Crag lizards are restricted to montane areas where biota are strongly exposed to the effects of climate change. We investigated the factors shaping the distribution of Drakensberg crag lizards (Pseudocordylus melanotus melanotus; Cordylidae) by quantifying their elevational ranges, availability of shelter and prey as well as the thermal environment at three elevations. We recorded expected body temperatures using copper models of the lizards at each elevation in the field and in the laboratory, estimating the duration for which lizards must shelter from high temperatures. This correlated strongly with field observations of lizard activity during winter, spring and summer. Our models predicted that at lower elevations, lizards would shelter for longer periods each day, resulting in a marked reduction in time available for essential activities such as feeding and breeding, possibly explaining why these animals do not occur at lower elevations. The distribution and survival of these animals therefore appear to be impacted by the degree to which daytime temperatures limit their activity. Modelling future climate change scenarios at the high elevation site indicates that crag lizards would be resilient against small to moderate warming reflected by RCP4.5 climate change predictions, but populations are unlikely to persist under conditions predicted in the RCP8.5 scenario. This study is important as, unlike broader‐scope studies that cannot quantify climate change impacts on individual species, we combine detailed field data with laboratory measurements and modelling of a single species to assess the ecological constraints to which crag lizards are exposed.

中文翻译：

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高海拔岩蜥蜴对气候变化敏感吗？

蜥蜴只限于山地地区，那里的生物区系很容易受到气候变化的影响。我们调查了影响德拉肯斯堡蜥蜴（Pseudocordylus melanotus melanotus）分布的因素; 通过量化它们的海拔范围，庇护所和猎物的可用性以及在三个海拔高度的热环境，来确定它们的身分。我们在野外和实验室中的每个海拔高度使用蜥蜴的铜模型记录了预期的体温，从而估计了蜥蜴必须避开高温的持续时间。这与冬季，春季和夏季的蜥蜴活动现场观察密切相关。我们的模型预测，在海拔较低的地方，蜥蜴每天会躲藏较长时间，从而显着减少了用于诸如饲养和繁殖等基本活动的时间，这可能解释了为什么这些动物不在海拔较低的地方发生。因此，这些动物的分布和生存似乎受到白天温度限制其活动的程度的影响。对高海拔地区未来的气候变化情景进行建模表明，蜥蜴可以抵抗RCP4.5气候变化预测所反映的中小变暖，但是在RCP8.5情景中预测的条件下种群不可能持续存在。这项研究之所以重要，是因为与无法量化气候变化对单个物种的影响的广泛研究不同，我们将详细的现场数据与实验室测量结果和单个物种的建模相结合，以评估蜥蜴面临的生态约束。对高海拔地区未来的气候变化情景进行建模表明，蜥蜴可以抵抗RCP4.5气候变化预测所反映的中小变暖，但是在RCP8.5情景中预测的条件下种群不可能持续存在。这项研究之所以重要，是因为与无法量化气候变化对单个物种的影响的广泛研究不同，我们将详细的现场数据与实验室测量结果和单个物种的建模相结合，以评估蜥蜴面临的生态约束。对高海拔地区未来的气候变化情景进行建模表明，蜥蜴可以抵抗RCP4.5气候变化预测所反映的中小变暖，但是在RCP8.5情景中预测的条件下种群不可能持续存在。这项研究之所以重要，是因为与无法量化气候变化对单个物种的影响的广泛研究不同，我们将详细的现场数据与实验室测量结果和单个物种的建模相结合，以评估蜥蜴面临的生态约束。