Increases in phenotypic variation under extreme (e.g. novel or stressful) environmental conditions are emerging as a crucial process through which evolutionary adaptation can occur. Lack of prior stabilizing selection, as well as potential instability of developmental processes in these environments, may lead to a release of phenotypic variation that can have important evolutionary consequences. Although such patterns have been shown in model study organisms, we know little about the generality of trait variance across environments for non-model organisms. Here, we test whether extreme developmental temperatures increase the phenotypic variation across diverse reptile taxa. We find that the among-individual variation in a key life-history trait (post-hatching growth) increases at extreme cold and hot temperatures. However, variations in two measures of hatchling morphology and in hatchling performance were not related to developmental temperature. Although extreme developmental temperatures may increase the variation in growth, our results suggest that plastic responses to stressful incubation conditions do not generally make more extreme phenotypes available to selection. We discuss the reasons for the general lack of increased variability at extreme incubation temperatures and the implications this has for local adaptation in hatchling morphology and physiology.

中文翻译：

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生活史中个体间差异的加剧而非形态与爬行动物的发育温度有关。

在极端（例如新的或有压力的）环境条件下表型变异的增加正在成为进化适应发生的关键过程。缺乏先前的稳定选择，以及在这些环境中发育过程的潜在不稳定性，可能导致表型变异的释放，这可能会产生重要的进化后果。尽管这种模式已在模型研究生物中显示出来，但我们对非模型生物跨环境的性状变异的普遍性知之甚少。在这里，我们测试极端发育温度是否会增加不同爬行动物类群的表型变异。我们发现，在极端寒冷和炎热的温度下，关键生活史特征（孵化后生长）的个体间差异会增加。然而，孵化形态和孵化性能的两种测量的变化与发育温度无关。尽管极端的发育温度可能会增加生长的变化，但我们的结果表明，对压力孵化条件的塑料反应通常不会使更极端的表型可供选择。我们讨论了在极端孵化温度下普遍缺乏变异性的原因以及这对孵化形态和生理学的局部适应的影响。我们的结果表明，对压力孵化条件的塑料反应通常不会使更极端的表型可供选择。我们讨论了在极端孵化温度下普遍缺乏变异性的原因以及这对孵化形态和生理学的局部适应的影响。我们的结果表明，对压力孵化条件的塑料反应通常不会使更极端的表型可供选择。我们讨论了在极端孵化温度下普遍缺乏变异性的原因以及这对孵化形态和生理学的局部适应的影响。