Adaptive Phenotypic Plasticity for Life History and Less Fitness-Related Traits

Abstract

Organisms are faced with variable environments and one of the most common solutions to cope with such variability is phenotypic plasticity, a modification of the phenotype to the environment. These modifications influence ecological and evolutionary processes and are assumed to be adaptive. The assumption of adaptive plasticity allows to derive the prediction that the closer to fitness a trait is, the less plastic it would be. To test this hypothesis, we conducted a meta-analysis of 213 studies and measured the plasticity of each reported trait as coefficient of variation (CV). Traits were categorised according to their relationship to fitness into life-history traits (LHt) including reproduction and survival related-traits, and non-life-history traits (N-LHt) including traits related to development, metabolism and physiology, morphology and behaviour. Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity did not correlate with its proximity to fitness. These findings were independent of taxonomic groups or environmental types assessed and raise questions about the ubiquity of adaptive plasticity. We caution about generalising the assumption that all plasticity is adaptive with respect to evolutionary and ecological population processes. More studies are needed that test the adaptive nature of plasticity, and additional theoretical explorations on adaptive and non-adaptive plasticity are encouraged.