The iconic, prehistoric wolf, which roamed Los Angeles and elsewhere in the Americas more than 11 millennia ago, was a distinct species from the slightly smaller gray wolf, an international team of scientists reports today in the journal. Nature.
The study, which puts an end to a mystery that biologists have been pondering for over 100 years, was conducted by researchers at UCLA, as well as colleagues at Durham University in the UK, from the University of Adelaide in Australia and Ludwig Maximilian University in Germany.
“The terrible terrible wolf, legendary symbol of Los Angeles and the tar pits of La Brea, earned its place among the many great unique species that became extinct at the end of the Pleistocene era,” said Robert Wayne, Distinguished Professor of UCLA. of ecology and evolutionary biology and co-lead author of the study. The Pleistocene, commonly known as the Ice Age, ended around 11,700 years ago.
More than 4,000 terrible wolves have been unearthed from the La Brea tar pits, but scientists know little about their evolution or the reasons for their eventual demise. Gray wolves, also found in fossil-rich pits, have survived to this day.
“The dreaded wolves have always been an iconic representation of the last ice age in the Americas, but what we know of their evolutionary history has been limited to what we can see from the size and shape of their bones.” said co-lead author Angela Perri of Durham University.
These bones now reveal a lot more. Using cutting-edge molecular approaches to analyze five terrible wolf genomes from fossil bones dating back 13,000 to 50,000 years, researchers were able to reconstruct the evolutionary history of the long-extinct carnivore for the first time.
Significantly, they found no evidence of gene flow between terrible wolves and North American gray wolves or coyotes. The lack of any genetic transfer indicates that terrible wolves evolved independently from the Ice Age ancestors of these other species.
“We discovered that the terrible wolf is not closely related to the gray wolf. Plus, we’ve shown that the terrible wolf never crossed paths with the gray wolf, ”said co-lead author Alice Mouton, who conducted the research as a postdoctoral fellow at UCLA. researcher in ecology and evolutionary biology in Wayne’s laboratory.
The ancestors of the gray wolf and the much smaller coyote evolved in Eurasia and would have arrived in North America less than 1.37 million years ago, relatively recently in evolution. The terrible wolf, due to its genetic difference from these species, is now believed to be native to the Americas.
“When we started this study, we thought that terrible wolves were just muscular gray wolves, so we were surprised to learn how genetically different they were, so much so that they probably wouldn’t have could recur, ”the latest study said. author, Laurent Frantz, professor at Ludwig Maximillian University and Queen Mary University in the United Kingdom. “It must mean that terrible wolves have been isolated in North America for a very long time to become so genetically distinct.”
“Fearsome wolves are sometimes described as mythical creatures – giant wolves prowling in icy, dark landscapes – but the reality turns out even more interesting,” said Kieren Mitchell of the University of Adelaide, co-lead author .
The terrible wolf was a ‘lone wolf’ when it came to breeding
Interbreeding is quite common among wolf lineages when their geographic areas overlap. Gray wolves and modern coyotes, for example, are common in North America. Yet the researchers, using a dataset that included a terrible wolf from the Pleistocene, 22 modern North American gray wolves and coyotes, and three ancient dogs, found that the terrible wolf had not crossed paths with any of the others – probably because he was genetically incapable of reproducing with these species.
“Our finding that there was no evidence of gene flow between terrible wolves and gray wolves or coyotes, despite substantial range overlap in the Late Pleistocene, suggests that the common ancestor of gray wolves and coyotes likely evolved in the geographic isolation of members of the terrible wolf lineage. “Wayne said.” This result is consistent with the hypothesis that terrible wolves originated in the Americas. “
Another hypothesis about the terrible wolf – which has not been tested in the current study – concerns its extinction. It is generally believed that due to its body size – larger than gray wolves and coyotes – the terrible wolf was more specialized in hunting large prey and was unable to survive the extinction of its regular food sources. A lack of interbreeding could have accelerated his demise, suggested Mouton, now a postdoctoral researcher at the University of Liège in Belgium.
“Perhaps the terrible wolf’s inability to reproduce did not provide the necessary new traits that could have enabled them to survive,” she said.
Uncover the mystery of the terrible wolf’s DNA
While the terrible wolves sequenced in this study possessed no ancestry from gray wolves, coyotes, or their recent North American ancestors, a comparison of the terrible wolves’ DNA to that of gray wolves, coyotes, and a large variety of other wolf-like species has revealed a common but distant evolutionary relationship.
“The ancestors of the terrible wolves probably diverged from those of the gray wolves over 5 million years ago – it was a big surprise to find that this divergence happened so early,” said Mouton. “This finding highlights how special and unique the terrible wolf was.”
Based on their genomic analyzes, the researchers also concluded that there are three primary lineages that descend from common ancestry: terrible wolves, African jackals, and a group comprising all other extant wolf species, including the grey Wolf.
Gray wolves, which today mostly live in the wild and remote parts of North America, are more closely related to African wild dogs and Ethiopian wolves than to terrible wolves, Wayne noted.
The study is the first to report genome-wide data on terrible wolves.
Genomic analyzes – conducted as a joint effort at UCLA, Durham University, University of Oxford, University of Adelaide, Ludwig Maximilian University and the Queen Mary University – focused on both the nuclear genome and the mitochondrial genome, which is abundant in ancient remains.
“The decrease in the cost of sequencing assays, in addition to advanced molecular biology methods for highly degraded materials, allows us to recover DNA from fossils,” Mouton said. “Genomic analyzes of ancient DNA represent an incredible tool to better understand the evolutionary history of ancient and extinct species.”
Wolves have looked after the pack for at least 1.3 million years
The dreaded wolves were the last of an ancient New World canid line, Nature (2021). DOI: 10.1038 / s41586-020-03082-x, www.nature.com/articles/s41586-020-03082-x
Provided by the University of California, Los Angeles
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