Yellow dog coats come from an ancient canid that separated from wolves millions of years ago

A shiba inu, which has the

A shiba inu, which has the “dominant yellow” coat phenotype described in the new research.
Photo: Matt Cardy (Getty Images)

A recent genetic analysis of dog colouration revealed that mutations in one gene are responsible for five distinctive coat patterns in dogs. These patterns show up in iconic breeds like the Corgi and Bernese Mountain Dog, and a team of researchers have even been able to trace a coat type, called a dominant yellow, to an extinct canine that separated from Pleistocene wolves ago. 2 million years ago.

“While we think of all of these coat color variations in dogs, some of them happened long before ‘dogs’ were dogs. Genetics are proving to be much more interesting because they tell us something about the evolution of canids, ”said Danika Bannasch, geneticist at the University of California Davis, in a report. Press release. Bannasch is the lead author of a new study on genetic variants, published last week in Nature Ecology and Evolution.

To understand when the mutation occurred and which canids had the mutation and which did not, Bannasch’s team looked at eight living species, including domesticated dogs and wolves. These two species make two different types of pigments: eumelanin (black) and pheomelanin (yellow). These pigments can create five types of coat patterns in dogs, based on an individual dog’s unique mutations: dominant yellow, shadow yellow, agouti, black saddle, and black back. You can see how they show up in different races below. (Other coat types exist, such as solid black or solid brown, but these are not covered by this research.)

25 different dogs sorted by coat.

The different layers are produced by varying the mixtures of the two pigments, which are determined by variations in the agouti signaling protein. In this case, agouti refers to the hair that alternates between dark and light colors. The agouti gene controls how the black pigment is distributed throughout a number of mammals, including Hare, horses and mice.

The researchers found that two regions of the gene must mutate to cause the different coat color patterns. Of course, two breeding dogs can have offspring with a variety of these coat patterns, depending on the haplotypes of the parents.

A dog with a beige back and a white forehead.

Jiff the Collie, who has a yellow shadow phenotype.
Photo: Susan larson

Interestingly, the dominant yellow coat type is the oldest. The team determined that the genetic combination that produces the coat is shared with arctic white wolves and found in dogs because of a divergence in the evolutionary tree over 2 million years ago. years, even before modern wolves appeared. The dominant yellow coat is found in many breeds, including Irish Terriers, Male Mastiffs, Shiba Inu, Chow Chows, Sloughis, Basenjis, and Rhodesian Ridgebacks.

When you consider that the domestication of dogs can only be traced back to around 30,000 years ago, likely a more recent timestamp than the Neanderthal extinction, it shows how long these coat differences have been floating around. And with a sample of the team’s work dating back to a 9,500-year-old dog with a black pattern, it gives geneticists a better idea of ​​what some of the earliest domesticated dogs may have looked like.

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