Heather Fenton was omitted from the author list in the original version of this Article. The Acknowledgements section now reads: “We thank the wildlife professionals that contributed wolf sera, serology data, and metadata to this project: Erin Stahler, L. David Mech, Dean Beyer, Erin Largent, Susan Dicks, John Oakleaf, the Mexican Wolf Project, Lindsey Dreese, Brent Patterson, Emily Almberg, Montana Fish Wildlife and Parks, Shari Willmott, and the countless unlisted biologists that collected these samples and data through the decades. Financial support includes: E.E.B. and P.J.H. endowment from Verne Willaman; E.E.B. and P.C.C. U.S. Geological Survey (Grant G17AC00427); D.W.S., D.R.S., and D.R.M. NSF LTREB grant DEB–1245373 and many donors to Yellowstone Forever, especially Annie and Bob Graham and Valerie Gates; M.H. Parks Canada and NSF LTREB award 1556248; G.R. Pittman- Robertson Federal Aid in Wildlife Restoration Program and the State of Alaska general funds; K.B. Federal Aid in Support of Wildlife Restoration and Alaska Dept. of Fish and Game; M.A. and H.S. British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development, Habitat Conservation Trust Foundation, Forest Enhancement Society of British Columbia; D.R.M and M.A. Polar Continental Shelf Project and National Geographic Society; M.L.J.G. the Office of the Director, National Institutes of Health under award number NIH T32OD010993; T.W. Ontario Ministry of Natural Resources and Forestry; B.L.B. National Park Service; A.K. GNWT Environmental Stewardship Fund. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.” The original Article and accompanying Supplementary Information file have been corrected.