Data set to accompany manuscript "Seasonal plasticity in the thermal sensitivity of metabolism but not water loss in a fossorial ectotherm"

Ectotherms from highly seasonal habitats should have enhanced potential for physiological plasticity to cope with climatic variability. However, whether this pattern is applicable to fossorial ectotherms, who are potentially buffered from thermal variability, is still unclear. Here, we evaluated how seasonal acclimatisation (spring vs. autumn) affected the thermal sensitivity of standard metabolic rates (SMR), rates of evaporative water loss (EWL), and skin resistance to water loss (Rs) in the Spotted Salamander (Ambystoma maculatum). We hypothesised that temperature would have both short- and long-term effects over traits (i.e., acute exposure to test temperatures and seasonal acclimatisation, respectively). After accounting for body mass and sex, we found that short-term changes in temperature led to an increase in SMR, EWL, and Rs. Additionally, SMR and Rs differed between seasons, but EWL did not. Sustaining low SMR and high Rs in the spring may allow salamanders to allocate energy toward overwintering emergence and breeding while simultaneously maximising water conservation. By contrast, maintaining high SMR and low Rs in the autumn may allow salamanders to forage aboveground on rainy nights to replenish energy reserves in preparation for the winter. Despite the common assumption that fossorial ectotherms are buffered from thermal effects, our study shows that functional differences between seasons (i.e., breeding in the spring and provisioning in the autumn) are accompanied by seasonal changes in energetic and hydroregulatory requirements.

栖息于高度季节性生境的变温动物（Ectotherms）理应具备更强的生理可塑性，以应对气候变异性。然而，这一规律是否适用于穴居变温动物（fossorial ectotherms）——这类类群或可通过穴居生境缓冲温度波动的影响——目前仍不明确。本研究以斑点钝口螈（Ambystoma maculatum）为实验对象，探究了季节驯化（春季与秋季）对其标准代谢率（SMR）、蒸发失水率（EWL）及皮肤失水阻力（Rs）的温度敏感性的影响。我们提出假说：温度对上述性状兼具短期与长期效应，分别对应测试温度的急性暴露过程与季节驯化过程。在控制体重与性别因素后，研究发现温度的短期变化会导致标准代谢率、蒸发失水率及皮肤失水阻力显著升高。此外，标准代谢率与皮肤失水阻力在季节间存在显著差异，但蒸发失水率并无此规律。春季维持较低的标准代谢率与较高的皮肤失水阻力，或可帮助斑点钝口螈将能量分配至越冬出蛰与繁殖活动，同时最大化水分保有能力。相较之下，秋季维持较高的标准代谢率与较低的皮肤失水阻力，或可帮助斑点钝口螈在雨夜外出地面觅食，以补充能量储备，为越冬做好准备。尽管学界普遍认为穴居变温动物可免受温度效应的直接影响，但本研究表明，季节间的功能差异（即春季繁殖与秋季能量储备）伴随有能量代谢与水分调节需求的季节性变化。