CAREER: Experimental tests of competition and facilitation among migratory large herbivores from Yellowstone National Park

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A big question in ecology is: “who eats what?” Biologists need answers to this question in order to know how food webs are structured. This knowledge is what enables us to understand where species live, how they behave, and whether any disturbances to the system are liable to have adverse effects on the valuable services that nature provides to people. Yet despite working to answer this question for more than a century, researchers still struggle to identify all of the feeding links that together create the food webs of ecosystems around the world. This project focuses on the food web of Yellowstone National Park in order to understand how the diets of bison and other large mammalian herbivores are able to sustain their epic annual migrations across the ecosystem. In a collaboration with the National Park Service, undergraduates and early career researchers will track the migrations of five iconic species, monitor their foraging behaviors, and develop new types of molecular biomarkers that will enable biologists to measure animal nutrition in the wild. This CAREER project integrates real-world and classroom-based learning objectives that will advance the training of a diverse workforce capable of implementing the types of rapid diagnostic tests that are essential in modern environmental science, healthcare, and epidemiology.The research team will evaluate competing hypotheses about how seasonal changes in plant diversity and availability alter the diets of five co-occurring herbivore species: bison, elk, mule deer, bighorn sheep, and pronghorn antelope. A combination of field observations and experiments, fecal DNA metabarcoding, and an innovative adaptation of CRISPR technology for the analysis of animal nutrition will reveal: (i) how variation in animal diets feeds back to influence the structure and composition of vegetation and (ii) how different herbivore species stimulate the production of their own preferred food plants compared to the food plants preferred by other herbivores. Results will be used to parameterize a generalizable nutritional model in order to identify competition and facilitation operating in the food web. By developing, testing, and employing novel laboratory methods in combination with a series of time-tested experimental strategies in field ecology, the team aims to overcome the long-standing challenge of precisely characterizing trophic interactions in many research and training programs.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.