As a result of the most extensive and systematic predator elimination program ever practiced by a government, the gray wolf was eradicated from the Western US and Mexico by the mid-20th century. However, this extinction, and the damage done to natural ecosystems, could conceivably be reversed through natural migration and reintroduction from surviving wolf populations in Canada.
Unfortunately, the new research indicates that the genetic diversity of historic US wolves was much greater than that of contemporaneous Canadian wolves because historic US wolves lived in an Ice Age, rich in genetic diversity. Approximately 400,000 wolves existed historically in the western coterminous US, suggesting that past ecosystems were dominated by gray wolves and were profoundly altered by their absence.
Professor Robert Wayne, one of the researchers on the project based at UCLA concludes: "Our results imply that current restoration goals of a few hundred wolves in the American West are grossly inadequate and reflect political and economic concerns rather than past biological reality".
Molecular Ecology