Phenotypic Plasticity as a Product of Selection in a Variable Environment

Phenotypic plasticity has been described by character states and by a reaction norm. In an environment that is heterogeneous with regard to a continuous environmental variable, selection on the character within each environment can be described by two models of selection on phenotypic plasticity: a model of selection on character states and a model of selection on the coefficients of the reaction norm. The two selection models are a linear transformation of each other and mathematically equivalent. The reaction norm model seems to be simpler and to give rise to more predictions. The description of genetic variation in phenotypic plasticity by the genotype-environment interaction variance is related to the reaction norm model.