Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.|Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America.|Department of Global Health and Social Medicine, Harvard Medical School, Boston, Massachusetts, United States of America.|Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America.|Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.