptive effects, and numerous studies have focused on the larval stages of animals with complex life cycles. However, few of these studies test whether nonconsumptive predator effects, including stress responses, are exclusively sublethal. Nor have they assessed whether these effects extend beyond the larval stage, affecting success during stressful life-history transitions such as metamorphosis. We conducted experiments with larvae of a dragonfly (Leucorrhinia intacta) that exhibits predator-induced plasticity to assess whether the mere presence of predators affects larval survivorship, metamorphosis, and adult body size. Larvae exposed to caged predators with no ability to attack them had higher levels of mortality. In the second experiment, larvae reared with caged predators had higher rates of metamorphic failure, but there was no effect on adult body size. Our results suggest that stress responses induced by exposure to predator cues increase the vulnerability of prey to other mortality factors, and that mere exposure to predators can result in significant increases in mortality.
非消耗性捕食者效应广泛存在，包括可塑性和一般应激反应。笼养捕食者常用于估计非消耗性效应，许多研究都集中在生命周期复杂的动物的幼虫阶段。然而，这些研究中很少有测试非消耗性捕食者效应（包括应激反应）是否完全是亚致死性的。也没有评估这些效应是否会超出幼虫阶段，影响到诸如变态等压力大的生命史转折期间的成功。我们用一种蜻蜓（Leucorrhinia intacta）的幼虫进行了实验，该幼虫表现出了捕食者诱导的可塑性，以评估仅仅存在捕食者是否会影响幼虫的存活率、变态和成虫体型。暴露于无法攻击它们的笼养捕食者中的幼虫死亡率更高。在第二个实验中，饲养在笼养捕食者中的幼虫有更高的变态失败率，但对成虫体型没有影响。我们的结果表明，暴露于捕食者线索引起的应激反应会增加猎物对其他致死因素的脆弱性，仅仅暴露于捕食者就会导致死亡率显著增加。
