Data from: Age-dependent effects of predation risk on reproductive success in a freshwater snail

Reproductive performance is often age-dependent, showing patterns of improvement and/or senescence as well as trade-offs with other traits throughout the lifespan. High levels of extrinsic mortality (e.g., from predators) have been shown to sometimes, but not always, select for accelerated actuarial senescence in nature and in the lab. Here we explore the inductive (i.e., plastic) effects of predation risk (i.e., non-lethal exposure to chemical cues from predators) on the reproductive success of freshwater snails (Physa acuta). Snails were reared either in the presence or absence of chemical cues from predatory crayfish and mated early in life or late in life (a 2×2 factorial design); we measured egg hatching and early post-hatching survival of their offspring. Both age and predation risk reduced reproductive success, illustrating that predation risk can have a cross-generational effect on the early survival of juveniles. Further, the decline in reproductive success was over 3 times faster under predation risk compared to the no-predator treatment, an effect that stemmed from a disproportionate, negative effect of predation risk on the post-hatching survival instead of hatching rate. We discuss our results in terms of a hypothesized consequence of elevated stress hormone levels.繁殖性能通常呈年龄依赖性，在整个生命周期中会呈现出性能提升和/或衰老的模式，同时还会与其他性状存在进化权衡关系。高水平的外源性死亡率（extrinsic mortality，例如源自捕食者的威胁）已被证实，有时但并非总能在自然与实验室环境中，促使种群演化出加速的年龄相关衰老（actuarial senescence）。本研究探讨了捕食风险（predation risk，即非致死性暴露于捕食者释放的化学信号）对淡水螺（尖膀胱螺，Physa acuta）繁殖成功率的诱导性（即可塑性）效应。实验采用2×2析因设计：将淡水螺分别置于有捕食性螯虾化学信号与无该信号的环境中饲养，并设置早期交配与晚期交配两组处理；随后测定了其后代的卵孵化率与孵化早期存活率。结果显示，螺的繁殖年龄与捕食风险均会降低其繁殖成功率，表明捕食风险可对幼体的早期存活产生跨代效应。进一步分析表明，捕食风险组的繁殖成功率下降速度较无捕食者对照组快3倍以上，该效应源于捕食风险对孵化后存活率的不成比例负面影响，而非对卵孵化率的影响。最后，我们结合应激激素水平升高的相关假说对本研究结果展开了讨论。