Two populations of wolves in the origin of dogs?

The gray wolf (Canis lupus) is the first species to give birth to a pet: the dog (Family dogs). But there are many more missing pieces to put together the puzzle: where do these wolves live, which our ancestors relied on? And when? An international study, involving 38 different institutions in 16 countries and published on June 29, 2022 in the journal NATUREraised a corner of the curtain on the story of this animal which led to a unique association between humans and other species.

“There is no consensus on when, where and how”

The gray wolf roams most of the northern part of the world “for several hundred thousand years and, unlike many other large mammals, it did not become extinct in the late Pleistocene“, emphasizes the study. But doubts remain about the possible extinction of lupine populations, which adds to the further difficulty of the work of paleontologists. In an article by The researchLaurent Frantz, co-author of the new study, assures that “the majority of the wolf population that lived in the world more than 10,000 years ago, including the dog’s ancestor, has disappeared“. Identification of the” mother population “must be done by analysis of ancient DNA.

Then, if the scientific community agrees that the gray wolf allows the dog to breed through a mechanism of artificial selection, “there is no consensus on when, where and how it happened“, the study recalls. The first remains of the current line of dogs discovered date from 14,000 years ago and genetic data suggest that the ancestors of wolves and dogs diverged between 40,000 years and 14,000 years ago.the regions where the first dogs were spotted also did not imply places of origin“, Warn the researchers.

A 32,000-year-old wolf skull whose genome was studied. Credit: Gugma Dalén

Two scenarios that are impossible to decide between, at present

To solve this puzzle, the group sequenced 66 ancient wolf genomes from Europe, Siberia and North America, added to genomes already sequenced. Thus, in total, 72 genomes covering the past 100,000 years were used.

By studying ancient wolves that lived during the dog’s lifespan, we found that dogs were generally more closely related to ancient wolves in Asia than to ancient wolves in Europe, suggesting a process of living somewhere in the east.“, meaning of Science and the Future Anders Bergstrom, lead author of the study. And many signs seem to indicate a difference between dogs and wolves about 28,000 years ago, even if not excluding that life began before this point, the study determines.

Their discovery didn’t stop there: some dogs, especially in Africa and the Near East, received an additional genetic contribution of 20 to 60%, from another population of wolves related to the animals they came from. in the West. . “So there seem to be at least two distinct ‘source populations’ of wolves, producing two breeds of dogs today.“, the researcher continued.

Dogor, an 18,000-year-old wolf cub included in the study. Source: Sergey Fedorov

Two different scenarios can actually explain this result: an independent breeding between an eastern and western population with, then, an interbreeding between western dogs. Or one and the same way of life in the east, followed by a cross between dogs and wolves in western Eurasia. At present, it is impossible to favor one or the other of the assumptions. In addition, “none of the ancient wolf genomes we have studied appear to be true ancestors of dogs, meaning that this population of wolves has not yet been found.“More precisely, angry Anders Bergstrom.

Will we one day have a clear and accurate idea of ​​the birth of the wolf population of the origin of the dogs, and its age? “LSampling is patchy, especially in eastern Eurasia and the Middle East“, meaning of Science and the Future Morgane Ollivier, teacher at the University of Rennes 1 and a member of the ECOBIO laboratory. He gave a sample from excavations in Noyen-sur-Seine (estimated to be 8,600 years old) and extracted the genome. “We also lack older samples than analyzed in the European study, the researcher continued. So it will all depend on the future sampling effort but also on the chance of discovering new skeletons ”. But he did not lose hope that one day he would receive an answer: “We are finally looking for a‘ missing link ’but it is not impossible to discover it one day“.

Distant but closely involved population

By carefully examining the genome of ancient wolves, researchers have been able to gain an unprecedented understanding of the evolution of this species over the past 100,000 years. “We found that throughout the Ice Age, wolf populations in different parts of the world were remarkably genetically interconnected, reflecting the high mobility of these animals around the world.“, meaning of Science and the Future Anders Bergstrom, lead author of the study.

Their genomes also reveal instances of natural selection that result in the rapid spread of mutations beneficial to entire species, some of which may have contributed to its survival during severe climate change. while other large mammals became extinct. “High genetic connectivity likely helped the local wolf population avoid fragmentation and isolation from each other, and allowed new biological adaptations to easily reach the entire species.“, the researcher believes.

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