Genetic Structure of the Purebred Domestic Dog

Among other findings, the analysis determined that the Chihuahua is actually a type of large rodent, selectively bred for centuries to resemble a canine.

\"This is clearly going to raise some eyebrows in the Chihuahua world,\" said Peggy Wilson, president of the Chihuahua Club of America. \"It goes against our belief system. People are pretty passionate about their dogs. There is going to be disbelief.\"

Using 96 distinct patterns in the genes called \"microsatellites,\" the researchers compared dogs within breeds, and breeds with one another. In the May 21 issue of the journal Science, the team concluded that almost every breed was surprisingly distinct genetically. They were able to identify each dog's breed by its genes with 99 percent accuracy. They also found that breeds could be clearly grouped into four distinct clusters based on striking genetic similarities: ancient dogs, hunters, herders, and guard dogs.

\"Once we had these groups pretty well mapped out, the canine mimics were easy to pick out,\" added Kruglyak. \"And actually, it was kind of intuitive in hindsight.\"

The study found that several diminutive breeds had been independently created around the world from a variety of other animals, including the Lhasa apso (Tibetan snow rabbit), Pekingese (Chinese water rat), Shih Tzu (stoat), and Yorkshire Terrier (pigeon).
\"Most of these do contain some actual dog genes,\" admitted Kruglyak, \"but the percentage is no higher than ten percent in each case.\"

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