The Molecular Evolutionary Ecology of Plant Development: Flowering Time in Arabidopsis thaliana

Flowering time is a major fitness determinant of plants in seasonal habitats. In Arabidopsis thaliana flowering time is largely determined by photoperiod, vernalization, and ambient temperature, although foliar shade, water availability, and herbivory can also have an effect. There is selection on flowering time via both mortality and fruit production, and typically selection favors flowering time plasticity. Much of the variation in flowering time can be attributed to molecular variation in the genes that are responsible for sensing light and temperature, and many of these genes owe their discovery to these effects as determined by quantitative trait locus (QTL) mapping. Not surprisingly, many flowering time QTLs are environment-dependent. Molecular analyses of the genes underlying the response of flowering time to the environment provide further evidence that these genes have been repeated targets of natural selection.