Résumé
Phenotypic plasticity is an important strategy for coping with changing environments. However, environmental change usually results in strong directional selection, and little is known empirically about how this affects plasticity. If genes affecting a trait value also affect its plasticity, selection on the trait should influence plasticity. Synthetic outbred populations of Arabidopsis thaliana were selected for earlier flowering under simulated spring- and winter-annual conditions to investigate the correlated response of flowering time plasticity and its effect on family-by-environment variance (VgXe) within each selected line. We found that selection affected plasticity in an environmentally dependent manner: under simulated spring-annual conditions, selection increased the magnitude of plastic response but decreased VgXe; selection under simulated winter-annual conditions reduced the magnitude of plastic response but did not alter VgXe significantly. As selection may constrain future response to environmental change, the environment for crop breeding and ex situ conservation programmes should be carefully chosen. Models of species persistence under environmental change should also consider the interaction between selection and plasticity.