Despite being a major selective force, predation can induce puzzling variability in anti-predator responses-from lack of predator aversion to lifelong predator-induced fear. This variability is hypothesised to result from variation in the trade-offs associated with avoiding predators. But critical information on fitness outcomes of these trade-offs associated with anti-predator behaviours is lacking. We tested this trade-off hypothesis in Aedes aegypti, by examining oviposition site selection decisions in response towards larval predation risk and comprehensively measuring the fitness implications of trade-offs of avoiding larval predators, using three fitness measures: larval survival, development time and size. In a field study, we find that adult females show a surprisingly variable response to predators, ranging from attraction to avoidance. This variation is explained by fitness outcomes of oviposition along a predation-risk gradient that we measured in the laboratory. We show that ovipositing females could gain fitness benefits from ovipositing in pools with a low density of predators, rather than in predator-free pools, as predators provide a release from negative density effects of conspecific larvae that might co-occur in a pool. Interacting selection pressures may thus explain diverse prey responses. We suggest other systems in which similarly unexpected prey behaviour is likely to occur.

中文翻译：

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我敌人的敌人：多种相互作用的选择压力导致意外的反捕食者反应。

尽管掠夺是主要的选择性力量，但掠食仍会在反掠食者的反应中引起令人困惑的变化-从缺乏掠食者厌恶到终生掠食者诱发的恐惧。假设这种可变性是由于与避免掠夺者相关的权衡取舍而引起的。但是，缺乏与反捕食者行为相关的这些权衡取舍的适用性结果的关键信息。我们通过检查产卵位选择决策以应对幼虫捕食风险并使用三种适合度指标综合衡量避免幼虫捕食者的权衡适应性含义，从而在埃及伊蚊中测试了这种取舍假说，该方法采用三种适合度指标：幼虫存活，发育时间和大小。在野外研究中，我们发现成年雌性对捕食者的反应令人惊讶，范围从吸引到逃避不等。这种变化可以通过我们在实验室中测得的沿捕食-风险梯度的产卵适应性结果来解释。我们显示，在低密度捕食者的池中进行产卵，而不是在没有捕食者的池中进行产卵，雌性可能获得健身益处，因为捕食者提供了可能在池中共存的同种幼虫的负密度效应的释放。相互作用的选择压力因此可以解释多样化的猎物反应。我们建议在其他系统中也可能发生类似的意外捕食行为。因为捕食者会释放可能在池中同时出现的同种幼虫的负密度效应。相互作用的选择压力因此可以解释多样化的猎物反应。我们建议在其他系统中也可能发生类似的意外捕食行为。因为捕食者会释放可能在池中同时出现的同种幼虫的负密度效应。相互作用的选择压力因此可以解释多样化的猎物反应。我们建议在其他系统中也可能发生类似的意外捕食行为。