Data from: Time-lagged effect of predators on tadpole behaviour and parasite infection

Prey should adjust their defences against natural enemies to match their current level of risk and balance other needs. This is particularly important when optimal defences represent trade-offs, as is the case with many predator-induced trait-mediated indirect effects (TMIEs) that are antagonistic to those promoting host resistance to parasites and pathogens. However, trade-offs may depend on whether different natural enemies are present simultaneously or represent temporally discrete threats. We found that larval amphibians (Anaxyrus americanus) previously exposed to predator cues did not engage in anti-parasite behaviours (activity increases) in response to a current risk of infection by a pathogenic trematode parasite compared to controls, resulting in higher infection intensities. This suggests that the memory of the likely more lethal threat (predation) had greater influence, maladaptively dampening tadpole activity. Incorporating complexity inherent in natural systems, including spatial and temporal overlap, is necessary to better understand natural enemy ecology and how TMIEs relate to infectious diseases.

猎物需针对天敌调整防御策略，以契合当前的风险等级，并平衡其他生存需求。当最优防御策略需进行多方权衡时，这一点尤为关键——诸多捕食者诱导的性状介导间接效应（TMIEs）便属此类，这类效应与提升宿主对寄生虫与病原体抗性的效应相互拮抗。不过，这类权衡效应是否出现，可能取决于不同天敌是同时存在，还是构成时序上离散的威胁。我们的研究发现，与对照组相比，此前暴露于捕食者信号的两栖类幼体（美洲蟾蜍，Anaxyrus americanus）并未在当前面临致病性吸虫感染风险时，展现出抗寄生虫行为（活动增强），最终导致更高的感染强度。这表明，对潜在致死性更强的捕食威胁的记忆发挥了更主导的影响，却适应不良地抑制了蝌蚪的活动。为更深入地解析天敌生态学，以及性状介导间接效应与传染病之间的关联，亟需纳入自然系统固有的复杂性，包括时空重叠效应在内。