Data from: Stress hormone receptors change as range expansion progresses in house sparrows

As ranges expand, individuals encounter different environments at the periphery than at the centre of the range. Previously, we have shown that glucocorticoids (GCs) vary with range expansion: individuals at the range edge release more GCs in response to restraint. Here, we measured hippocampal mRNA expression of GC receptors (mineralocorticoid, MR and glucocorticoid, GR) in eight house sparrow (Passer domesticus) populations varying in age. We found that individuals closest to the range edge had the lowest expression of MR relative to GR; in all likelihood, this relationship was driven by a marginal reduction of MR mRNA at the range edge. Reduced MR (relative to GR) might allow enhanced GC binding to GR, the lower affinity receptor that would enhance a rapid physiological and behavioural response to stressors. The insights gained from this study are not only enlightening to introduced species, but may also predict how certain species will react as their ranges shift owing to anthropogenic changes.

随着物种分布范围扩张，个体在分布范围边缘与中心会遭遇截然不同的环境。此前我们的研究已证实糖皮质激素（glucocorticoids, GCs）的水平会随分布范围扩张发生改变：分布范围边缘的个体在受到束缚应激时，会释放更多的糖皮质激素。本研究针对8个不同形成时长的家雀（Passer domesticus）种群，检测了其海马体中两类糖皮质激素受体——盐皮质激素受体（mineralocorticoid, MR）与糖皮质激素受体（glucocorticoid, GR）——的mRNA表达水平。研究发现，距离分布范围边缘越近的个体，其盐皮质激素受体相对于糖皮质激素受体的mRNA表达水平越低；该关系大概率由分布范围边缘处MR mRNA的小幅下调所驱动。相较于糖皮质激素受体（GR，亲和力更低的受体），盐皮质激素受体（MR）表达水平的降低可能会增强GC与GR的结合能力，进而提升生物体对应激源的快速生理与行为响应。本研究所得的见解不仅对入侵物种研究具有启发价值，也可用于预测部分物种在人为活动导致分布范围变迁时的响应模式。