Micro-scale environmental variation amplifies physiological variation among individual mussels

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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 (Mytilus californianus), 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 approximately 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.

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Copyright © 2015 The Author(s) Published by the Royal Society. All rights reserved.

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Jimenez, A. G., Jayawardene, S., Alves, S., Dallmer, J., & Dowd, W. W. (2015). Micro-scale environmental variation amplifies physiological variation among individual mussels. Proceedings of the Royal Society B: Biological Sciences, 282(1820), 20152273. http://doi.org/10.1098/rspb.2015.2273