His research focuses on threats to plant and animal diversity in the Great Lakes region’s forests including habitat fragmentation, overabundant deer, climate change, and invasive species. He co-authored Wild Forests: Conservation Biology and Public Policy, and co-edited The Vanishing Present: Shifts in Wisconsin’s lands, waters, and wildlife. Professor Waller is a Fellow of the American Association for the Advancement of Science, and served as an Associate Editor for Oecologia and Ecology Letters, Editor-in-Chief of Evolution, and President, Society for the Study of Evolution.