Hidden genetic variation in plasticity provides the potential for rapid adaptation to novel environments

Abstract

ABSTRACTIf genetic variation in fitness emerges in novel environments, then rapid adaptation can overcome fitness declines and allow population persistence. Although plasticity is expected to underlie such genetic variance in fitness, this has not been tested empirically. We transplanted cuttings of a Sicilian daisy (Senecio, Asteraceae) within and outside its native range, and quantified genetic variation in fitness, which we connect to plasticity in leaf traits and gene expression. Compared to native environments, mean fitness in the novel environment declined by 87%, but was associated with a threefold increase in genetic variation. Fitness in the novel environment was genetically correlated with plasticity: genotypes with greater fitness showed higher plasticity in leaf form, lower plasticity in leaf physiology and more gene underexpression. Surprisingly, genotypes with greater fitness in the novel environment had the lowest fitness at the native site. Therefore, genetic variance in plasticity increases the potential for rapid adaptation to novel environments, but adaptive plasticity and stabilising selection in native (non-stressful) environments hides such genetic variation in natural populations.