for National Geographic News
Scientists have completed the first comprehensive comparison of the genes of domesticated dog breeds.
The analysis of 85 common typesincluding the Pekingese, Great Dane, Border collie, and dachshundfound fascinating clues about how dog breeds are related to one another, and how they may have descended from ancestral dogs in different parts of the globe. Those clues, in turn, could increase understanding about early human migration.
The findings, reported in tomorrow's edition of the research journal, Science, may also offer the first way to determine the breed of a dog based on a genetic sample. The majority of breeds tested have a unique DNA signature, despite the fact that many breeds were created only within the last few centuries.
"Since the formation of breed clubs and official breed standards only happened in the 1800s, it's really surprising that we've found such a high degree of distinction between different breeds," said geneticist Leonid Kruglyak of the Fred Hutchinson Cancer Research Center. Based in Seattle, Washington, Kruglyak is a co-author of the study.
Explosion of Breeds
The distinction found between breeds is much higher than the distinction between human populations on different continents, Kruglyak said. The variation is large enough that an individual dog's breed can be distinguished using its genetic sequence alone, he added.
"It's remarkable to find such differentiation, since the vast majority of the explosion of breeds we see today have a recent origin," commented Robert Wayne, evolutionary biologist and expert on dog genetics at the University of California, Los Angeles.
Most previous research using a different, less-sensitive type of genetic technique had not been able to detect great differences between different breeds, Wayne said.
To collect data, graduate student Heidi Parker, geneticist Elaine Ostranderboth of the Hutchinson centerand other team members contacted breed clubs across the U.S. They also scouted numerous dog shows to take cheek-swab DNA samples from five purebred dogs of each of the 85 common breeds they tested.
Over two years of focused work, with the assistance of the American Kennel Club, the team collected and analyzed DNA from 414 dogs.
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