Data from: Floral reflectance, color, and thermoregulation: what really explains geographic variation in thermal acclimation ability of ectotherms?

Adaptive phenotypic plasticity in thermally sensitive traits, that is, thermal acclimation, generally increases with increasing latitude and altitude. The presumed explanation is that high-latitude/ altitude organisms have evolved greater acclimation ability because of exposure to greater temperature fluctuations. Using a conceptual model of the thermal environment during the reproductive season, we tested this hypothesis against an alternative that plasticity is greater because of increased exposure to specific temperatures that strongly select for thermal acclimation. We examined geographic variation in floral reflectance/color plasticity among 29 European populations of a widespread perennial herb, Plantago lanceolata. In- dividuals partially thermoregulate reproduction through tempera- ture-sensitive plasticity in floral reflectance/color. Plasticity was pos- itively correlated with latitude and altitude. Path analyses support the hypothesis that the thermal environment mediates these geo- graphic effects. Plasticity declined as seasonal temperature range in- creased, and it increased as duration of the growing season shortened and as the proportion of time exposed to temperatures favoring thermoregulation increased. Data provide evidence that floral re- flectance/color plasticity is adaptive and that it has evolved in re- sponse not to the magnitude of temperature variation during the reproductive season but rather to the relative exposure to low tem- peratures, which favor thermoregulation