Data from: Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

Global warming is increasing the overheating risk for many organisms, though the potential for plasticity in thermal tolerance to mitigate this risk is largely unknown. In part, this shortcoming stems from a lack of knowledge about global and taxonomic patterns of variation in tolerance plasticity. To address this critical issue, we test leading hypotheses for broad-scale variation in ectotherm tolerance plasticity using a dataset that includes vertebrate and invertebrate taxa from terrestrial, freshwater, and marine habitats. Contrary to expectation, plasticity in heat tolerance was unrelated to latitude or thermal seasonality. However, plasticity in cold tolerance is associated with thermal seasonality in some habitat types. In addition, aquatic taxa have approximately twice the plasticity of terrestrial taxa. Based on the observed patterns of variation in tolerance plasticity, we propose that limited potential for behavioral plasticity (i.e., behavioral thermoregulation) favors the evolution of greater plasticity in physiological traits, consistent with the “Bogert Effect”. Finally, we find that all ectotherms have relatively low acclimation in thermal tolerance, and demonstrate that overheating risk will be minimally reduced by acclimation in even the most plastic groups. Our analysis indicates that behavioral and evolutionary mechanisms will be critical in allowing ectotherms to buffer themselves from extreme temperatures.

全球变暖正提升诸多生物遭遇过热胁迫的风险，不过目前学界对热耐受可塑性缓解该风险的潜力仍知之甚少。造成这一认知缺口的部分原因在于，我们对耐受可塑性变异的全球分布与类群模式缺乏了解。为解决这一关键问题，本研究利用涵盖陆地、淡水与海洋生境中的脊椎动物及无脊椎动物类群的数据集，检验了关于外温动物（ectotherm）耐受可塑性大范围变异的主流假说。与预期相悖的是，热耐受可塑性与纬度或热季节波动并无关联。不过在部分生境类型中，冷耐受可塑性与热季节波动存在相关性。此外，水生类群的耐受可塑性约为陆生类群的两倍。基于观测到的耐受可塑性变异模式，我们提出：行为可塑性（即行为体温调节）的有限潜力会推动生理性状更强的可塑性演化，这与“博格特效应（Bogert Effect）”相符。最后，我们发现所有外温动物的热耐受驯化程度均相对较低，并证实：即便在可塑性最强的类群中，热驯化也只能极小程度降低过热风险。本研究分析表明，行为与演化机制将是外温动物抵御极端温度胁迫的关键所在。