Department of Biological Sciences, Brock University, St Catharines, ON, Canada, L2S 3A1.
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada, M5S 1A4.
J Exp Biol. 2024 Nov 1;227(21). doi: 10.1242/jeb.249319. Epub 2024 Oct 24.
To decide whether to remain underground or to emerge from overwintering, fossorial ectotherms simultaneously process environmental, gravitational and circannual migratory cues. Here, we provide an experimental framework to study the behaviour of fossorial ectotherms during soil temperature inversion - a phenomenon that marks the transition between winter and spring - based on three non-mutually exclusive hypotheses (thermoregulation, negative geotaxis and migration restlessness). Using a vertical thermal gradient, we evaluated how temperature selection (Tsel), activity and vertical position selection differed under simulated soil temperature inversion (contrasting the active versus overwintering thermal gradients) in the spotted salamander (Ambystoma maculatum). Salamanders had different Tsel and activity levels between gradients, but selected similar heights regardless of thermal gradient orientation. Negative geotaxis may explain responses to changes in vertical thermal gradient orientation, with migratory restlessness contributing to differences in activity levels. Ultimately, our work should benefit those who aim to better understand the biology of fossorial ectotherms.
为了决定是否留在地下或从冬眠中出现，穴居的变温动物同时处理环境、重力和年迁移线索。在这里，我们提供了一个实验框架来研究穴居变温动物在土壤温度反转期间的行为，土壤温度反转是冬季和春季之间过渡的标志，这是基于三个非互斥假设（体温调节、负趋地性和迁移不安）。我们使用垂直温度梯度，评估了斑点蝾螈（Ambystoma maculatum）在模拟土壤温度反转（对比主动和冬眠的热梯度）时，温度选择（Tsel）、活动和垂直位置选择如何在梯度之间有所不同。蝾螈在梯度之间有不同的 Tsel 和活动水平，但无论热梯度方向如何，选择的高度相似。负趋地性可能解释了对垂直热梯度方向变化的反应，而迁移不安则导致了活动水平的差异。最终，我们的工作应该使那些旨在更好地了解穴居变温动物生物学的人受益。
