Global drivers of invasive and native plant niche breadth within plant-floral visitor interaction networks

Plant invasions are of major ecological concern due to their negative effects on local communities, posing a threat to native plant diversity through competition for resources. Particularly, invasive species' impacts on plant-pollinator interactions can have important consequences for native plant fitness, as well as exert neutral or facilitative effects on these mutualistic interactions. The niche breadth, understood as the variety of resources used by a species, can be related in this case to the magnitude and direction of invaders' impacts on recipient plant communities. However, a comprehensive understanding of which factors shape the invasive plants' niche breadth globally remains limited. To address this gap, we investigated the global drivers of invasive and native plants' niche breadth based on two complementary metrics. To do that, we compiled a global dataset of weighted plant-floral visitor interaction networks that included invasive plants and estimated species specialization (d') and normalized degree for invasive and native plants. Moreover, we assessed the influence of climate and geographical factors on both metrics using LMM models. Our results revealed that temperature, precipitation, insularity, and latitude emerged as key predictors of specialization, and that temperature, latitude, and web intensity shaped the normalized degree for both plant groups. However, invasive status did not have a significant effect on either niche-breadth metric, and no interaction with the other drivers turned out to be significant. Our findings highlight the strong influence of environmental and geographical factors on plants' niche breadth; this is especially relevant considering the current climate change context.