Urbanization as a driver of changes in mutualistic networks between bees and plants

Urbanization is a major driver of species decline, which in turn disrupts the ecological interactions in which they are involved. Plant-pollinator networks are foundational to ecosystem productivity, and the disruption of these relationships has significant ecological consequences across multiple levels. Considering the potential of network studies to enhance our understanding of community ecology, we aim to explore how urbanization affects plant-bee interactions and the topological structure of its network. We focused on plant-bee interaction data from 10 sites along an urban gradient in southern Brazil. Data was collected by sampling bees on flowers with entomological nets over 10 months between 2017 and 2018. We analyzed two landscape variables associated with urbanization—vegetation cover and landscape diversity— and their influence on some species-level metrics (specialization – d’; connectivity among and within modules – c and z) and network metrics (specialization – H’; modularity – Q; nestedness – NODF). We found no significant relationship between the urbanization variables, species metrics, and modularity. However, sites with lower landscape diversity exhibited more specialized and nested networks. This could be due to the increased availability of resources in more diverse landscapes, leading to greater plant species sharing among bee communities and enhanced interactions with network specialists. Our findings highlight the importance of considering landscape diversity and its role in shaping ecological networks, particularly in urban environments.