Blas J, Bortolotti G R, Tella J L, Baos R, Marchant T A
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, Canada S7N 5E2.
Proc Natl Acad Sci U S A. 2007 May 22;104(21):8880-4. doi: 10.1073/pnas.0700232104. Epub 2007 May 15.
Short-term elevation of circulating glucocorticosteroids (GCs) in vertebrates facilitates the adoption of a distinct emergency life history state, which allows individuals to cope with perturbations and recover homeostasis at the expense of temporarily suppressing nonessential activities. Although GC responses are viewed as a major evolutionary mechanism to maximize fitness through stress management, phenotypic variability exists within animal populations, and it remains unclear whether interindividual differences in stress physiology can explain variance in unequivocal components of fitness. We show that the magnitude of the adrenocortical response to a standardized perturbation during development is negatively related to survival and recruitment in a wild population of long lived birds. Our results provide empirical evidence for a link between stress response, not exposure to stressors, and fitness in a vertebrate under natural conditions. Recent studies suggest that variability in the adrenocortical response to stress may be maintained if high and low GC responders represent alternative coping strategies, with differential adaptive value depending on environmental conditions. Increased fitness among low GC responders, having a proactive personality, is predicted under elevated population density and availability of food resources, conditions that characterize our study population.
脊椎动物体内循环糖皮质激素（GCs）的短期升高有助于进入一种独特的应急生命史状态，这使个体能够应对干扰并恢复体内平衡，但代价是暂时抑制非必要活动。尽管GC反应被视为通过应激管理使适应性最大化的一种主要进化机制，但动物种群中存在表型变异，应激生理学的个体差异是否能解释适应性明确组成部分的差异仍不清楚。我们发现，在长寿鸟类的野生种群中，发育过程中对标准化干扰的肾上腺皮质反应强度与生存和补充率呈负相关。我们的结果为自然条件下脊椎动物应激反应（而非暴露于应激源）与适应性之间的联系提供了实证证据。最近的研究表明，如果高GC反应者和低GC反应者代表不同的应对策略，且其适应性价值因环境条件而异，那么肾上腺皮质对应激反应的变异性可能会得以维持。在种群密度升高和食物资源充足的情况下（我们的研究种群具有这些特征），预计具有积极主动性格的低GC反应者的适应性会增强。
