Too lonely? The gigantic North American wolf, emblematic of the prehistoric megafauna of the Ice Age, disappeared 12,000 years ago without leaving a genetic trace in its contemporary cousins, which he nevertheless met, according to a study published on Wednesday .
For over a hundred years, biologists believed that “Canis dirus” – the “sinister wolf” or “terrible wolf” popularized by the “Game of Thrones” series – was a subspecies of the common gray wolf, to which it was morphologically close. although about 20% larger.
There was no shortage of studies, because the predator that roamed the North American continent for millions of years left behind fossils in abundance, especially in the Rancho La Brea deposit in California, where animal remains from the Pleistocene (geological period marked by glacial cycles) have been preserved in bitumen traps.
But these bones had not said everything, their analysis being limited to anatomy. And for the first time, an international team of researchers, whose work is published in the journal Nature, has made genetics talk.
Researchers were able to analyze DNA from 50,000-year-old remains found in Wyoming, Idaho, Ohio and Tennessee. In addition, they succeeded in sequencing collagen proteins recovered from the bones of Rancho La Brea, a biomarker allowing comparisons with other species.
Verdict: “Canis dirus” is a species apart, and only a distant cousin of “Canis lupus”, the current gray wolf. They are as far apart as humans and chimpanzees, comments Kieren Mitchell of the University of Adelaide in Australia, co-author of the study.
– Dead end –
These two species of canids had a very old common ancestor from which they would have diverged between 5 and 7 million years ago, forming two distinct lineages.
“Given their similar morphologies, we were surprised that they are genetically so different,” paleogeneticist Laurent Frantz, from Queen Mary University in London, told AFP, one of the main authors.
The “terrible wolf” would have lived in North America in autarky, completely isolated from the other species of canines which wandered through Eurasia.
The mega-carnivore thrived there on its own for millions of years, hunting the rich fauna of large mammals, such as bison, which then inhabited the northern hemisphere. Until wolves and coyotes landed from Eurasia.
With these new arrivals, it would have cohabited “for the last 20,000 years of its existence”, explains Laurent Frantz. But without reproducing, since we can no longer find any trace of the genetic material of the “sinister wolf”.
However, genetic exchanges are frequent between different species of canids occupying the same ecosystem, for example between the gray wolf and the coyote.
Such crossings have also occurred between homo sapiens and Neanderthals, of which our genome has kept traces, recalls Kieren Mitchell.
So why this lack of hybridization in the “sinister wolf”? It is possible that he married with the other species, but that a “biological barrier (no infertility), or behavioral (the children would not have been able to integrate with the packs of other species), made reproduction impossible “, advances Laurent Frantz.
“Canis diris” was thus “unable to survive through other genes”, which, for example, could have enabled it to resist “imported” diseases. And as its prey, the other large mammals, disappeared, it found itself “in an evolutionary impasse”, resulting in its total extinction, decrypts the scientist.
He was undoubtedly “too specialized”, whereas the common wolf “more” flexible “, knew how to adapt to the variations of temperature and through history.” The gray wolf is very resistant. The only thing that poses a problem for him today is man, “concludes the biologist.