3-D pollination syndromes in Aquilegia

Flowers of the genus Aquilegia are pentamerous and have two petaloid perianth whorls, of which the inner one is spurred; nevertheless, their morphology is highly diverse. In Asia and Europe pollinators are mostly bumblebees and bees, while in North America shifts to hummingbird and hawkmoth pollination have occurred. In earlier studies, typical bee, hummingbird or hawkmoth syndromes have been inferred for Aquilegia flowers, which we can largely confirm in our re-analysis of classical pollination syndromes. However, Aquilegia species are usually visited by a number of different pollen and nectar collectors, and some species seem to exhibit in mixed pollination systems. To better understand the floral evolution through pollinator-driven selection, we use X-ray computed tomography with the aim to identify 3-dimensional shape traits possibly resulting from the adaptation to one or more pollinators. Furthermore, we are complementing the study of anthetic flowers with a comparison of floral developmental sequences, among species with different pollination syndromes to fully understand floral trait divergence at a morphological level in these pollination syndromes.