The Japanese wolf is more closely related to the ancestor of dogs than any other wolves found so far, according to a study that sequenced the genomes of nine museum specimens of the species, which went extinct more than a century ago.
“I did not expect this conclusion at all,” says Yohey Terai at the Graduate University for Advanced Studies in Japan.
It has long been clear that dogs evolved from grey wolves, but no living wolves are particularly closely related. So the prevailing hypothesis is that dogs evolved from a now-extinct group of wolves. But which ones and where?
The Japanese wolf (Canis lupus hodophilax) was a subspecies that was smaller than most grey wolves. The last recorded one was killed in 1905, but several museums in Japan and Europe have specimens. This meant Terai and his colleagues could get tissue samples, mostly of bones, from which DNA could be extracted.
Comparisons of these genomes with those of other wolves and dogs showed that the Japanese wolf sits on a distinct evolutionary branch of wolves that arose 20,000 to 40,000 years ago. Some of these wolves evolved into Japanese wolves while others gave rise to dogs.
This split most likely happened in East Asia, suggesting this is where the direct wolf ancestor of dogs lived. Terai hopes to extract DNA from ancient wolf bones found in this region to confirm this, but the preservation of DNA in such old bones is likely to be poor, he says.
Even if it is confirmed that the wolf ancestor of dogs lived in East Asia, this doesn’t necessarily mean that dogs were domesticated there, he says.
“It is not possible to determine when the dogs began to have a relationship with humans from the genome data,” Terai says. For this, archaeological evidence is required.
The genomes also show that after the initial split, there was some interbreeding between the Japanese wolf lineage and early dogs. This must have happened at least 10,000 years ago, because 2 per cent of the genome of a 10,000-year-old sled dog derives from Japanese wolves. This interbreeding is likely to have occurred before the wolves reached Japan, the team thinks.
Dingoes and New Guinea singing dogs have the highest amount of Japanese wolf DNA – around 5.5 per cent.
Reference: bioRxiv, DOI: 10.1101/2021.10.10.463851
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