UC Riverside

Global anthropogenic climate change presents a threat to species interactions that are the foundation of ecosystems. Mutualistic interactions between plants and pollinators are critical to the maintenance of biodiversity and are threatened directly and indirectly by climate change. Climate change-driven shifts in temperature and precipitation influence both the temporal co-occurrence of flowering and pollinator foraging as well as the cues and rewards by which plants attract pollinators. These processes act at a community level by changing the availability of partners for interaction at a given time and at an organismal level by altering the physiology and behavior of interacting partners. Each of these levels of influence could affect pollination and the critical ecosystem function that it provides. In this dissertation, I use a series of experiments to explore the community- and individual-level impacts of climate change on plant-pollinator interaction. I begin by using a large, manipulative field experiment in an alpine-subalpine system to ask how advanced snowmelt, an outcome of climate change, influences a cascade of abiotic and biotic drivers that affect pollinator visitation rates. Next, I explore how advanced snowmelt in the same system restructures the web of interactions between plants and pollinators. Finally, I use a greenhouse experiment to assess how drought – another possible outcome of climate change – influences floral traits and insect behavior, providing insights into the organism-level responses shaping pollination. Together, this work provides insights into how organism-level responses to climate change may scale up to influence plant-pollinator networks and community structure. This research indicates that climate change has the potential to reshape webs of plant-pollinator interactions by altering the cues and rewards plants offer to pollinators, by restructuring plant-pollinator interactions at a network level, and by diminishing the importance of floral communities to pollinator visitation.