Dataset to accompany manuscript: Seasonal variation of behavioural thermoregulation in a fossorial salamander (Ambystoma maculatum)

Temperature seasonality plays a pivotal role in shaping the thermal biology of ectotherms. However, we still have a limited understanding of how amphibians maintain thermal balance in the face of varying temperatures, especially in fossorial species. Due to thermal buffering underground, thermal ecology theory predicts relaxed selection pressure over thermoregulation in fossorial ectotherms. As a result, fossorial ectotherms typically show low thermoregulatory precision and low evidence of thermotactic behaviours in laboratory thermal gradients. Here, we evaluated how temperature selection (Tsel) and associated behaviours differed between seasons in a fossorial amphibian, the Spotted Salamander (Ambystoma maculatum). By comparing thermoregulatory parameters between the active and overwintering seasons, we show that A. maculatum engages in active behavioural thermoregulation despite being fossorial. In both seasons, Tsel was consistently offset higher than acclimatisation temperatures. Thermoregulation differed between seasons, with salamanders having higher Tsel and showing greater evidence of thermophilic behaviours in the active compared to the overwintering season. Additionally, our work lends support to experimental assumptions commonly made but seldom tested in thermal biology studies. Ultimately, our study demonstrates that the combination of careful behavioural and thermal biology measurements is a necessary step to better understand the mechanisms that underlie body temperature control in amphibians.

温度季节性在塑造变温动物（ectotherms）的热生物学特征方面发挥着关键作用。然而，我们对两栖动物如何在温度波动中维持体温平衡的认知仍较为有限，针对穴居物种的相关研究尤为匮乏。由于地下环境存在热缓冲效应，热生态学理论预测穴居变温动物的体温调节相关选择压力会有所松弛。因此，在实验室热梯度实验中，穴居变温动物通常表现出较低的体温调节精度，且趋热行为的相关证据也相对匮乏。本研究以穴居两栖动物斑点钝口螈（Ambystoma maculatum）为研究对象，探讨了不同季节下其体温选择温度（Temperature selection, Tsel）及相关行为的差异。通过比较活跃期与越冬期的体温调节参数，我们发现尽管斑点钝口螈为穴居物种，但其仍会开展主动的行为性体温调节。在两个季节中，其体温选择温度均持续高于适温驯化温度。不同季节下的体温调节模式存在显著差异：相较于越冬期，活跃期的斑点钝口螈体温选择温度更高，且表现出更显著的嗜热行为特征。此外，本研究为热生物学研究中常用却鲜有验证的实验假设提供了实证支持。综上，本研究表明，结合严谨的行为学与热生物学测量方法，是深入解析两栖动物体温调控机制的必要路径。