Fig. 1: Evolution of plasticity in novel environments.

Phenotypic plasticity can influence the evolutionary outcome for a population colonizing a novel environment. Ancestral plasticity may move the initial phenotype of a population (x) in any number of directions with respect to the local optimum of the novel environment (adaptive peak, y). These variable responses are adaptive when they move phenotypic values directly into (A) or close to—but outside—the peak y. If sufficient genetic variation is exposed, natural selection can reinforce adaptive plasticity and move phenotypic means towards the new peak (B; dotted lines). However, natural selection is not expected when plasticity puts individuals directly onto the new peak (A). In the case of maladaptive plasticity (C), inappropriate responses to the novel environment move individuals away from the peak, reducing fitness. Selection should reduce/reverse the reaction norm and restore the phenotypic mean back to the original ancestral value. In all cases, the strength of selection increases with distance from the peak (dotted lines in B, C). Based on Fig. 2 in Ghalambor et al.⁴.