Yellow dog coats come from an ancient canine that split off from wolves millions of years ago
A recent genetic analysis of dog coloring revealed that mutations in one gene are responsible for five distinct coat patterns in dogs. These patterns show up in iconic breeds like the Corgi and Bernese Mountain Dog, and a team of researchers was even able to trace a type of coat, called dominant yellow, to an extinct canid that split off from Pleistocene wolves some time ago. 2 million years.
“As we think about all these coat color variations in dogs, some of them happened long before ‘dogs’ were dogs. Genetics turns out to be much more interesting because it tells us something thing about canid evolution,” said Danika Bannasch, a geneticist at the University of California, Davis, in a 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 didn’t, Bannasch’s team looked at eight still-living species, including domestic dogs and wolves. These two species produce two different types of pigments: eumelanin (black) and pheomelanin (yellow). These pigments can create five types of coat patterns in dogs, based on mutations unique to an individual dog: dominant yellow, shaded yellow, agouti, black saddle, and black back. You can see how they manifest in different breeds below. (Other coat types exist, such as solid black or solid brown, but these are not covered by this search.)
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 hair that alternates dark and light colors. The agouti gene controls the distribution of black pigment on 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.
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 ended up in dogs due to a divergence in the evolutionary tree over 2 million years ago. even before modern wolves appeared. The dominant yellow coat is found in many breeds, including Irish Terriers, Bull Mastiffs, Shiba Inus, Chow Chows, Sloughis, Basenjis, and Rhodesian Ridgebacks.
When you consider that the domestication of dogs only dates back around 30,000 years, likely a more recent timestamp than the Neanderthals’ 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 domestic dogs may have looked like.