DISSERTATION RESEARCH: Metabolic Bet Hedging as an Explanation for Maintenance of Diverse Tree-Ectomycorrhizal Mutualisms

Stanford University, Stanford CA

Investigators

Abstract

Many plants rely on mutually-beneficial interactions with below-ground fungi called mycorrhizae that gather nutrients, supply water, and defend against pests in exchange for energy provided by the plant. An individual plant may host dozens of different species of mycorrhizae simultaneously, including species that appear to be of little to no benefit, or may be harmful. This project proposes the idea of metabolic bet-hedging to account for the diverse array of mycorrhizae maintained by individual trees. Because trees experience marked seasonal and interannual environmental variation, their nutrient requirements also vary over time, potentially altering the relative value of each fungal partner. As human investors maintain a portfolio of stocks to compensate for economic variation, trees may maintain a range of ectomycorrhizae to respond to changing environments. This project tests the metabolic bet hedging hypothesis using a combination of laboratory experiments and mathematical models. Results from this study will be of direct value to the management of Douglas fir, the tree species targeted in this study, which is both a commercially important forestry species and an aggressive invader in some foreign locales. Both undergraduate and high school students will participate in the project, receiving valuable training in the scientific method.