UC Riverside

Floral nectar harbors a community of microbes that affect plant and pollinator fitness. Dynamic and complex plant-pollinator-microbe interactions are likely to be influenced by a rapidly changing climate, as each have their own optimal growth temperatures and phenological responses to environmental triggers, such as temperature. As pollinators forage, the microbes they inoculate into the nectar can alter nectar properties including volume and chemistry. Through a combination of 16S rRNA gene sequencing, quantitative PCR, culturing, manipulative lab and field studies, and large-scale ecological research I attempt to establish the effects of climate change on plants, pollinators, and their associated microbes. In a lab experiment, for Chapter 1, I demonstrated that the common eastern bumble bee, Bombus impatiens, prefers nectar inoculated with microbes but incubated at a non-climate change induced temperature. Next, I used a passive-heating technique (Chapter 2), and an elevational gradient (Chapter 3), to assess the influence increased temperature had on the nectar of Penstemon heterophyllus. In Chapter 2, I established that extreme temperature events influence nectar microbes more than small incremental temperature changes. I later found, in Chapter 3 that nectar microbial communities do shift along an elevational (temperature) gradient, but the implications of this shift on pollinators is dynamic and complex. This research reveals that climate change can affect pollinator networks in ways not previously described and leads to better understanding of how to best conserve our plants and pollinators.