Abstract: Spatiotemporal variations in plant-pollinator interactions drive floral evolution and shape the diversity of flowers in angiosperms. However, the potential role of plant-pollinator interactions in driving floral differentiation across flowering times within a population has not been documented. In this study, we aimed to quantify the variations in pollinator-mediated selection of floral traits across different flowering times of Primula sikkimensis (an entomophilous plant) in two natural populations. The results demonstrated that plants were shorter and produced fewer flowers with larger sizes in the early flowering time than in the late flowering time. In early flowering time, pollinator types were fewer and visitation frequency was lower than in late flowering time, resulting in lower female fitness. Pollinator-mediated selection of floral traits varied with flowering time, and more floral traits received pollinator-mediated selection during early flowering time. These results highlight that temporal variation in plant-pollinator interactions may have a potential role in driving floral diversification within the population.

Key words: floral evolution, flowering time, pollinator-mediated selection, Primula sikkimensis, temporal variation