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.

为维系生存，动物需对压力作出恰当应答。压力应答需付出高昂代价，因此个体在早期生命阶段接触潜在压力源的经历，可适应性地调整其成年后的压力应答模式，以适配所处的局部环境。然而，多重压力源如何影响压力应答的发育过程，以及性别在此过程中所扮演的角色，目前仍未明晰。特立尼达孔雀鱼（Poecilia reticulata）是一类小型鱼类，其两性间存在显著的生活史差异，且不同种群在捕食压力与社会密度方面存在变异。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命经历如何影响动物的激素型压力应答。针对成年个体，我们两次采集其皮质醇（cortisol）样本，以测量初始皮质醇释放量，以及其对重复出现的压力源的应答随时间的变化情况。两性在生理压力应答方面存在显著差异：雄性个体相对于其体重的皮质醇释放量高于雌性，且其皮质醇释放量并未随时间推移而降低。与之形成对比的是，除了在高种群密度且伴随捕食线索环境中饲养的雌性个体外，其余所有雌性个体的皮质醇释放量均随时间推移而降低。相较于雌性，雄性的皮质醇应答对当前环境与早期生命经历的响应更为迟钝，这与两性间的生活史差异相符。本研究强调了早期生命经历、相互作用的生态因子，以及压力应答调控中的性别差异的重要性。