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，动物必须对压力作出恰当应答。压力应答存在高昂的代谢与生理代价，因此动物在早期生活中接触潜在压力源的经历，可适应性地将成体的压力应答调整至适配当地环境的状态。然而，多重压力源如何影响压力应答的发育过程，以及性别在其中所扮演的角色，目前仍不明晰。特立尼达孔雀鱼（Poecilia reticulata）是一种小型鱼类，其雌雄个体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。本研究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如何影响激素水平的压力应答。针对成体个体，我们两次采集样本以检测皮质醇的初始释放量，以及其在重复性压力源刺激下随时间的变化情况。研究发现，雌雄个体的生理压力应答存在显著差异：雄性个体按体重换算后释放的皮质醇量高于雌性，且其皮质醇释放量未随时间出现下降；与之相反，除了在高密环境且伴随捕食信号条件下饲养的雌性个体外，其余所有雌性个体的皮质醇释放量均随时间出现下降。相较于雌性个体，雄性的皮质醇应答对当前环境与早期生活经历的响应动态性更低，这与雌雄间的生活史差异相一致。本研究强调了早期生活经历、相互作用的生态因子，以及性别差异在压力应答调控机制中的重要性。