遺伝学：ダイアウルフは進化的に孤立したために窮地に追い込まれた

Dire wolves last shared a common ancestor with living wolf-like species approximately 5.7 million years ago, reports a study published in Nature this week. The results of the genetic analysis also suggest that this extinct species originated in the Americas, whereas the ancestors of grey wolves, coyotes and dholes evolved in Eurasia and colonized North America at a later point.

Dire wolves were a large, wolf-like species and one of the most common carnivores found in the Americas during the Late Pleistocene age (approximately 126,000 to 12,000 years ago). Owing to similarities in body shape, it is thought that dire wolves and grey wolves may have been closely related, but the precise relationship has been unclear.

To gain insights into their evolutionary history, Laurent Frantz and colleagues sequenced the DNA from five fossil dire wolf bones ranging from 50,000 to 12,900 years old. The authors found that dire wolves last shared a common ancestor with living wolf-like canines around 5.7 million years ago and diverged from African jackals around 5.1 million years ago. They also reported no evidence in their sample of gene flow between dire wolves and grey wolves or coyotes. According to the authors, this suggests that admixture was unlikely to have occurred and that dire wolves evolved in geographical isolation from the ancestors of grey wolves and coyotes.

Frantz and co-authors suggest that as dire wolves did not derive any ancestry from other wolf-like species, this may have prevented them from acquiring traits that may have aided their survival during the Late Pleistocene megafaunal extinctions.