Adaptation of tropical legumes of the genus Erythrina to pollinators

In angiosperms, flowers exhibit an incredible phenotypic diversity. Their form varries tremendously from one species to another and often reflects the diversity of pollinators; plants tend to adapt in order to maximize the transfer of pollen. We studied the tropical genus Erythrina, that belongs to the legume family, as a model to better understand the evolution of floral form in response to the selection pressures of pollinators. This genus contains 131 species pollinated mainly by birds (hummingbirds and passerines) and bees. Pollination by bees and passerines, considered as the ancestral state, is associated with open flowers, while pollination by hummingbirds has likely evolved more recently. In this project, the shape of the flowers was characterized using geomorphometrics of herbarium specimens, and their evolution was inferred with a molecular phylogeny. Our results show that pollination by hummingbirds has emerged independently several times during evolution, and is accompanied by a series of similar adaptations, such as tubular flowers. This suggests that hummingbirds exert a strong selection pressure, and that the phenotype tends to converge towards a very specific floral form.

Funding source: NSERC, Mutua Madrileña Fund (Madrid, Spain)

Anne Bruneau, Simon Joly, Gonzalo Bilbao Gómez-Martino

Added by: Sébastien Renaut 2017-03-27