Allison Louthan

Ph.D. Student

Contact Information

Secondary Core Area


B.A., Grinnell College 


Species distributions are determined by both abiotic stress and biotic interactions, but the relative importance of these factors in constraining species' geographic ranges is poorly understood. Allison's research tests the long-standing hypothesis, first proposed by Darwin, that abiotic stress more commonly sets geographic range limits in stressful areas, but biotic interactions more commonly set limits in less stressful areas. She uses a model plant species that occurs across a pronounced aridity gradient in East Africa to test the relative strength of three key biotic interactions (herbivory, pollination, and plant-plant interactions) for population dynamics.