Recipient and donor characteristics govern the hierarchical structure of heterospecific pollen competition networks
O_LIPollinator sharing can have negative consequences for plant fitness with the arrival of foreign pollen, yet responses are often variable among species. Plant traits and relatedness of donor and recipient species have been suggested to drive the variations in plant fitness, but how they shape the structure of pollen competition networks has been overlooked at the community level. C_LIO_LITo understand the importance of traits and relatedness we conducted a controlled glasshouse experiment with an artificial co-flowering community. We performed 900 reciprocal crosses by experimentally transferring pollen among 10 species belonging to three different plant families. C_LIO_LIWe found a significant reduction in seed set for 67% of the crosses, driven largely by recipient traits and the interaction between recipient-donor traits under specific circumstances of trait-matching. These traits and their asymmetries among species led to a hierarchical (or transitive) structure of pollen competition with clear winners and losers depending on specific combination of traits. C_LIO_LIA greater understanding of the importance of trait matching and asymmetries among donor and recipient plant species will facilitate knowledge of the mechanisms underlying foreign pollen impacts upon plant reproductive fitness. This will require a shift from pairwise to community level interactions. C_LI