'Wolf DNA' Lurks in Many Modern Dog Breeds

"At the whole genome level, canines and wolves are clearly separated. However, when the research team constructed phylogenetic trees for each of the 1,582 genes, they found that not a single gene supported the monophyly of dogs. Further examination of the mitochondrial DNA and Y-chromosome phylogenetic trees revealed a complex interplay between canine and wolf lineages. This discrepancy is evidence of multiple rounds of gene transfer in the past."

"The researchers found that wolf genes are linked to a variety of dog traits, most notably body size. Larger dogs tend to have more wolf ancestry, and certain working breeds, such as Arctic sled dogs, wild-dog breeds, and hunting dogs, are more likely to have this trait. Terriers, bird dogs , and scent hounds, on the other hand, were least influenced by wolf genes."

"Notably, among large service dogs, the influence of wolf ancestry varied greatly among breeds. The Sarabi Dog, Central Asian Shepherd Dog, and Anatolian Shepherd Dog, which are livestock guard dogs from Turkey and Central Asia, inherited 0.5-1.2 percent of their genes from wolf ancestors, while Neapolitan Mastiffs, Bull Mastiffs, and St. Bernards showed almost no trace of wolf ancestry On the other hand, even the Chihuahua, the world's smallest dog breed, was found to have a small proportion of wolf ancestry, about 0.2 percent."

Canines and wolves separate at the whole-genome level, yet individual gene phylogenies show no single gene supporting dog monophyly, and mitochondrial and Y-chromosome trees reveal complex lineage mixing, indicating multiple historical gene transfers. Wolf-derived alleles associate with many dog traits, most strongly with body size: larger dogs and certain working breeds (Arctic sled dogs, wild-dog breeds, hunting dogs) show higher wolf ancestry, while terriers, bird dogs, and scent hounds show less. Some livestock guardian breeds carry 0.5–1.2% wolf ancestry; some mastiffs show almost none; even Chihuahuas carry about 0.2%. Breeds with fewer wolf genes appear friendlier and easier to train, while breeds with stronger wolf ancestry tend to be more suspicious of strangers.

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