Data from: Micro-scale environmental variation amplifies physiological variation among individual mussels

The contributions of temporal and spatial environmental variation to physiological variation remain poorly resolved. Rocky intertidal zone populations are subjected to thermal variation over the tidal cycle, superimposed with micro-scale variation in individuals’ body temperatures. Using the sea mussel (<i>Mytilus californianus</i>), we assessed the consequences of this micro-scale environmental variation for physiological variation among individuals, first by examining the latter in field-acclimatized animals, second by abolishing micro-scale environmental variation via common garden acclimation, and third by restoring this variation using a reciprocal outplant approach. Common garden acclimation reduced the magnitude of variation in tissue-level antioxidant capacities by ~30% among mussels from a wave-protected (warm) site, but it had no effect on antioxidant variation among mussels from a wave-exposed (cool) site. The field-acclimatized level of antioxidant variation was restored only when protected-site mussels were outplanted to a high, thermally stressful site. Variation in organismal oxygen consumption rates reflected antioxidant patterns, decreasing dramatically among protected-site mussels after common gardening. These results suggest a highly plastic relationship between individuals’ genotypes and their physiological phenotypes that depends on recent environmental experience. Corresponding context-dependent changes in the physiological mean-variance relationships within populations complicate prediction of responses to shifts in environmental variability that are anticipated with global change.

环境的时空变异对生理变异的贡献机制至今仍未得到充分解析。潮间带岩礁生境中的种群会经历潮汐周期内的温度波动，同时还会受到个体体温微尺度异质性的影响。本研究以加州贻贝（Mytilus californianus）为实验材料，探究此类微尺度环境变异对个体间生理变异的影响，具体通过三步开展：首先对野外适应的个体开展生理变异检测；其次通过同质园驯化（common garden acclimation）消除微尺度环境变异；最后采用互惠移植实验法恢复该环境变异。同质园驯化可使来自防波保护（温暖）生境的贻贝的组织抗氧化能力变异幅度降低约30%，但对来自波浪暴露（凉爽）生境的贻贝的抗氧化能力变异无显著影响。仅当防波保护生境的贻贝被移植到热胁迫强度较高的生境后，其抗氧化能力变异才会恢复至野外适应状态下的水平。机体耗氧速率的变异模式与抗氧化能力的变异模式一致，经同质园驯化后，防波保护生境贻贝的耗氧速率变异显著降低。上述结果表明，个体基因型与其生理表型之间存在高度依赖于近期环境经历的可塑性关联。种群内部生理特征均值-方差关系的此类情境依赖性变化，使得预测全球变化背景下环境变异改变对种群的影响变得更为复杂。