CAREER: Testing the mismatch hypothesis for climate change-driven mutualism breakdown

In the mutually beneficial interaction between flowering plants and pollinators, plants benefit from pollen transfer among flowers, and pollinators benefit from nutrition in the form of nectar and pollen. Plant-pollinator mutualisms are essential for natural ecosystems as well as agricultural supply; about 90% of flowering plants and 35% of crop species rely on animals for pollination.

For pollination mutualisms to be maintained, plants must flower during the same time of year that their pollinators are foraging. Similarly, the traits of each partner, such as flower size and bee body size, must match. However, changing environmental conditions, such as warming temperatures, may cause mismatches in the timing of life events and the traits of flowers and pollinators, potentially leading to breakdown of the mutualism.

This research will test how environmental change affects the maintenance of plant and pollinator mutualisms, and ultimately pollination services. The proposed research will contribute to the development of a diverse, globally competitive STEM workforce and help to improve STEM education by training undergraduates at the University of California, Riverside, a Hispanic Serving Institution, in scientific inquiry.

The educational plan uses experimental plant and pollinator communities to involve hundreds of undergraduate students in data collection and interpretation at multiple points in their college careers, improving learning outcomes and advancing project research goals at the same time. The project will improve public scientific understanding by creating a pop-up outreach program that travels to Riverside neighborhoods, community centers, and parks to raise awareness about the importance of pollination services that are threatened by environmental change.

Finally, the research will advance the health of the public by informing predictions for how pollination services for natural and agricultural communities will fare under novel environmental conditions. Altogether, the results will broaden understanding of the effects of environmental change on species interactions in the scientific community, the classroom, and the public.

This project will: (1) experimentally test, for the first time, how simultaneous warming affects plant and pollinator phenology; (2) investigate how warming affects plant and pollinator morphological, physiological, and behavioral traits; and (3) measure the multigenerational effects of warming on plant and pollinator interactions and fitness. Using foraging arenas in temperature-controlled greenhouses, native wildflowers and solitary bees will be concurrently exposed to warming before flowering and emergence to measure phenological and phenotypic responses of these interdependent species over three generations.

Key aspects of the experiment will be replicated in a field setting to test how temperature-induced phenological changes affect plant-bee interactions, traits, and fitness in natural communities. The proposed project tests the hypothesis that environmental change will generate phenological mismatches between plants and pollinators and alter traits, thereby threatening an ecologically and economically critical mutualism.

The work will also provide insight into the evolutionary processes shaping plant and pollinator responses to environmental change by quantifying the phenotypic and fitness effects of different temperature treatments.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.