Testing the Role that Biotic Interactions Play in Shaping Elevational-Diversity Gradients:  An Ecological Metabolomics Approach

Changes in biological diversity along elevational gradients represent one of the most striking and consistent patterns of life on Earth. Foundational hypotheses in ecology and evolutionary biology posit that stronger biotic interactions among host plants and specialized natural enemies (herbivores and pathogens) contribute to higher species diversity in lowland ecosystems with warmer, wetter, and less-seasonal climates. Yet, after more than 50 years, seminal hypotheses regarding the influence of natural enemies on biodiversity patterns remain largely untested at macroecological scales because of the overwhelming diversity of plant-chemical defenses. This project will overcome this obstacle using recent innovations in mass-spectrometry metabolomics that enable the study of plant-chemical ecology at the scale of species-rich ecological communities.

We will leverage long-term data from tropical-tree communities collected by the Madidi Project, a large-scale study of plant biodiversity in the Andes Mountains of South America, the most species-rich biodiversity hotspot on Earth. Using existing leaf samples from over 500 tree species that occur in 16 forest plots spanning a 2,600-meter elevational gradient in Bolivia, we will analyze leaf-chemical defenses (secondary metabolites) of each tree species in each forest plot to test the hypothesis that stronger selection by natural enemies for plant defenses at lower elevations shape gradients in plant diversity and evolution. This project will provide one of the first macroecological studies of plant-chemical ecology and the role it plays in the origins and maintenance of species diversity in a global biodiversity hotspot.

Publications

Sedio, B., Marko J. Spasojevic, Jonathan A. Myers, S. Joseph Wright, Maria D. Person, Hamssika Chandrasekaran, Jack H. Dwenger, María Laura Prechi, Christian A. López, David N. Allen, Kristina J. Anderson-Teixeira, Jennifer L. Baltzer, Norm Bourg, Buck T. Castillo, Nicola J. Day, Emily DeWald-Wang, Christopher W. Dick, Timothy Y. James, Jordan G. Kueneman, Joseph A. LaManna, James A. Lutz, Ian McGregor, Sean M. McMahon, Geoffrey G. Parker, John D. Parker, and John H. Vandermeer. (2021). Chemical similarity of co-occurring trees decreases with precipitation and temperature in North American forests. Frontiers in Ecology and Evolution 9: 679638. doi.org/10.3389/fevo.2021.679638

Research Team

Jonathan Myers, WashU (Biology) 
J. Sebastian Tello, Missouri Botanical Garden 
Nathan Muchhala, University of Missouri – St. Louis
Brian E. Sedio, University of Texas – Austin
David Henderson, WashU (PhD student)
Belen Alvestegui, University of Missouri – St. Louis (MS student)