 During this time Nelson helped to make the University of Michigan one of the United States preeminent graduate programs in ecology.Afterwards he spent 12 years as a professor at the University of North Carolina as a Kenan Professor of Biology, where he advised students including evolutionary biologist Richard Lenski.Throughout Hairston’s career, he focused most of his work on the role trophic interactions, such as the trophic cascade, has on determining the species composition of communities of co-existing organisms.