Grain of environment explains variation in the strength of genotype × environment interaction.
Theory predicts that genetic variation in phenotypic plasticity (genotype × environment interaction or G × E) should be eroded by selection acting across environments. However, it appears that G × E is often maintained under selection, although not universally. This variation in the presence and strength of G × E requires explanation. Here I ask whether the explanation may lie in the grain of the environment at which G × E is expressed. The grain (or grain size) of the environment refers to the scale of environmental heterogeneity relative to generation time - that is, relative to the window of operation of selection - with higher rates of heterogeneity occurring in finer-grained environments. The hypothesis that the grain of the environment explains variation in the expression of G × E encapsulates variation in the power of selection to shape reaction norms: selection should be able to erode G × E in fine-grained environments but lose its power as the grain becomes coarser. I survey studies of G × E in sexual traits and demonstrate that the strength of G × E varies with the grain of the environment across which it is expressed, with G × E being stronger in coarser-grained environments. This result elucidates when G × E is most likely to be sustained in the reaction norms of fitness-related traits and when its evolutionary consequences will be most pronounced.
Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA. rafa@uwm.edu
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Rodríguez
D000222:Adaptation, Physiological; D005075:Biological Evolution; D004777:Environment; D059647:Gene-Environment Interaction; D056084:Genetic Fitness; D014644:Genetic Variation; D016014:Linear Models; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic; D013997:Time Factors