NEW YORK (GenomeWeb News) – Alaskan sled dogs share a genetic profile that may reflect breeding for specific behaviors in these dogs, according to a paper appearing online today in BMC Genetics.
By genotyping almost 200 Alaskan sled dogs at microsatellite markers across the dog genome and comparing these patterns with those in about 140 purebred dog breeds, researchers from the National Human Genome Research Institute and the University of Alaska at Fairbanks have tracked down a distinct genetic signature in the Alaskan sled dog — along with clues about breeds that have contributed to sprinting ability, endurance, and other traits in these dogs.
"Instead of this breed being established on appearance, like most purebreds, they were established based on their performance and some behavioral characteristics," lead author Heather Huson, a graduate student at the University of Alaska who is working on the sled dog project at Elaine Ostrander's NHGRI lab, told GenomeWeb Daily News.
Alaskan sled dogs have been bred to not only thrive in harsh northern environments, but also to pull heavy loads across long stretches of this snowy terrain — originally for practical transport purposes and, more recently, for recreational racing.
Though they are a mash-up of several northern dog lineages — and not designated as an American Kennel club breed — Alaskan sled dogs tend to be commonly considered as a breed due to their behavioral specialization, the researchers explained. And, they say, studying these dogs offers "a rare opportunity to investigate the development of a dog breed based solely on performance, rather than appearance."
Although past studies have looked at sled dog physiology, noted Huson, who grew up racing sled dogs, researchers have known relatively little about sled dog genetics.
"The long-term goal of this study is to understand the genetic underpinnings associated with both the genetic heritage and the elite athletic performance of Alaskan sled dogs," she and her co-authors wrote.
To do this, the researchers used Sanger sequencing and ABI GeneMapper 4.0 to genotype 199 Alaskan sled dogs from eight kennels recognized for producing dogs specialized for either sprint or distance racing at 96 microsatellite markers.
The team then compared sled dog genetic patterns with published data on 132 dog breeds as well as newly generated genotype data on 44 dogs from nine more American kennel club breeds.
That analysis suggests Alaskan sled dogs appear to be genetically related to 21 domestic dog breeds, including Alaskan Malamutes, Siberian Huskies, Pointers, Samoyeds, Chow Chows, and Akitas.
Even so, the researchers found that sled dogs fell into their own genetic cluster, distinct from other dog breeds. "They established their own signature, their own pattern of these microsatellites," Huson said.
And, unexpectedly, the sled dogs seemed to cluster together even more closely than some recognized breeds, including Malamutes and Siberian Huskies.
The team argued that such findings "establish the Alaskan sled dog as a breed, distinguishable by its genetic profile, regardless of the population's diversity in appearance and its mottled history."
Within this group, they also saw further genetic stratification, identifying genetic patterns that coincided with sprint and distance racers and even, to some degree, with a dog's kennel of origin.
For instance, researchers found that sprinting sled dogs carried breed signatures from Hunting dogs, including German Short Hair Pointers and English Pointers, which have been bred into the sprint dog population over the past decade or so to increase their speed, Huson explained.
Although all sled dogs seem to share breed signatures corresponding to Alaskan Malamutes and Siberian Huskies, dogs specialized for distance racing appear to be slightly more closely related to these dogs. The team also detected breed signatures from the "Mastiff/Terrier" group in the distance dogs.
The team's subsequent experiments offered clues about everything from the level of inter-breeding between various sled dog groups to genetic patterns associated with high and low speed, endurance, and work ethic performance.
"What this does, in the big picture, is it shows the dogs that are most related to sled dogs," Huson said, "and that helps set the foundation for doing whole-genome studies of the sled dogs."
She and her co-workers are currently working on follow-up genome-wide association studies using microarrays to look for genes or parts of the genome linked to speed and endurance as well as other traits, such as mental stress tolerance.