Abstract

Animal-mediated pollination is essential in the reproductive biology of many flowering plants and tends to be associated with pollination syndromes, sets of floral traits that are adapted to particular groups of pollinators. The complexity and functional convergence of various traits within pollination syndromes are outstanding examples of biological adaptation, raising questions about their mechanisms and origins. In the genus Petunia, distinct pollination syndromes are found for nocturnal hawkmoths (P. axillaris), diurnal bees (P. integrifolia) and hummingbirds (P. exserta), with characteristic differences in petal color, corolla shape, reproductive organ morphology, nectar quantity, nectar quality and fragrance. We use QTL mapping and genetic introgression to define the major genetic loci underlying shifts in pollination syndromes and assess their effect on pollinator behavior. Using petal color as an example, I will show how polymorphisms in a single gene cause major shifts in pollinator preference. The identification of such polymorphisms at the molecular level will be important to understand how pollination syndromes evolved and contributed to the restriction of gene flow during incipient speciation.