Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America.|Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America.|Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.|Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.|Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America.|Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America.