Pollinator scarcity drives the shift to delayed selfing in Himalayan mayapple Podophyllum hexandrum (Berberidaceae)

The transition of a breeding system from outcrossing to selfing has been considered to be a widespread evolutionary trend in flowering plants, allowing species to colonize new habitats after long-distance dispersal. Moreover, Darwin realized that autonomous self-pollination could be an adaptation to reproduction if pollinator services were lost or extremely unpredictable. In a recent study published in AoB PLANTS, Xiong et al. tested a hypothesis that the persistence of Himalayan mayapple (Podophyllum hexandrum), an early spring flowering herb in the Himalayan region, is attributable to the transition from self-incompatibility to self-compatibility i.e. the capacity for selfing in an unpredictable pollination environment. To clarify whether automatic self-pollination is achieved by movement of the pistil as suggested in a previous study, they measured incline angles of the pistil and observed flower movement during anthesis. They found that automatic self-pollination was facilitated by petals closing and stamens moving simultaneously to contact the stigma. A scarcity of pollinators may have driven the shift to delayed selfing in Podophyllum hexandrum.