Plant-pollinator-microbe interactions and climate change: Community variation along an elevational gradient

Floral nectar harbors a community of microbes that affect plant and pollinator fitness. These communities are influenced by abiotic factors, such as temperature, suggesting that climate change will alter plant-pollinator interactions by multiple mechanisms. In this study we examine the effects of increased temperature on Penstemon heterophyllus nectar using a natural elevation gradient. We collected nectar and observed pollinator visitation along an elevational gradient in order to characterize nectar-inhabiting microbial communities, nectar sugar concentrations, and pollinator communities. Nectar microbes and nectar sugars shifted along this elevational gradient. To our knowledge, we are the first to show that pollinator and nectar-inhabiting microbial communities were correlated along an elevational gradient as well. These results suggest that elevated temperatures caused by climate change may influence the interplay between the nectar microbes, nectar properties, and pollinators, ultimately having negative effects on plant and pollinator communities.