SEATTLE, WA – For thousands of years, humans have domesticated and established relationships with dogs. At the 2004 AAAS (Triple-A-S) Annual Meeting, a panel of dog enthusiasts (who also happen to be scientists) celebrate the canine species with new research mapping current purebred breeds back to a single progenitor breed, as well as recent findings in genetic ‘trade-off’ mechanisms that take place in dog genomes. Additionally, one panelist discusses how using genetic testing in dogs is an excellent model for similar tests in humans.
Deborah Lynch of the Canine Studies Institute will unveil a genetic map at the AAAS Annual Meeting that explores the genetic history of purebred dogs. The map features ten groups of dogs based on historical relationships.
“It’s a new way of thinking about how purebred dogs how the breeds evolved; for the first time we’ve identified progenitor breeds for each type of dog.” Lynch said at the meeting of the American Association for the Advancement of Science (AAAS).
For example, Lynch’s genetic map demonstrates how influential the greyhound was for sight hounds and the sporting group, and also will show how the Mastiff influenced breeds like Rottweilers and Saint Bernards who maintain an instinct to protect.
“The map tells us more about the breeds’ abilities and their inherited traits. All the sight hounds are grouped together, so the map arranges the breeds conceptually by groups, apart from the American Kennel Club (AKC). The AKC has not evolved from a historical relationship like this study,” Lynch said.
She hopes the map will serve as a tool for future scientific investigations, and give people a better understanding of their dogs’ nature. For example, collies or Shepherds will herd things – small children, for instance – as an intentional behavior, just like terriers might dig up gardens because they are bred to go after rats and moles, researchers said.
Karl Gordon Lark of the University of Utah discusses new findings on the regions of the dog genome, called genetic loci, which control one aspect of a dog’s shape; while at the same time changing a different aspect. Termed “trade-off mechanisms,” Lark found that one locus could, for example, elongate the snout while simultaneously decreasing the thickness of the limb bones
“These are quite different aspects of the dog, yet one can find a functional reason for why this would be so,” he explained.
Lark pointed out that this type of genetic reciprocation, or trade-off mechanism, is what you might expect in a hound that pursues prey – successful hunting hounds have long snouts, but long, thin bones. Similarly, dogs that defend territories have powerful jaws and thick bones.
“You just can’t be good at both things completely. For example, Pit Bulls won’t run as fast as Greyhounds, but Greyhounds don’t want to be in a dog fight,” Lark says.
Lark also will present data on another member of the canine family – the fox. He will show that some of the same genetic trade-offs found in dogs are present in the modern fox too. Researchers believe that the fox and dog diverged 7-10 million years ago, and while they have yet to trace the genetic loci for the fox, they know that trade-offs are genetically controlled, or inheritable in the fox.
The fact that the fox and dog have similar trade-offs tells researchers that this type of genetic mechanism was present in a common ancestor that eventually gave rise to the modern canine family in which the fox is one extreme and the dog is another.
By working closely with their owners, Lark and his team also realized that it was possible to research the genetics of pet dogs, which was not only less expensive than mice, but also created an ideal model for performing genetic testing in humans. The process follows exactly the same principles and encounters the same ethical problems as with human genetics, he noted.
Just as humans are concerned about having their genetic information used against them for health insurance reasons, “breeders don’t want people to know that their dogs have diseases,” Lark explained.
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