Most aspects of the lives of ectotherms are temperature dependent. Achieving the warmer body temperatures (T_bs) typically required for optimal performance can be particularly challenging for nocturnal ectotherms. Homonota darwinii—the world's southernmost gecko—is broadly distributed in southern Argentina (35–52 °S latitude) where cold climates over parts of its range likely pose an additional performance challenge for this nocturnal lizard. We hypothesized that the southernmost populations of this species would be the most thermally challenged, as evidenced by a decline in temperature‐dependent sprint performance with increasing latitude. A temperature‐dependent depression in locomotory performance may indicate suboptimal performance in other thermally dependent traits linked to fitness (e.g., foraging efficiency, metabolism). We measured sprint performance at five ecologically relevant T_bs for four populations spanning most of the latitudinal range of H. darwinii. We also recorded annual operative temperatures (T_es) at each site on the surface and in refuges used by the geckos. Sprint data indicated differences in maximum performance over the range of H. darwinii, but not the latitudinal decline predicted. Instead, sprint performance was likely influenced by climatic variability associated with each site's elevation. Geckos from most populations had a broad range of T_bs over which sprint performance was optimal, albeit twofold to threefold lower than other geckos. This is indicative of eurythermy, the ability to perform well over a wide range of temperatures. We discuss this finding in the context of alternative hypotheses concerning performance tradeoffs in nocturnal ectotherms.

中文翻译：

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保暖并不总是更好：在寒冷气候的壁虎中表现出温热。

等温线寿命的大多数方面都取决于温度。要获得最佳性能通常需要的较暖的体温（T _b s），对于夜间的外热疗法尤其具有挑战性。达尔文人壁虎是世界上最南端的壁虎，广泛分布于阿根廷南部（北纬35-52°S），在该地区的部分地区，寒冷的气候可能会对这种夜行性蜥蜴构成额外的性能挑战。我们假设该物种的最南端种群将受到最大的热挑战，这一点可以通过随纬度增加而随温度变化的冲刺性能下降来证明。运动性能的温度依赖性下降可能表明与适应性相关的其他热依赖性性状（例如，觅食效率，新陈代谢）表现不佳。我们测量性能冲刺五生态相关牛逼_b S代表四个群体跨越大多数的纬度范围的H.达尔文。我们还记录了地面上每个位置以及壁虎所使用的避难所中的年度手术温度（T _e s）。冲刺数据表明在达尔文氏梭菌范围内最大性能的差异，但未预测到纬度下降。相反，短跑性能很可能受到与每个地点的海拔高度相关的气候变化的影响。从大多数人群壁虎有广泛的Ť _b结束了其冲刺性能是最佳的，尽管双重到三倍比其他壁虎降低。这表明了热疗，在广泛的温度范围内表现良好的能力。我们在关于夜间等温线性能折衷的替代假设的背景下讨论了这一发现。