This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports research and training of the Fellow that will contribute to the area of Rules of Life in innovative ways. Many living things benefit each other, and these relationships often involve multiple species. Why are these interactions not specialized on a single ?best? partner? This research proposes a new Rule of Life to explain this paradox: Portfolio effects, predicting that diverse partners exist because no single partner is the ?best? under all conditions. Like investors, organisms may need a broad portfolio of relationships, in case the environment changes. This project examines portfolio effects in the ectomycorrhizal mutualism, required by roughly 60% of trees. Ectomycorrhizal plants feed sugars to dozens of fungi on their roots in exchange for nutrients and water. Since trees live for decades, they must withstand environmental variation, from winter storms to droughts. Their fungi may offer different symbiotic benefits in these environments. Thus, trees may need to maintain fungal diversity over time. This research tests for portfolio effects in seedling recruitment, to improve predictions for how forests will respond to environmental variation. This research will also train undergraduate researchers underrepresented in ecology, and will support public lectures and a science workshop for middle school students.
This project combines greenhouse experiments, gene expression analysis, and mathematical modeling to investigate portfolio effects. The Fellow will use Douglas fir and fungal cultures to understand how symbiotic fungal function varies under stress. The stressors tested ? drought and nitrogen pollution ? represent likely future environmental conditions in many forests. The Fellow will measure how well tree seedlings tolerate stress when associated with each fungus, and will measure fungal gene expression across environments, connecting genomes to phenotypes. Then, a statistical model will simulate how well a population of seedlings associated with the tested fungi would withstand a stressful growing season. Portfolio effects predict that populations of seedlings with more diverse symbionts will grow and survive more consistently. Finally, an eco-evolutionary model will examine how specialized a plant lineage will become, depending upon how frequently the environment shifts. Portfolio effects predict that variable environments should select for diverse (not specialized) associations. The Fellow will learn mathematical modeling with her mentor, and will collaborate with experts in France to enhance her metatranscriptomic analysis skills.
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.
