The taxonomy of the red and eastern wolf of the Southeastern United States and the Great Lakes regions, respectively, has been long debated, with various schools of thought advocating that they represent either unique species or results of varying degrees of gray wolf × coyote admixture.

In May 2011, an examination of 48,000 single nucleotide polymorphisms in red wolves, eastern wolves, gray wolves, and dogs indicated that the red and eastern wolves were hybrid species, with the red wolf being 76% coyote and only 20% gray wolf, and the eastern wolf being 58% gray wolf and 42% coyote, finding no evidence of being distinct species in either.
The study was criticized for having used red wolves with recent coyote ancestry, and a reanalysis in 2012 indicated that it suffered from insufficient sampling.
A comprehensive review in 2012 further argued that the study's dog samples were unrepresentative of the species' global diversity, having been limited to boxers and poodles, and that the red wolf samples came from modern rather than historical specimens.
The review was itself criticized by a panel of scientists selected for an independent peer review of its findings by the USFWS, which noted that the study's conclusion that the eastern wolf's two unique nonrecombining markers were insufficient to justify full-species status for the animal.

In 2016, a whole-genome DNA study suggested that all of the North American canids, both wolves and coyotes, diverged from a common ancestor 6,000–117,000 years ago.
The whole-genome sequence analysis shows that two endemic species of North American wolf, the red wolf and eastern wolf, are admixtures of the coyote and gray wolf.
The taxonomy of the red and eastern wolf of the Southeastern United States and the Great Lakes regions, respectively, has been long debated, with various schools of thought advocating that they represent either unique species or results of varying degrees of gray wolf × coyote admixture.
In May 2011, an examination of 48,000 single nucleotide polymorphisms in red wolves, eastern wolves, gray wolves, and dogs indicated that the red and eastern wolves were hybrid species, with the red wolf being 76% coyote and only 20% gray wolf, and the eastern wolf being 58% gray wolf and 42% coyote, finding no evidence of being distinct species in either. The study was criticized for having used red wolves with recent coyote ancestry, and a reanalysis in 2012 indicated that it suffered from insufficient sampling. A comprehensive review in 2012 further argued that the study's dog samples were unrepresentative of the species' global diversity, having been limited to boxers and poodles, and that the red wolf samples came from modern rather than historical specimens. The review was itself criticized by a panel of scientists selected for an independent peer review of its findings by the USFWS, which noted that the study's conclusion that the eastern wolf's two unique nonrecombining markers were insufficient to justify full-species status for the animal.
In 2016, a whole-genome DNA study suggested that all of the North American canids, both wolves and coyotes, diverged from a common ancestor 6,000–117,000 years ago. The whole-genome sequence analysis shows that two endemic species of North American wolf, the red wolf and eastern wolf, are admixtures of the coyote and gray wolf.
Coywolf