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Originally Posted by pstinard  Okay, I've formed my opinion on whether Biewers are a separate breed from Yorkshire Terriers based on the information I currently have. It could change based on new research, so it isn't set in stone, but here it is:
Based on the results of breed purity analysis conducted by MARS Labs, I can only conclude that the 100 Biewers that were tested do indeed contain DNA from other breeds of dogs. And the PCA analyses conducted by MARS Labs indicate that these Biewers are fairly uniform, and cluster in their own group separate from Yorkshire Terriers. To me, that meets the definition of a separate breed, but ultimately it's the AKC and other registries who will have to make that decision.
How these other breeds got mixed in Yorkshire Terriers to create the Biewer Terrier is somewhat a mystery to me (perhaps falsified pedigree records in the distant past or "oops" matings, but I am not going to point fingers because those people are long gone and we have no real way of knowing), but the DNA evidence is there, and it is very strong. For me, the smoking gun is the piebald spotting gene (MITF gene) on chromosome 20. This isn't a simple random mutation that can spontaneously occur over and over, but appears to have originated once during the domestication of dogs, and been transferred to the breeds with piebald spotting by crossbreeding and selection. In the breeds analyzed so far, all piebald spotting genes carry a unique DNA insertion called a SINE in the upstream regulatory region of the MITF gene (the part of the DNA that controls the expression of the MITF gene--where and when the gene will be expressed during the dog's growth and development) as well as a separate length polymorphism (segment of DNA that can vary in length) in the upstream regulatory region. The chances against both changes occurring at once spontaneously in a single Yorkshire Terrier are astronomical. My conclusion is that the piebald spotting gene had to have been bred in from another breed of dog during the development of the Biewer Terrier. The way to resolve this question once and for all would be to completely sequence the upstream regulatory regions of the MITF gene in Biewers and see whether it indeed carries the SINE and the length polymorphism. If it does, then it's a done deal as far as I am concerned that the Biewer arose from breeding a Yorkshire Terrier with another breed and re-extracing the piebald color gene.
Since I am a believer in the conservation of genetic resources, my recommendation is that Biewers be bred only with other Biewers in order to preserve their unique characteristics, which go beyond color, but also include behavioral differences. If you keep crossing Biewers back to Yorkshire Terriers, you are going to lose these unique characteristics, and end up with something more like a Yorkshire Terrier, but yet will never quite be a Yorkshire Terrier.
Okay, I'm stepping down off my soapbox now. If you disagree, it's all good, but please be kind and don't shoot the messenger. Thanks! |
Well.. that is your opinion and you are of course free to have it. And, based on the knowledge you have been able to gather I can see where you could come to that conclusion.
How do you account however for the exact same gene being in the Parti Yorkshire Terrier (in the states).. actually being documented prior to Heir Biewers pup? The yorkies in the states are producing and have produced the same Piebald gene without being bred with the Biewer or any other "mixes".. they have been DNA'd to be pure Yorkshire Terrier by the AKC. Generations of yorkies have been tested by a reputable lab for DNA parentage from a very well know yorkie breeder.
Now, if this can happen in the States with full pure bred yorkies, why does it have to be a different story with the German yorkies? Do you not think that if what the MARS lab said was really in the makeup of these Biewers (they only go back three generations) We would see some throw backs to some of the these dogs??
You stated in one of your posts that you believed that breeding back to the yorkie was a recent event.. far from it. What is recent is NOT breeding back to the yorkie. It is only within the last few years that people have decided NOT to breed back to yorkies and breed Biewer to Biewer only. (One club here in the states has always stated Biewer to Biewer only) In Germany, the country of origin, they have always bred back to yorkies, many breeders still do. Within one litter you have both yorkies and Biewers and they are registered by color into what breed they are. You can also have GoldDust and many other "colors" that are considered separate BREEDS! ooh so simple! But my point is breeding back to the yorkie is NOT a new thing at all, it was ALWAYS done, it had to be, and in my opinion it still should be.
Now, back to the MARS test.. IF the test had used a cross section of Biewers to get the markers against which all of the dogs were to be measured maybe the testing would have some validity.. However,. this was not the case. The dogs used to create the marker were from one group of people, one specific group of dogs. The samples were "submitted" by someone claiming to be a vet (who was not). Tainted test, tainted results FOREVER! Unless and until they totally start over collecting the information to get a good base.. that test is meaningless. MARS themselves have stated over and over again that this test, if taken for dogs from small populations and animals or dogs not bred in the US is note accurate.. if you look in the YT archives , I'm sure you'll find the letter from the MARS people stating such.
OK.. there, My opinion and a few questions too I guess
.. always more questions than answers!
Diana
