CAREER: Linking macroecology and traits to predict mycorrhizal fungal dispersal

Plants rarely live in isolation. In fact, all plants on Earth live in close association with diverse microorganisms that greatly impact plant health. As a result, the microbial communities that associate with plants can have large implications for agriculture, forestry, and ecosystems. Mycorrhizal fungi are among the most common beneficial fungi, mining soil nutrients and delivering them to plants in exchange for sugars. However, the impact they have on plants depends on the type of fungal species present. Environmental factors and dispersal determine microbial community structure, but little is known about how microbes disperse long distances. This CAREER award combines multiple approaches using data science, laboratory, and large-scale field experiments at the National Ecological Observatory Network (NEON) to study fungal dispersal. This proposal will involve high school students in science activities and improve graduate education in ecological data science. Finally, this project will study barriers that limit the participation of minority students in ecology to develop recommendations to improve recruiting and retention.<br/><br/>For nearly 100 years, the "everything is everywhere" hypothesis has dominated microbial ecology, suggesting that microbial dispersal is unlimited and community assembly mechanisms are primarily deterministic. However, certain fungi vary with respect to traits that could impact their long-distance dispersal capabilities. Coupling knowledge of traits with physical laws that govern movement could provide a powerful framework to predict dispersal, a key component of biogeography. Arbuscular mycorrhizal (AM) fungi form no aboveground structures, and reproduce via asexual spores with substantially varying traits (e.g. size, surface ornamentation) that are likely to impact long-distance dispersal. The mechanisms and extent of AM fungal dispersal are poorly understood, yet, to manage AM fungal communities for improved symbiotic functioning, taxon-specific information regarding dispersal capabilities is required. This study combines trait-based ecology, macroecology, and physical laws to study aerial dispersal of AM fungi through the following research objectives: 1. Create an AM fungal trait database to examine conservatism among phylogenetic groups in all spore traits that potentially facilitate aerial dispersal, 2. Examine community structure and spore traits of aerial AM fungi at NEON sites and Chicago urban sites to identify eco-climatic properties that predict aerial dispersal, and 3. Compare the observed terminal velocity to that predicted by Stokes's Law for movement of a smooth sphere for AM fungal spores with different morphological traits. This CAREER award will illuminate the thus far speculative role of dispersal in driving continent-scale patterns in microbial biogeography.<br/><br/>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.