A new study has found that most modern dog breeds have small amounts of wolf ancestry, long after dogs were domesticated.
Wolf DNA does not remain from when dogs and wolves diverged. Rather, they are most likely the result of interbreeding over the past several thousand years. That wolf-like influence may be related to specific characteristics, such as body size and personality traits, in different dog breeds, researchers reported Nov. 24 in the journal PNAS.
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Wolves and dogs genetically diverged over 20,000 years ago. Since then, a certain amount of gene flow has existed between dogs and wolves, thanks to their genetic compatibility. To measure the extent of admixture and its impact on both animals, the researchers studied the genomes of about 2,700 previously published dogs and wolves from the late Pleistocene (the last Ice Age) to the present. This group included 146 ancient dogs and wolves, 1,872 modern dogs, and about 300 “village dogs” that lived around humans but were not pets.
The researchers found that at least 264 modern dog breeds have wolf ancestors passed down through interbreeding that took place an average of 900 generations before dogs, or about 2,600 years ago. This was long after dogs were domesticated at least 20,000 years ago. The most wolf-like dog genomes contained up to 40% wolf ancestry, while most dog genomes contained 0 to 5% wolf ancestry.
“Until this study, the prevailing science seemed to suggest that for a dog to be a dog, there couldn’t be much, if any, wolf DNA present,” study co-author Audrey Lin, an evolutionary biologist at the American Museum of Natural History in New York City, said in a statement. “But when we take a closer look at the modern dog genome, we find that wolves are there. This suggests that the dog genome can ‘tolerate’ wolf DNA to an unknown degree and still remain the dog we know and love.” ”
The Czechoslovakian Wolfdog and Saarloos Wolfdog have the highest wolf ancestry, which is perhaps not surprising since they were deliberately bred in the 20th century by crossing domestic dogs with wolves. Large dogs and certain working dog breeds, such as Arctic sled dogs, hunting dogs, and certain guard dog breeds from West and Central Asia, such as the Anatolian Shepherd, tended to have higher levels of wolf ancestry.
However, many breeds did not fit these patterns. Some large guard dogs, such as bullmastiffs and St. Bernards, have no recognized wolf ancestry. Some small dogs also have small amounts of wolf-like DNA. For example, the researchers found that 0.2% of the Chihuahua’s genome can be traced back to wolves.
“This is completely understandable to anyone who owns a Chihuahua,” Lin said in a statement. “And what we’ve found is that this is the norm. Most dogs are a little bit wolfish.”
Meanwhile, scientists found that the genomes of all the “village dogs” tested contained wolf DNA. And the reason may be related to their survival. “A set of wolf DNA found in the village dog genome contained genes associated with olfactory receptors,” Lin and Kistler write in The Conversation. “We imagine that wolf genetically influenced olfactory abilities may have helped these free-living dogs survive in harsh and unstable environments.”
Some personality traits that Kennel Clubs use to describe certain breeds are also tracked, along with the amount of wolf influence. Breeds with low wolf ancestry were often described as “friendly,” “easy to train,” or “active,” while breeds with more wolf DNA were pegged as “suspicious of strangers,” “independent,” and “dignified.” It is not yet clear whether wolf genes are directly involved in these traits.
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