Data from: Glucocorticoid-environment relationships align with responses to environmental change in two co-occurring congeners

As more species undergo range shifts in response to climate change, it is increasingly important to understand the factors that determine an organism’s realized niche. Physiological limits imposed by abiotic factors constrain the distributions of many species. Because glucocorticoids are essential to the maintenance of physiological homeostasis, identifying glucocorticoid-environment relationships may generate critical insights into both limits on species distributions and potential responses to environmental change. We explored relationships between variability in baseline glucocorticoids and sensitivity to environmental conditions in two chipmunk species characterized by divergent patterns of spatial, genetic, and morphological change over the past century. Specifically, we investigated whether the alpine chipmunk (Tamias alpinus), which has undergone pronounced changes, displays greater glucocorticoid sensitivity to environmental parameters than the lodgepole chipmunk (T. speciosus), which has exhibited little change over the same interval. From 2013-2015, we collected environmental data and fecal glucocorticoid metabolite (FGM) samples from these species. Using generalized linear mixed models and a model averaging approach, we examined the impacts of environmental and individual phenotypic parameters on FGMs. We found pronounced interspecific differences, with environmental parameters being better predictors of FGMs in T. alpinus. FGMs in this species were particularly elevated in less climatically suitable habitats and in areas with higher maximum daily temperatures. Individual phenotypic traits were not predictive of FGMs in T. alpinus, although they were highly predictive for T. speciosus. Collectively, these findings support the hypothesis that T. alpinus is more sensitive to environmental change. More generally, our results suggest that both phenotypic attributes and environmental conditions contribute to FGM responses but that the relative contributions of these factors differ among taxa, including among closely related species. Finally, our analyses underscore the value of glucocorticoids as bioindicators of sensitivity to environmental change in species for which the factors affecting stress physiology have been assessed.

随着更多物种为应对气候变化而发生分布范围转移，解析决定生物体实际生态位（realized niche）的关键因素愈发重要。非生物因子施加的生理限制，制约了诸多物种的分布格局。由于糖皮质激素（glucocorticoids）对维持生理稳态至关重要，厘清糖皮质激素与环境之间的关联，或能为物种分布限制以及对环境变化的潜在响应机制提供关键洞见。本研究聚焦过去一个世纪以来在空间、遗传与形态特征上呈现出分化演化模式的两种花栗鼠物种，探讨了基础糖皮质激素水平变异与物种对环境条件敏感性之间的关联。具体而言，我们旨在验证：经历了显著分布变化的高山花栗鼠（Tamias alpinus），其对环境参数的糖皮质激素敏感性是否高于同期仅发生微小变化的黑松花栗鼠（T. speciosus）。2013至2015年间，我们针对这两个物种收集了环境数据与粪便糖皮质激素代谢物（fecal glucocorticoid metabolite，FGM）样本。借助广义线性混合模型（generalized linear mixed models）与模型平均法，我们分析了环境因子与个体表型参数对粪便糖皮质激素代谢物水平的影响。研究发现了显著的种间差异：环境参数对高山花栗鼠的粪便糖皮质激素代谢物水平具有更强的预测能力。该物种的粪便糖皮质激素代谢物水平在气候适宜度较低的生境，以及日最高温更高的区域显著升高。而个体表型性状对高山花栗鼠的粪便糖皮质激素代谢物水平并无预测效力，但却能高度预测黑松花栗鼠的相关指标。综合来看，这些结果支持了'高山花栗鼠对环境变化更为敏感'的假说。更宽泛而言，我们的研究结果表明，表型属性与环境条件均会对粪便糖皮质激素代谢物的响应产生影响，但二者的相对贡献在不同类群（包括近缘物种之间）存在差异。最后，本研究的分析凸显了糖皮质激素作为生物指示剂的价值：在已明确影响物种应激生理的因子的类群中，糖皮质激素可用于表征物种对环境变化的敏感性。