Hybrid Mimulus flowers attract a new pollinator

Abstract

Hybridization is common in flowering plants and is believed to be an important force driving adaptation and speciation. The hybrid flowers often have new trait combinations, which, theoretically, could attract new pollinators. In this study, we found that the hybrids between a hummingbird-pollinated species Mimulus cardinalis and a self-pollinated species Mimulus parishii attract bumblebees (Bombus impatiens), a pollinator not attracted to either of the progenitor species. This novel attraction is explained by several floral traits in hybrids, including petal color, nectar concentration, and corolla size. We also found that the YUP locus, previously shown to be important in bee attraction in other Mimulus species, also played an important role in this novel attraction. Hybrid plants attraction to new pollinators could be an underexplored avenue for pollinator shift and speciation.