Pollinator-dependent evolution of floral trait combinations in an orchid herb

Abstract

Abstract Aims As one of the most important agents driving floral evolution, pollinators shape the diversity of flowers in angiosperms. However, most previous studies have only quantified pollinators driving the evolution of a single floral trait, and experimental estimates of the potential role of pollinators in shaping the evolution of floral trait associations are relatively rare. Methods We experimentally identified and estimated the pollinator-mediated directional and correlational selection on single floral traits and trait combinations across 2 years in an orchid species, Spiranthes sinensis. Important Findings Pollinators mediated directional selection for an earlier flowering start date and larger corolla size. Pollinators mediated positive correlational selection on the combinations of floral display traits and negative correlational selection on the combinations of flowering phenology and floral display traits. In addition, the strength of selection differed over time. Our results highlight the potential role of pollinators in driving the evolution of floral trait combinations and suggest that it is necessary to consider floral character functional associations when seeking to understand and predict the evolutionary trajectory of flowers in angiosperms.