Division of Ecology and Evolutionary Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G128QQ, United Kingdom.
Ecology. 2010 Sep;91(9):2756-68. doi: 10.1890/08-2269.1.
In many taxa the timing of metamorphosis is plastic in response to predation risk during the pre-metamorphic stage, and trends in both age and body size at metamorphosis have been the subject of much study. The responses to cues of predators are predominantly to be larger or equal-sized at the same age or older at metamorphosis. These observations are in direct contrast with existing theoretical treatments of this plasticity, which mostly predict earlier and smaller metamorphosis and never later and larger metamorphosis without invoking indirect effects on growth rate. Here we resolve the discrepancy between theory and observation using a dynamic state-dependent model that incorporates morphological and behavioral responses to predation risk. We allow prey to choose the optimal activity level and/or investment in defense over the growth period. We show that under certain conditions, metamorphosis at a larger size and later time is likely to be optimal. Our analysis allows us to make testable predictions about the changes in activity level of prey as they grow and how the effect of providing refuges will vary with predator type. Several of these predictions are supported by a meta-analysis of metamorphic responses to caged predators by larval amphibians and insects. Our predictions lead to insights about the feedback effects of antipredator responses on growth and subsequent implications for life history.
在许多分类群中，变态的时间是灵活的，可以根据变态前阶段的捕食风险做出反应，因此，变态的年龄和体型趋势一直是许多研究的主题。对捕食者线索的反应主要是在相同年龄或更老时体型更大或相等，而不是更早和更小的变态。这些观察结果与现有的关于这种可塑性的理论处理方法直接矛盾，这些理论大多预测更早和更小的变态，而从不预测没有间接影响生长速度的更晚和更大的变态。在这里，我们使用一个动态状态相关的模型来解决理论和观察之间的差异，该模型包含了对捕食风险的形态和行为反应。我们允许猎物在生长期间选择最佳的活动水平和/或防御投资。我们表明，在某些条件下，更大体型和更晚时间的变态更有可能是最优的。我们的分析使我们能够对猎物随着生长而改变活动水平的方式以及提供避难所的效果如何随捕食者类型而变化做出可测试的预测。这些预测中的几个得到了对幼虫两栖动物和昆虫的笼养捕食者的变态反应的荟萃分析的支持。我们的预测导致了关于抗捕食反应对生长的反馈效应以及对生活史的后续影响的深入了解。
