Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany; Münster Graduate School of Evolution, University of Münster, Hüfferstr. 1a, 48149 Münster, Germany.
Population Ecology Group, Institute of Ecology, Friedrich Schiller University, Dornburgerstr. 159, 07743 Jena, Germany.
Horm Behav. 2021 May;131:104967. doi: 10.1016/j.yhbeh.2021.104967. Epub 2021 Apr 13.
The time of dominance rank acquisition is a crucial phase in male life history that often affects reproductive success and hence fitness. Hormones such as testosterone and glucocorticoids can influence as well as be affected by this process. At the same time, hormone concentrations can show large individual variation. The extent to which such variation is repeatable, particularly in dynamic social settings, is a question of current interest. The aim of the present study was therefore to investigate how dominance rank and individual differences contribute to variance in hormone concentrations during male rank acquisition in a complex social environment. For this purpose, dominance rank as well as baseline testosterone, baseline cortisol, and cortisol responsiveness after exposure to a novel environment were determined in colony-housed guinea pig males from late adolescence through adulthood. Hormone-dominance relationships and repeatability of hormone measures beyond their relation to rank were assessed. There was a significant positive relationship between baseline testosterone and rank, but this link became weaker with increasing age. Baseline cortisol or cortisol responsiveness, in contrast, were not significantly related to dominance. Notably, all three endocrine parameters were significantly repeatable independent of dominance rank from late adolescence through adulthood. Baseline testosterone and cortisol responsiveness showed a significantly higher repeatability than baseline cortisol. This suggests that testosterone titres and cortisol responsiveness represent stable individual attributes even under complex social conditions.
获得支配等级的时间是雄性生活史中的一个关键阶段，它经常影响生殖成功，从而影响适应度。睾酮和皮质醇等激素可以影响这个过程，也可以被这个过程影响。同时，激素浓度可能会表现出很大的个体差异。这种变异在多大程度上是可重复的，特别是在动态的社会环境中，这是当前关注的问题。本研究的目的是调查在复杂的社会环境中，支配等级和个体差异如何影响雄性在获得支配等级过程中激素浓度的变化。为此，在殖民地饲养的豚鼠雄性从青春期后期到成年期，确定了支配等级以及基础睾酮、基础皮质醇和暴露于新环境后的皮质醇反应性。评估了激素-支配关系以及激素测量值的可重复性，超出了它们与等级的关系。基础睾酮与等级呈显著正相关，但这种联系随着年龄的增长而减弱。相比之下，基础皮质醇或皮质醇反应性与支配地位没有显著关系。值得注意的是，从青春期后期到成年期，所有三个内分泌参数都与支配等级无关，具有显著的可重复性。基础睾酮和皮质醇反应性的可重复性明显高于基础皮质醇。这表明，即使在复杂的社会条件下，睾酮和皮质醇反应性也代表了稳定的个体特征。
