Nagel Rebecca, Kaiser Sylvia, Stainfield Claire, Toscani Camille, Fox-Clarke Cameron, Paijmans Anneke J, Costa Castro Camila, Vendrami David L J, Forcada Jaume, Hoffman Joseph I
Department of Animal Behaviour Bielefeld University Bielefeld Germany.
Department of Behavioural Biology University of Münster Münster Germany.
Ecol Evol. 2022 Mar 26;12(3):e8757. doi: 10.1002/ece3.8757. eCollection 2022 Mar.
Individuals are unique in how they interact with and respond to their environment. Correspondingly, unpredictable challenges or environmental stressors often produce an individualized response of the hypothalamic-pituitary-adrenal (HPA) axis and its downstream effector cortisol. We used a fully crossed, repeated measures design to investigate the factors shaping individual variation in baseline cortisol in Antarctic fur seal pups and their mothers. Saliva samples were collected from focal individuals at two breeding colonies, one with low and the other with high density, during two consecutive years of contrasting food availability. Mothers and pups were sampled concurrently at birth and shortly before weaning, while pups were additionally sampled every 20 days. We found that heritability was low for baseline cortisol, while within-individual repeatability and among-individual variability were high. A substantial proportion of the variation in baseline cortisol could be explained in pups and mothers by a combination of intrinsic and extrinsic factors including sex, weight, day, season, and colony of birth. Our findings provide detailed insights into the individualization of endocrine phenotypes and their genetic and environmental drivers in a wild pinniped. Furthermore, the strong associations between cortisol and life history traits that we report in fur seals could have important implications for understanding the population dynamics of species impacted by environmental change.
个体在与环境相互作用及对环境作出反应的方式上是独特的。相应地，不可预测的挑战或环境应激源通常会引发下丘脑 - 垂体 - 肾上腺（HPA）轴及其下游效应物皮质醇的个体化反应。我们采用完全交叉的重复测量设计，来研究塑造南极毛皮海狮幼崽及其母亲基线皮质醇个体差异的因素。在连续两年食物可获得性不同的情况下，从两个繁殖群体中的目标个体采集唾液样本，一个群体密度低，另一个群体密度高。母亲和幼崽在出生时和断奶前不久同时进行采样，幼崽还每隔20天额外采样一次。我们发现基线皮质醇的遗传力较低，而个体内重复性和个体间变异性较高。基线皮质醇变异的很大一部分可以通过内在和外在因素的组合来解释，这些因素包括性别、体重、日期、季节和出生群体。我们的研究结果为野生鳍足类动物内分泌表型的个体化及其遗传和环境驱动因素提供了详细的见解。此外，我们在毛皮海狮中报告的皮质醇与生活史特征之间的强关联，可能对理解受环境变化影响的物种的种群动态具有重要意义。
