Dogs may descend from two different populations of wolves
(Pixabay / Jeannette1980 https://bit.ly/3nvwe7l)
Our beloved dogs may actually have evolved from two populations of wolves: Middle Eastern and Siberian.
A team of biologists from the Francis Crick Institute (FCI) came to this conclusion after analyzing the genomes of 66 ancient wolves.
Early humans probably domesticated wolves in the east and west of Eurasia, and their descendants mixed with each other.
Another hypothesis suggests Siberian dogs that settled in the southwest of Eurasia hybridized with local wolves.
Modern theories suggest that all modern dog breeds are descended from wolves (Canis lupus). However, we don’t know yet when and where exactly they were domesticated.
The oldest remains of dogs are about 14,000 years old, and genetic analysis indicates that the separation of the evolutionary lines of dogs and wolves occurred around 40,000 years ago.
Most genetic research on the origins of dogs uses genetic data from modern and ancient dogs, as well as modern wolves.
THE STUDY
Now a team of researchers led by Anders Bergström of the FCI have suggested that this is not enough: dogs may have extinct wolf populations among their ancestors.
In order to find out this,Bergström’s team sequenced the genomes of 66 ancient wolves from Europe, Siberia, and northwestern North America.
The results were compared with data on the genomes of:
- 68 modern wolves
- 369 modern dogs
- 33 ancient dogs
They also analyzed genomes from other canine species covering a sample of about 1,000 years.
The team found that the ancient wolves are grouped not by the place where their remains were found, but by time: The younger, the more they have in common with modern wolves.
This means that over the past hundred thousand years, the wolf population has been panmictic and formed a single gene pool.
The researchers think this probably allowed them to survive, while many other large predators became extinct.
Interestingly, even before the maximum of the last glaciation, wolves from Europe, Siberia, and North America did not differ much from each other.
(32,000 year-old wolf skull sequenced as part of the study. / Love Dalén - The Francis Crick Institute)
GENES FLOWING
Today, wolf populations are much more differentiated. Most likely, due to the decline in their numbers.
All wolves that lived earlier than 23 thousand years ago (before the maximum of the last glaciation), were similar to modern Siberian wolves from a genetic point of view.
This suggests that throughout the Late Pleistocene, Siberian wolves regularly migrated to Europe.
At the same time, the study didn’t reveal signs of gene flow in the opposite direction in the Pleistocene.
However, in the genomes of wolves from Europe, the genes of their ancestors, who lived here before the start of waves of migration from Siberia, were still preserved.
In the Holocene, later than 10 thousand years ago, the flow of genes from Siberia to Europe stopped.
Instead, European wolves began to spread eastward and contributed to modern Siberian and Chinese populations.
Researchers identified an admixture of coyote (Canis latrans) genes in the genomes of ancient and modern wolves from North America.
These two species diverged from 700 thousand to a million years ago, but 100-80 thousand years ago hybridization took place. However, the admixture of coyote genes did not spread to Eurasia.
At the same time, Siberian wolves regularly migrated to Alaska and the Yukon region, but not in the opposite direction.
Bergström’s team estimates that the genome of modern North American wolves contains 10%-20% of the genes of coyotes and 80%-90% of the genes of Siberian wolves that lived after 23,000 years ago.
They didn’t identify admixtures from older North American populations.
Additional analysis made it possible to identify 24 regions in the wolf genome that were subjected to the pressure of natural selection.
The frequency of one of the variants of this gene increased from zero to one 100% about 30-40 thousand years ago.
Perhaps this is due to changes in the composition of the prey of the wolves.
Another 3 areas with signs of selection are in the genes for olfactory receptors.
In most cases, selection took place before the separation of the evolutionary lines of wolves and dogs.
(Different gene distribution across Eurasia. / A,Bergström et al - Nature, 2022)
MODERN DOGS
The authors associate the origin of dogs with wolves that lived in the northeast of Siberia 13-23 thousand years ago.
They inherited 100% of the genes of ancient dogs from Siberia, America, East Asia and Northeast Europe.
However, Siberian wolves were the main, but not the only ancestors of dogs.
Their analysis showed that some ancient Near Eastern and modern African dogs (20%-60%), and to a lesser extent European dogs (5%-25%), are related to wolves from Western Eurasia.
They probably arose from the independent domestication of wolves from the Middle East or the Caucasus, and later hybridized with dogs of Siberian origin.
According to an alternative hypothesis, Siberian dogs, after settling in the southwest of Eurasia, interbred with local wolves.
In different breeds of modern dogs, the proportion of the Siberian and Middle Eastern components differ, but in general, the Siberian prevails.
The team thinks that as dogs don’t have a link with the modern wolf populations, they might have ancestors that died out.
However, if dogs are indeed descended from independently domesticated wolves from Eurasia, then it is possible that their ancestors are still alive.
I now wonder the origin of cats.
Sources:
I saw that here and had it saved for latter. Now I don't have to go back to it. Thanks!
I think I had seen before that dogs emerged independently in two different evolutionary pathways, but it's interesting to see it again. If I remember correctly, the previous theory I heard was that something like dogs emerged in Russia, but then died off again, and thousands of years later a new type of dog emerged independently in Europe or the Middle East.
It is also interesting to learn here that the wolves were more similar before the peak of the last glaciation. I guess the ice bridge between Alaska and Russia let them spread between continents, just like the ancient human migrants. As you said, I guess population shrinkage stopped the migration from Siberia to Europe.
I had read that it was China, rather than the Middle East, but the result is fairly the same. Other aspect I found fascinating is that dogs got wild again like the Dingos.
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