TY - JOUR T1 - Pollinator specialization imposes stronger evolutionary constraints on flower shape JF - bioRxiv DO - 10.1101/041533 SP - 041533 AU - Simon Joly AU - François Lambert AU - Hermine Alexandre AU - Étienne Léveillé-Bourret AU - John L. Clark Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/02/26/041533.abstract N2 - Flowers show an unrivalled diversity as reproductive organs but the evolutionary forces underlying this diversity are still poorly understood. In animal-pollinated species, flower shape is fashioned by selection imposed by pollinators, which is expected to vary according to specific guilds of effective pollinators. Using the Antillean subtribe Ges-neriinae (Gesneriaceae), we tested the hypothesis that the corolla shapes of specialists effectively pollinated by one functional type of pollinator have maintained more similar shapes through time due to stronger selection constraints than those of species effectively pollinated by more than one functional type of pollinator. Using geometric morphometrics, we show that corolla shape can differentiate hummingbird specialists, bat specialists, and species with a mixed-pollination strategy (pollinated by hummingbirds, bats, and occasionally insects). Then, using evolutionary models, we show that the corolla shape of hummingbird specialists has been evolving under balancing selection, whereas a neutral model of evolution was favoured for mixed-pollination species. This suggests that the corolla shape of pollination specialists remains more similar over macro-evolutionary periods of time to remain fitted to their pollinators. In contrast, corollas of species with a mixed-pollination and thus more generalized strategy vary more, potentially because they experience effective pollination over a wider corolla shape space. ER -