Temperature and the evolution of flower color: A review.

Flower colors brighten our natural world. How and why have they evolved? How might ongoing global warming alter their evolutionary trajectories? In this review, I examine the influence of ambient temperature on the evolution of flower color. Given the wide body of literature on pollinator-mediated selection, I restricted the review to temperature-mediated selection and interactions between temperature and two other abiotic factors, drought and light. I focus on flavonoid-based colors because they are widespread, and their biosynthetic pathway is well characterized. Accumulated data suggest that temperature has been a selective factor in determining large- and small-scale geographic patterns in species having genetically fixed flower color and in species with temperature-sensitive plasticity in color. However, it is also clear that we have much to learn about direct and indirect selection on flower color related to ambient temperature and temperature's contributions to phylogenetic color patterns. Therefore, I conclude with questions to help advance understanding about temperature's role in past evolution and present and future changes arising from global warming.