The big, shaggy dogs of the Himalayas are 50 percent more efficient at transporting hemoglobin than lowland pooches
In the mountains, Tibetan mastiffs dare to tread wherever alternative pups would drop their screaky toys and whimper with exhaustion. the large, 150-pound animals thrive at high altitudes, and currently researchers apprehend why: the mastiffs have a bit further dose of wolf in their genes.
The big, hairy dog breed with a lion-like mane could initiate as way as one,100 B.C., once it began its role as a high-altitude working dog. Tibetan folks have used mastiffs guard their flocks of sheep from predators, like wolves, for hundreds of years. The dogs lived aboard their human companions at altitudes of fifteen,000 feet or higher, heights during which average dogs wouldn’t stand up to the dearth of O.
Researchers knew that at one purpose the mastiff interbred with a Tibetan taxon of Canis lupus as a result of the 2 share a alteration that doesn't seem within the ordering of alternative dog breeds. Rafi Letzer at Live Science reports that it absolutely was unclear what the amino acids coded by those genes really did, however researchers did suspect it absolutely was associated with their high-altitude superpowers.
In a new study revealed within the journal biology and Evolution, a team examined the mastiff’s hemoprotein design, finding that the macromolecule on red blood cells that transports O is regarding fifty % additional economical in Tibetan mastiffs than in alternative dog breeds.
“At altitude, the problem is taking in oxygen, because there’s just less of it,” says the study’s author Tony Signore, a biologist at the University of Nebraska-Lincoln, in a press release. “If you think of hemoglobin like an oxygen magnet, this magnet's just stronger.”
The story of the hemoglobin-boosting gene, however, is a little more complicated than the normal course of natural selection. In the distant past, wolves had the genes for the boosting hemoglobin, but they were pseudo-genes, meaning the weren’t expressed in their genome. So, even though the genes were present, they weren’t active and therefore didn’t give the wolves any high-altitude advantages.
At some point, the hemoglobin pseudo-genes were copied and pasted into one of the wolf’s active genes. That changed the way its hemoglobin worked, helping the Tibetan wolf become a high-altitude specialist, an advantage that was passed down to future generations.
In fact, these changes, along with mitochondrial DNA and other genetic markers have convinced some zoologists that the Tibetan wolf and other wolf populations in the Himalayas should be classified as a separate species from the gray wolf. It’s believed this new Himalayan wolf diverged from other gray wolf subspecies around 700,000 years ago.
At some point, the wolf interbred with a domestic dog breed, passing along the unique mountaineering gene that persists in the Tibetan mastiff to this day.
For the research team, the exciting part is the pseudo-gene coming to life after being dormant for generations. “[The genes] wouldn’t have conferred any benefit under normal circumstances,” senior author Jay Storz, also of the University of Nebraska-Lincoln, says in the release. “It was just [that] this conversion event occurred in an environmental context where the increase in hemoglobin-oxygen affinity would have been beneficial. So mutations that otherwise would have been either neutral or even detrimental actually had a positive fitness effect.”
Today, the breed remains popular in Tibet, but the genetic mutation can’t protect the dogs from the modern world. Tibetan mastiffs became a status symbol in China in the 2000s and early 2010s. (In 2011, one Tibetan mastiff named Big Splash sold for a reported $1.6 million.) But the dog's popularity led to a wave of overbreeding. By 2013, Tibetan mastiffs were considered passé and many were either released into the streets and mountains or sold to processors to make leather and to line winter gloves.
Source smithsonianmag.com
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