Patterns and drivers of pollen co-transport networks vary across pollinator groups

Abstract

Pollen transport is an understudied process with consequences for plant reproductive success and floral evolution. Recently, pollinator bodies have been described as pollen competition arenas, with implications for plant community assembly. However, the identity, strength, and diversity of pollen competitive interactions and how they vary across pollinator groups is unknown. Evaluating patterns and drivers of the pollen competition landscape across different pollinator groups is central to further our understanding of plant coexistence mechanisms. Here, we integrate information on insect pollen loads with network analyses to uncover novel pollen co-transport networks and how these vary across pollinators. We evaluate differences in pollen load size, diversity and their phenological and phylogenetic attributes among insect groups and how these relate to body size and sex. Pollen co-transport networks revealed differences in the number and identity of competitors that pollen species encounter across pollinator groups. These networks were highly modular, with groups of pollen species interacting more often on pollinator bodies. Pollen load size and richness were shaped by bee size and sex. Sex also influenced the pollen phylogenetical diversity. Pollinators can impose vastly different competitive landscapes during pollen transport, with so far unknown consequences for plant reproductive success, floral evolution and community assembly.