Despite the morphological similarities between grey wolves and dire wolves, the latter diverged from the living canids 5.7 million years ago. However, relatively little information is known about their evolutionary history. New research is helping to fill these gaps.
"Dire wolves are sometimes portrayed as mythical creatures, giant wolves prowling bleak frozen landscapes, but reality turns out to be even more interesting", Dr Mitchell said. A global crew of scientists, with the participation of the College of Zaragoza (Unizar), has found that they have been the final wolves of an historic lineage. These large carnivores were thus able to prey upon the many large herbivores that shared their ice age habitats. But scientists reveal that dire wolves were real once upon a time.
'With this first ancient DNA analysis of dire wolves, we have revealed that the history of dire wolves we thought we knew - particularly a close relationship to grey wolves - is actually much more complicated than we previously thought. But somehow, they reached an evolutionary dead end. "Their line and legacy disappeared forever". This makes them a distant relative of today's wolves.
The fierce dire wolves dominated the ecology of Pleistocene America. "This fact might be the reason for their extinction". Prior to the new study, researchers primarily focused on dire wolf skeletons, which, while helpful, didn't tell the whole story. However, there was no evidence that the dire wolves had interbred with coyotes or grey wolves. "Eventually we realised we all had different pieces of the puzzle and joined forces to get the best picture of dire wolf evolution that we possibly could".
The global team has sequenced the ancient DNA of five dire wolf sub-fossils from Wyoming, Idaho, Ohio, and Tennessee, dating back to over 50,000 years ago. The absence of any genetic transference indicates that dire wolves evolved in isolation from the Ice Age ancestors of these other species.
Given that other dog species appear to have engaged in near-regular crossbreeding, researchers have checked for signs of this here.
This surprised researchers as similar species, including African wolves and jackals, can and do interbreed.
Skeleton of ‘Canis dirus’ in the George C. Web page Museum. Wikipedia
When gray wolves and coyotes arrived from Eurasia, likely about 20,000 years ago, dire wolves were apparently unable to breed with them, as the researchers found no traces of genetic mixing. It seems that the lineage that led to grey wolves, coyotes, canines, and different wolf-like canids later cut up off. "Till now the two species had been thought of intently associated, some authors even thought of them to be the similar species and there was some opinion that supposedly there might be hybrids", he explains to SINC Pere Bover, co-author of the research and researcher ARAID and the College Institute for Analysis in Environmental Sciences of Unizar.
Dire wolves, made famous in the TV show Game of Thrones, were common across North America until around 13,000 years ago, after which they went extinct.
That could also mean a reimagining of what dire wolves looked like. There is a hint at the possibility that the ancestors of dire wolves mated with ancestors of wolves, coyotes, and hatchlings somewhere around 3 million years ago, but the indication for this is rather weak. They recovered about one-quarter of the nuclear genome and the full mitochondrial DNA across five individuals, ranging in age from about 13,000 to more than 50,000 years old.
"It's a fascinating study" that reveals just how distinct dire wolves were, says Robert Dundas, a vertebrate paleontologist and expert on the animals at California State University, Fresno, who was not involved with the work.
The inability to interbreed, as the new paper suggests, may have contributed to the extinction of dire wolves. Human hunting of dire wolf prey may have also played a role, as it's likely the wolves occupied North America with early Native Americans for thousands of years. They lived in North and South America, as well as China. "This result is consistent with the hypothesis that dire wolves originated in the Americas". Consequently, the researchers don't know if dire wolves lacked genetic diversity, which could have resulted the accumulation of many deleterious or disease-causing mutations. 'We also learned that they were so genetically distinct from each other that there is no evidence they could interbreed and produce offspring, ' she added.