Shedding light on the evolution of plasticity in natural populations

Abstract

Plasticity allows for changes in phenotype in response to environmental cues, often facilitating local adaptation to seasonal environments. Phenotypic plasticity alone, however, may not always be sufficient to ensure adaptation to new localities. In particular, changing cues associated with shifting seasonal regimes may no longer induce appropriate phenotypic responses in new environments (Nicotra etal. 2010). Plastic responses must thus evolve to avoid being maladaptive. To date, the extent to which plastic responses can change and the genetic mechanisms by which this can happen have remained elusive. In this issue of Molecular Ecology, Blackman etal. (2011a) harness natural variation in flowering time among populations of the wild sunflower, Helianthus annuus, to demonstrate that plasticity has indeed evolved in this species. Remarkably, they are able to detect changes in gene expression that are associated with both a loss of plasticity and a reversal of the plastic response. These changes occur in two separate, but integrated, regulatory pathways controlling the transition to flowering, suggesting that complex regulatory networks that incorporate multiple environmental and developmental cues may facilitate the evolution of plastic responses. This study leverages knowledge from plant genetic models to provide a surprising level of insight into the evolution of an adaptive trait in a non-model species. Through discoveries of the roles of gene duplication and network modularity in the evolution of plastic responses, the study raises questions about the degree to which species-specific network architectures may act as a constraint to the potential of adaptation.