Why do Siberian dogs have blue eyes?

Blue eyes are not common in dogs, but the Siberian is a special case. The reasons

Humans have exercised selection in dogs since the primitive domestication of the wolf. It is known that first there was a separation of the wolves population, a true natural selection, and on the closest group the human being exerted a selection pressure according to his needs and designs.

This intense artificial selection continued to occur until the formation of the most modern breeds.

This process by which the human being seeks certain favorable characteristics can drag other undesired characteristics linked to it, such as blue eyes or brown eyes in an excessively high proportion.

Through the largest study carried out on some characteristics of the canine genome to date, it has been possible to know the reason why Siberian Huskys have blue eyes. In dogs, blue eyes are very common and sought after in the Siberian Husky, a sled-pulling breed from northern polar latitudes.

Current knowledge about the genetic causes of the appearance of blue eyes in other breeds of dogs was not enough to explain the same phenomenon in Siberians. Studying thousands of dogs and their physical appearance, the phenotype, through the data provided by their guardians, they were able to correlate with eye color.

They discovered that chromosome 18, which plays an important role in mammalian eye development, was strongly associated with variation in blue eye color in Siberians and Australian Shepherds. Analysis of the DNA of more than 6,000 dogs, based on data provided by the guardians, has shown that it is due to a duplication of chromosome 18.

Just one copy of the variant is enough to cause blue eyes or heterochromia, blue and brown eyes at the same time, in many of the individuals studied.

However, some dogs with the presence of this variant did not have blue eyes, so the researchers hypothesize that there are other genetic or perhaps environmental factors that could be involved in the expression of this phenotype.

Future studies on this mechanism may lead to the discovery of a new pathway by which blue eyes develop in many mammalian species.

On the other hand, from a much broader perspective, the results underline the importance of the data provided by the animal guardians. These discoveries benefit breeding efforts and the well-being of dogs in the first place, but are also valuable for drawing conclusions in human studies, since we have many common physical traits, behaviors, and diseases through a shared environment.