Floral resource‐mediated multilayer networks: structure and pollinators' roles

Resource availability shapes interactions among free‐living species, particularly in plant–pollinator mutualisms, where the composition of floral resource types influences pollinator foraging. Bees, known for utilizing a broad array of floral resources, play a crucial role in these dynamics. However, how the structure of interaction networks vary among plants offering different types of floral resources is still poorly understood, as is the role of bee abundance and resource‐use breadth in connecting these networks. We examined plant–bee interactions in an area of the Brazilian Cerrado, focusing on nectar, pollen, and oil as floral resource types. We compared the structure of plant–bee interaction networks mediated by these floral resources and evaluated the roles of bees in connecting and enhancing the structural robustness (i.e. resistance to node loss) of the multilayer network resulting from embedding the full set of floral rewards. Unique bee assemblages were associated with each floral resource, leading to distinct network structures. Oil‐mediated interactions were more nested and generalized, while nectar‐ and pollen‐mediated networks were more modular and specialized. Alongside abundant generalist species, the network included less abundant bees that interacted with a wide range of plants offering different floral resources, contributing to multilayer structural robustness by forming interconnected cores that enhance cohesion across layers. These findings suggest that differences in plant–bee network structure arise from constraints and specificities imposed by distinct floral resource types, influencing bees' foraging decisions and interaction patterns. Beyond abundant generalist bees, those collecting different types of floral resources contribute to network robustness. Our study highlights how floral resources, bee abundance, and resource‐use breadth shape plant–bee network structure in systems with multiple floral resource types.