Tibetan mastiffs benefit from wolf genes

AWOO?

TIBETAN MASTIFFS ARE huge dogs that survive high up in the mountains, and now we know their ability to thrive in such harsh and low-oxygen environs comes from an extra shot of wolfishness in their genes. The bulky dogs, which can weigh up to 70 kilograms, are “renowned for [their] hypoxia tolerance,” according to the authors of a new study into these dogs’ genes. That means Tibetan mastiffs can thrive at high altitudes, where the thin air and low oxygen levels would kill other breeds.

According to the recent study, at some point in the past the dogs interbred with wolves. Their descendants inherited gene mutations that code for two amino acids – small pieces of a protein – that make Tibetan mastiffs’ blood better at capturing and releasing oxygen. The two tweaks alter the way the dogs and wolves produce haemoglobin, the iron-containing protein in blood that carries oxygen, the researchers revealed.

They compared haemoglobin from Tibetan mastiffs and Tibetan wolves with the haemoglobin from other domestic dogs, and discovered that Tibetan mastiffs and wolves have a significant advantage over other breeds in their ability to absorb and release oxygen in thin-air conditions.

From the genetic studies it appears that, in the distant past,

Tibetan wolves sometimes had these mutations in a stretch of dormant DNA, which didn’t code for a protein. At some point, those mutations got copied into an active gene, thereby giving the wolves altered haemoglobin.

Then, as the animals moved into higheraltitude environments, the handful of wolves that had these mutations came to dominate the species, and they became the norm. Later on, the wolves passed on the tweaked gene to Tibetan mastiffs, and those that inherited the altered haemoglobin gene came to dominate the breed.