Geneticists link phenotype of Balto, famed sled dog, to modern breeds

(Press-News.org) ITHACA, N.Y. – A Cornell University-led project has added a new chapter to the story of Balto – the most famous sled dog in history – by using ancient DNA extraction and analysis to reconstruct his phenotype and identify his genetic connections to modern dog breeds.

The research reveals Balto’s lineage was genetically healthier and less inbred than modern breeds, with characteristics adapted to the extreme environment of 1920s Alaska.

The team’s paper, “Comparative Genomics of Balto, a Famous Historic Dog, Captures Lost Diversity of 1920s Sled Dogs,” published April 27 in Science.

Heather Huson, associate professor of animal science and the paper’s co-lead author, has a personal connection to dog sledding, having raced competitively for almost 25 years throughout North America. Now she studies how genetics shapes the traits – from physiology and speed to behavior and diet – that produce the ideal working canine, including detection and seeing-eye dogs.

“I was enthralled growing up with sled dogs,” Huson said. “They’re amazing athletes, they’re fast, but they have a lot of endurance. Mentally, they have to be tough. What are the genes that make them an awesome sled dog? Why can they do these amazing things that your average dog can’t do?”

While Balto was clearly a sled dog, his owner, Leonhard Seppala, was one of the founding breeders of the Siberian husky, raising the potential for some interesting overlap.

Huson teamed up with a group of researchers who were able to extract Balto’s ancient DNA – a difficult task, given how degraded and unstable the genetic material becomes over time – and they conducted the DNA sequencing and analysis. The team then compared the results of this “sample size of one” with data, provided by the Zoonomia Project, of 240 mammal species and 682 genomes from dogs and wolves of the 21st century.

The researchers found that Balto clusters most closely with Alaskan sled dogs, with a high genetic diversity and a lower burden of potentially damaging genetic variants. He also had substantial ancestral similarity to Siberian huskies, Alaskan malamutes, Greenland sled dogs and outbred dogs from Asia.

“Siberians were kind of being created at the same time as the modern Alaskan sled dogs. This shows Balto is at the crux of that. He is showing that early foundation that’s actually similar between sled dogs and Siberians,” Huson said.

There is something to be learned from any dog – even unfamous ones – whose genetic diversity has changed over time, Huson said.

“It’s kind of funny, because for evolutionary geneticists, what I’m looking at is a drop in the bucket, the 1930s versus the 2000s, while they are looking at thousands to millions of years,” she said. “Yet, the domestication of most modern breeds has been in the last couple hundred years, so there’s been a huge selection intensity on dogs in that time.”

For additional information, see this Cornell Chronicle story.

Cornell University has dedicated television and audio studios available for media interviews.

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