Scientists have extracted and sequenced mitochondrial DNA from a partial femur of an ancient dog that lived in Alaska 10,150 years ago. Their results, published in the Proceedings of the Royal Society B, demonstrate that the animal belonged to a lineage of dogs that diverged from Siberian dogs around 16,700 years ago and may be a close relative of the earliest domesticated dogs that accompanied humans during their migrations to the New World.
‘Pre-contact’ American dogs arrived alongside people over 10,000 years ago and dispersed throughout North and South America. Illustration by John James Audubon and John Bachman (1845-1848).
The 10,150-year-old partial femur of an early dog was excavated from Lawyer’s Cave on the Alaskan mainland east of Wrangell Island in the Alexander Archipelago of southeast Alaska.
Known as PP-00128, the specimen represents the oldest bone remains found in that cave, and is the oldest genetically confirmed dog discovered in the New World.
Dr. Charlotte Lindqvist, an evolutionary biologist at the University at Buffalo, and colleagues extracted and sequenced mitochondrial genome from PP-00128 and compared it to those of modern dog breeds, historical Arctic dogs and American precontact dogs from before European arrival.
Their analysis showed that the Southeast Alaskan dog shared a common ancestor about 16,000 years ago with American canines that lived before the arrival of European colonizers.
“We now have genetic evidence from an ancient dog found along the Alaskan coast,” Dr. Lindqvist said.
“Because dogs are a proxy for human occupation, our data help provide not only a timing but also a location for the entry of dogs and people into the Americas.”
“Our study supports the theory that this migration occurred just as coastal glaciers retreated during the last Ice Age.”
“There have been multiple waves of dogs migrating into the Americas, but one question has been, when did the first dogs arrive?”
“And did they follow an interior ice-free corridor between the massive ice sheets that covered the North American continent, or was their first migration along the coast?”
da Silva Coelho et al. present a complete mitochondrial genome of a dog from southeast Alaska, dated to 10,150 before present. Image credit: Bob Wilder / University at Buffalo.
“The fossil record of ancient dogs in the Americas is incomplete, so any new remains that are found provide important clues,” said Flavio Augusto da Silva Coelho, a Ph.D. student at the University at Buffalo.
“Before our study, the earliest ancient American dog bones that had their DNA sequenced were found in the U.S. Midwest.”
Carbon isotope analysis of the PP-00128 bone indicates that the dog likely had a marine diet, which may have consisted of foods such as fish and scraps from seals and whales.
“Canines did not arrive all at once. For example, some Arctic dogs arrived later from East Asia with the Thule culture, while Siberian huskies were imported to Alaska during the Gold Rush. Other dogs were brought to the Americas by European colonizers,” Dr. Lindqvist said.
“Our early dog from Southeast Alaska supports the hypothesis that the first dog and human migration occurred through the Northwest Pacific coastal route instead of the central continental corridor, which is thought to have become viable only about 13,000 years ago,” Coelho said.
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Flavio Augusto da Silva Coelho et al. 2021. An early dog from southeast Alaska supports a coastal route for the first dog migration into the Americas. Proc. R. Soc. B 288 (1945): 20203103; doi: 10.1098/rspb.2020.3103
Source link: https://www.sci.news/paleontology/mitochondrial-genome-early-dog-alaska-09387.html
