Mileva Viktoria R, Fitzpatrick John L, Marsh-Rollo Susan, Gilmour Kathleen M, Wood Chris M, Balshine Sigal
Animal Behaviour Group, Department of Psychology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
Physiol Biochem Zool. 2009 Nov-Dec;82(6):720-9. doi: 10.1086/605937.
In group-living species, dominant individuals are frequently aggressive toward subordinates, and such dominant aggression can lead to chronic stress, higher glucocorticoid levels, and decreased fitness for subordinates. However, in many cooperatively breeding species, it is surprisingly the dominants rather than the subordinates that exhibit higher levels of glucocorticoids, a possible consequence of the demands of maintaining high social rank and socially suppressing the reproduction of other group members. This study investigates the relationship between social status and circulating plasma cortisol in groups of the cooperatively breeding African cichlid Neolamprologus pulcher. Baseline (resting) levels of cortisol were quantified, as was the cortisol response following an acute stressor. Dominants had the higher cortisol concentrations, and these were not related to their social behavior. Cortisol concentrations correlated (positively) with social behaviors and general activity levels only in subordinate males, arguably the individuals with the least stability in the social group. No status-dependent differential responses to acute stress were detected, suggesting that the status-induced chronic stress has little effect on the capacity to mount a full stress response to large-scale, life-threatening risk.
在群居物种中，优势个体常常对从属个体具有攻击性，而这种优势攻击行为会导致从属个体产生慢性应激、糖皮质激素水平升高以及适应性下降。然而，在许多合作繁殖的物种中，令人惊讶的是，表现出较高糖皮质激素水平的是优势个体而非从属个体，这可能是维持高社会地位以及在社会层面抑制其他群体成员繁殖的需求所导致的结果。本研究调查了合作繁殖的非洲丽鱼科新亮丽鲷群体中社会地位与循环血浆皮质醇之间的关系。对皮质醇的基线（静息）水平进行了量化，同时也对急性应激源后的皮质醇反应进行了量化。优势个体的皮质醇浓度更高，且这些浓度与它们的社会行为无关。皮质醇浓度仅在从属雄性个体中（呈正相关）与社会行为和一般活动水平相关，从属雄性个体可以说是社会群体中稳定性最低的个体。未检测到对急性应激的状态依赖性差异反应，这表明状态诱导的慢性应激对针对大规模、危及生命的风险产生全面应激反应的能力影响很小。
