Intraspecific variation in key traits such as tolerance of warming can have profound effects on ecological and evolutionary processes, notably responses to climate change. The empirical evidence for three primary elements of intraspecific variation in tolerance of warming in fishes is reviewed. The first is purely mechanistic that tolerance varies across life stages and as fishes become mature. The limited evidence indicates strongly that this is the case, possibly because of universal physiological principles. The second is intraspecific variation that is because of phenotypic plasticity, also a mechanistic phenomenon that buffers individuals’ sensitivity to negative impacts of global warming in their lifetime, or to some extent through epigenetic effects over successive generations. Although the evidence for plasticity in tolerance to warming is extensive, more work is required to understand underlying mechanisms and to reveal whether there are general patterns. The third element is intraspecific variation based on heritable genetic differences in tolerance, which underlies local adaptation and may define long-term adaptability of a species in the face of ongoing global change. There is clear evidence of local adaptation and some evidence of heritability of tolerance to warming, but the knowledge base is limited with detailed information for only a few model or emblematic species. There is also strong evidence of structured variation in tolerance of warming within species, which may have ecological and evolutionary significance irrespective of whether it reflects plasticity or adaptation. Although the overwhelming consensus is that having broader intraspecific variation in tolerance should reduce species vulnerability to impacts of global warming, there are no sufficient data on fishes to provide insights into particular mechanisms by which this may occur.

中文翻译：

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鱼类对变暖耐受性的种内变异

关键性状的种内变异，如对变暖的耐受性，会对生态和进化过程产生深远的影响，尤其是对气候变化的反应。回顾了鱼类对变暖耐受性的种内变异的三个主要因素的经验证据。第一个纯粹是机械论，即耐受性在不同生命阶段和随着鱼类的成熟而变化。有限的证据强烈表明情况确实如此，可能是因为普遍的生理学原理。第二个是种内变异，这是由于表型可塑性，也是一种机制现象，可以缓冲个体在其一生中对全球变暖负面影响的敏感性，或者在某种程度上通过连续几代的表观遗传效应。尽管对变暖的耐受性具有可塑性的证据是广泛的，但还需要做更多的工作来了解潜在的机制并揭示是否存在一般模式。第三个要素是基于耐受性的可遗传遗传差异的种内变异，这是局部适应的基础，并可能定义一个物种在面对持续的全球变化时的长期适应性。有明显的本地适应证据和一些对气候变暖的耐受性的遗传证据，但知识库有限，只有少数模型或标志性物种的详细信息。也有强有力的证据表明物种内部对变暖的耐受性存在结构性变化，无论它是反映可塑性还是适应性，这都可能具有生态和进化意义。