Washington State University, School of Biological Sciences, P.O. Box 644236, Pullman, WA 99164-4236, USA.
Washington State University, School of Biological Sciences, P.O. Box 644236, Pullman, WA 99164-4236, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2019 Dec;238:110577. doi: 10.1016/j.cbpa.2019.110577. Epub 2019 Sep 12.
Greater understanding of physiological responses to climate change demands deeper comprehension of the causes and consequences of physiological variation. Increasingly, population trait means are being deconstructed into variable signals at the level of individuals. We advocate for greater consideration of such inter-individual physiological variation and how it both depends on and interacts with environmental variability. First, we review several studies on the intertidal mussel Mytilus californianus to illustrate how the magnitude of inter-individual variation may depend on the environmental context analyzed (i.e., is the mean condition benign or stressful?) and/or on the specific physiological metric investigated. Stressful conditions may reveal or mask variation in disparate ways at different levels of analysis (e.g., transcriptome vs. proteome), but we often lack crucial information regarding the relationships among these different physiological metrics and their consequences for fitness. We then reanalyze several published datasets to ask whether individuals employ divergent strategies over time in response to acute heat stress; such time-dependence would further complicate interpretation of physiological variation. However, definitive conclusions are precluded by limited sample sizes and short timescales in extant datasets. A key remaining challenge is to extend these analytical frameworks to longer periods over which individuals in a population experience repeated, but spatially variable, episodic stress events. We conclude that variation at multiple levels of analysis should be investigated over longer periods and, where possible, within individuals (or genotypes) experiencing repeated environmental challenges. Although difficult in practice, such studies will facilitate improved understanding of potential population-level physiological responses to climate change.
要想更深入地了解气候变化对生理的影响，就必须深入理解造成生理差异的原因和后果。目前，越来越多的研究人员开始将群体特征均值进一步细分为个体水平上的可变信号。因此，我们提倡更多地考虑这种个体间的生理差异，以及这种差异如何依赖于环境变异性，又如何与环境变异性相互作用。首先，我们回顾了几项关于潮间带贻贝加利福尼亚贻贝的研究，以说明个体间差异的幅度可能取决于所分析的环境背景（即，平均条件是良性还是有压力？），以及所研究的特定生理指标。在不同的分析水平上（例如，转录组与蛋白质组），压力条件可能以不同的方式揭示或掩盖差异，但我们通常缺乏这些不同生理指标之间的关系及其对适应性的影响的关键信息。然后，我们重新分析了几个已发表的数据集，以询问个体在应对急性热应激时是否会随着时间的推移而采用不同的策略；这种时间依赖性会进一步增加对生理差异的解释难度。然而，由于现有数据集中样本量有限且时间尺度较短，因此无法得出明确的结论。一个关键的遗留挑战是将这些分析框架扩展到更长的时间范围内，在该时间范围内，种群中的个体经历重复但空间变化的偶发应激事件。我们得出的结论是，应该在更长的时间内并在可能的情况下，在经历重复环境挑战的个体（或基因型）中，对多个分析层面的差异进行研究。尽管在实践中存在困难，但这些研究将有助于更好地了解潜在的种群对气候变化的生理反应。
