Data from: Developmental plasticity of the stress response in female but not male guppies

To survive, animals must respond appropriately to stress. Stress responses are costly, so early-life experiences with potential stressors could adaptively tailor adult stress responses to local conditions. However, how multiple stressors influence the development of the stress response remains unclear, as is the role of sex. Trinidadian guppies (Poecilia reticulata) are small fish with extensive life history differences between the sexes and population variation in predation pressure and social density. We investigated how sex and early-life experience influence hormonal stress responses by manipulating conspecific density and perceived predation risk during development. In adults, we sampled cortisol twice to measure initial release and change over time in response to a recurring stressor. The sexes differed considerably in their physiological stress response. Males released more cortisol for their body mass than females and did not reduce cortisol release over time. By contrast, all females, except those reared at high density with predation cues, reduced cortisol release over time. Cortisol responses of males were less dynamic in response to current circumstances and early-life experiences than females, consistent with life history differences between the sexes. Our study underscores the importance of early-life experiences, interacting ecological factors, and sex differences in the organization of the stress response.

为维持生存，动物必须对压力刺激作出恰当应答。压力应答存在能量成本，因此早期暴露于潜在压力源的经历，可使成年个体的压力应答适应性地适配当地环境条件。然而，多重压力源如何影响压力应答的发育，以及性别的调控作用，目前仍未明确。
特立尼达孔雀花鳉（Poecilia reticulata）是一类小型淡水鱼类，其两性间存在显著的生活史差异，且不同种群的捕食压力与社会密度存在种群间变异。我们通过操控发育阶段的同种个体密度与感知到的捕食风险，探究了性别与早期生活经历对激素层面压力应答的影响。
在成年阶段，我们两次采集皮质醇（cortisol）样本，以量化初始皮质醇释放量，以及其对反复出现的压力源的随时间变化特征。研究结果显示，两性的生理压力应答存在显著差异：相较于同体重的雌性个体，雄性的皮质醇释放量更高，且不会随时间推移降低皮质醇释放水平。与之形成对照的是，除了在高密度且伴随捕食线索环境中发育的雌性个体外，其余雌性的皮质醇释放量均会随时间推移下降。
雄性的皮质醇应答相较于雌性，对当前环境条件与早期生活经历的动态响应性更弱，这与两性间的生活史差异相一致。本研究凸显了早期生活经历、交互作用的生态因子，以及压力应答调控通路中的性别差异的重要性。