Most pet dogs carry a little wolf inside them; tiny snippets of wolf DNA that slipped into dog genomes after domestication. A new study, published in Proceedings of the National Academy of Sciences, has found that almost two-thirds of dog breeds have a small amount of wolf genes, which may have provided them with unique advantages to survive in diverse human environments.
“Our findings definitely show how low levels of gene flow between dogs and wolves have contributed to what dogs are today, regardless of where the dogs are from,” the lead author of the study, Audrey Lin, told New Atlas via email.
Previous studies have shown that modern dogs evolved through the interaction between the now extinct gray wolves and humans during the Late Pleistocene. Since this ancestral split, the genetic flow between the two is rare, even though wolves and dogs can interbreed and produce fertile offspring.
To assess the rarity of wolf-dog hybridization and measure their admixture, Audrey and her colleagues traced the evolutionary histories of 2,693 dog and wolf genomes. The team found that 64% of modern breed dogs carry some trace of wolf ancestry; meanwhile, every free-living village dog contains wolf DNA.
“Wolf ancestry correlates with traits like size, function, and personality characteristics,” Audrey told us. “The majority of dogs today have low, but detectable levels of post-domestication wolf ancestry that has shaped their evolution.”
Czechoslovakian and Saarloos wolfdogs were found to have the highest levels of wolf ancestry, between 23 and 40% of their genomes. But these wolfdogs were deliberately bred for hybridization.
Among modern breeding dogs, the genomes of the Great Anglo-French Tricolor Hounds and Shiloh Shepherd had the highest wolf admixture, around 5.7 and 2.7%, respectively. Audrey says that the Great Anglo-French Tricolor Hounds are one of the most common hound dogs, and similar hound breeds do not have anywhere close to that amount of wolf ancestry.
“We were also very surprised by this result," she told us. "We have no idea how this hound ended up with such a significant wolf legacy, unfortunately."
The study has also used breed standard personality descriptions to correlate the degree of wolf ancestry with breed traits. The team described the breeds with the greatest amount of wolf genes as “suspicious of strangers,” “independent,” and “territorial.” Meanwhile, the breeds with the lowest wolf content are more often described as “friendly,” “affectionate,” and “energetic."
The lead author was careful to point out that the results don’t prove wolf DNA causes these traits – the pattern is merely correlational and demands further work.
At the other end of the spectrum, large guardian breeds including the Neapolitan Mastiff, Bullmastiff, and St. Bernard all contained no detectable levels of wolf genes. This strangely contrasts with some small breeds which still presented traces of wolf genes, including the tiny chihuahua showing 0.2% wolf genetics.
The study has been published in the journal Proceedings of the National Academy of Sciences.
