Heat tolerance in ectotherms scales predictably with body size
Heat tolerance in ectotherms scales predictably with body size
复制标题
变温动物的耐热性与体型成正比
作者：
Ignacio Peralta‐Maraver;E. Rezende
最近的研究表明，动物的体型正在缩小，这是对全球变暖的普遍反应，原因尚不清楚。在这里，通过分析考虑热挑战的强度和持续时间的外温死亡时间曲线，我们表明耐热性随大小而变化。体型较小的动物比体型较大的动物可以在短时间内保持较高的体温，但不能长期保持较高的体温，因为它们的耐力随着时间的推移下降得更快。体型效应和耐热性的适应性变化在过去可能被这些无法解释的时间效应所掩盖。随着体型的增加，相对于在非应激温度下休息时，热死亡发生的代谢率相对较低，这可能部分解释了报告的随着气候变暖而导致生物体大小减少的原因，并阐明了缩放背后的机制。在挑战强度和持续时间的背景下，分析外温热死亡曲线表明，较小的动物对急性应激表现出较高的耐受性，但对慢性应激的耐受性较低。这种大小相关的影响为气候变暖导致的动物体型减少提供了一种解释。
Recent studies suggest that animals are decreasing in size as a general response to global warming, for reasons that remain unclear. Here, by analysing ectotherm death time curves that take into consideration the intensity and duration of a thermal challenge, we show that heat tolerance varies predictably with size. Smaller animals can maintain higher body temperatures than larger ones during short periods, but cannot maintain higher body temperatures over long periods as their endurance declines more rapidly with time. Body size effects and adaptive variation in heat tolerance may have been obscured in the past by these unaccounted for temporal effects. With increasing size, thermal death occurs at relatively lower metabolic rates with respect to rest at a non-stressful temperature, which might partly explain the reported reductions in organism size with climate warming and shed light on the mechanisms that underlie scaling. Analysis of ectotherm thermal death curves in the context of both challenge intensity and duration shows that smaller animals exhibit higher tolerance to acute stress, but lower tolerance to chronic stress. The size-dependent impact provides one explanation for warming-related reductions in animal size.