Pollinator sharing among co-flowering plants mediates patterns of pollen transfer

Co-flowering plant species often share pollinators, which could result in interspecific pollination. Despite some evidence suggesting plant species with overlapping pollinators influence each other’s pollination, the relationship between pollinator sharing and heterospecific pollen transfer (HPT) is not well explained at the community level. Here, we sampled a plant-pollinator visitation network to calculate the degree of pollinator sharing, and we identified pollen deposition on stigmas of co-flowering species to construct a HPT network in a sub-alpine meadow in southwest China. We also analyzed floral colour using reflectance spectra to measure the flower reflectance dissimilarity between each pair species. We found that there was no pollen transfer between most species pairs with shared pollinators. A higher proportion of HPT links between plant species pairs with shared pollinators was observed than between pairs with distinct pollinators. More pollen grains were transferred from donor to recipient species with greater pollinator sharing. Flowers with more dissimilar flower colours exchanged less heterospecific pollen. Our study evaluated the effect of pollinator sharing in shaping pollen transfer patterns among co-flowering species, which may shed light on the ecological implications of plant–pollinator interactions, mediated by pollinator sharing.