European Dog Breeds Almost Entirely Wiped out Native American Dogs

Modesto Morganelli
Luglio 9, 2018

However, later on, these ancient dogs vanished nearly after the European settlers arrived and left little or no trace of modern American dog breeds.

The near-absence of pre-contact dog DNA in today's pooches shows that breeds often touted as the oldest in the Americas, such as chihuahuas, are actually Eurasian in origin, Perri said.

"It's quite incredible to think that possibly the only survivor of a lost dog lineage is a tumour that can spread between dogs as an infection", co-lead author Maire Ní Leathlobhair, a researcher from the Department of Veterinary Medicine at the University of Cambridge, said in a statement.

"By looking at genomic data along with mitochondrial data, we were able to confirm that dogs came to the Americas with humans, and that almost all of that diversity was lost - most likely as a result of European colonization", said Kelsey Witt, who led the mitochondrial DNA genome work as a graduate student in the laboratory of University of IL anthropology professor Ripan Malhi, who also is an author of the study. The dogs dispersed to every part of the Americas, migrating with their human counterparts. These remains were sourced in the Americas, revealing that a rapid decline in the indigenous dog population took place following the arrival of settlers. These samples were from 9,000 years ago. The migration of dogs, according to the researchers occurred via the Bering bridge, which is located between Alaska and Siberia - his disappearance happened around 11 thousand years ago.

But then, sometime after the 15th century, these ancient dogs disappeared.

DNA analysis allowed the scientists to identify pre-contact dogs' closest relatives: a group of dogs native to Zhokhov Island, a frigid Arctic site situated about 300 miles north of the Russian mainland.

By far, the introduction of European dogs had the biggest impact.

For the study, the researchers gathered genetic information from dog remains belonging from the Americas and discovered that the ancient dogs arrived to the continent along with people who settled across North, South and Central America. But by looking at genes from more than 71 archaeological dog remains in North America and Siberia and comparing them with modern dog genes, the team was able to trace their elusive steps.

"Few modern dogs have any trace of these ancient lineages", said Witt, now a postdoctoral researcher at the University of California, Merced. Due to their isolation, the immune systems of pre-contact dogs may have been unprepared for the arrival of new pathogens. It could also be that European dogs were just favoured for whatever reason. These ancient dogs thrived for thousands of years, but were all but wiped out after contact with Europeans.

Canine transmissible venereal tumours (CTVT) are a rare form of cancer that can be transmitted between hosts, not unlike the deadly devil facial tumour disease (DFTD) that threatens populations of Tasmanian devils.

But it was the European wave of immigrants that spelled doom for American dogs, the study found. Perri said historical accounts suggest various possibilities for the demise.

Elaine Ostrander, chief of the cancer genetics and comparative genomics branch at the National Human Genome Research Institute, tells Wei-Haas, "It's the world's oldest continuously propagated cell line, which is really, really remarkable".

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