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Originally Posted by Pinehaven  I agree with you here but I understand AKC's point too. AKC is a breed registry. They DNA tested numerous litters and living generations of this parti line and they spoke to old time breeders who saw parti show up in their own litters ... AKC feels as I do, that they are Yorkshire terriers because of their PUREBRED bloodlines and AKC understands how recessive genes work.
By allowing these colors to be registered against YTCA's wishes (obviously), it has created a mess.
But here's an example of how genes can hide for many generations. The American Morgan Horse assoc. put a rule in the books 50 years ago, called the high white/blue eye rule, it was like the parti DQ rule. It was put in place because a single line of morgans started producing pinto coloring and the Morgan standard called for black, brown, chestnut or bay horses with minimal white markings. This rule, denied horses with white above the knee or blue eyes to be registered (trying to keep the pinto genes out of the gene pool).
In the 80's blood typing became mandatory for registering foals and in the late 90's to the early 2000's, it was switched over to DNA. Then in 1996, the rule was repealed and it was felt by many, that the pinto gene had been erridacated from the gene pool but minimally white marked horses (who were actually carrying different genes for pinto coloring) began throwing louder marked foals with white over the knee and sometimes belly spots. I had my own surprise pinto foal born that year and I must have called the registry 5 times in 24 hours to see if I could register him. Luckily, he was born 3 months after the repeal of the High White rule so I named him High White Revolution aka, Rebel and he's registered with the American Morgan Horse assoc and double registered with a pinto registry, he's a minimally marked sabino with stockings above the hock, 8 inch belly spot, other various disconnect small spots and an apron blaze. This is where my interest in color genetics began. PictureTrail: Online Photo Sharing, Social Network, Image Hosting, Online Photo Albums - slide show of Rebel, 4 of the photos are when I owned him.
Today, 50 years after the High white rule began and 25 years after parental verification started through blood typing and/or DNA, here are two examples of how pinto coloring is popping up out of minimally marked parents - these two horses are the loudest marked Morgans that I'm aware of, both get their pinto markings through the splash gene. http://memcmorgans.com/Tiger/Tiger-ad.jpg pinto news
My point here is that these sneaky spotting genes, can hide in the form of "accepted" minimal white markings in animals for many generations. It happened in the Morgan breed and it happened in the Yorkshire Terrier breed as well. |
The difference in your example with horses and with Yorkshires is that Yorkshires have never allowed white markings at all, except for those present at birth which turn tan/gold as the dog matures.
I'm not fully versed on the dilutes but that is apparently what is happening with the horses. If you take 2 minimally marked horses, which, according to your post is acceptable, and bred them, you could expect there to be a foal with more white than either parent at times. I could liken that to breeding two 7 pound Yorkies (acceptable size) together. You may not only get 7 pound offspring, but actually have pups bigger than either parent. You are essentially exaggerating an acceptable trait into something not acceptable. Then if you were to breed the bigger pups, resulting offspring could go even larger.
I believe that if one were to breed 2 Yorkies together that were barely dark enough to have the acceptable steel blue, some pups would be lighter than either parent, due to exaggerating the dilution factor, and fall into the unacceptable category. Now it's not so cut and dry, with each breeding having its own particulars, but the point is to be selective enough to not exaggerate any fault in future generations.
You have probably heard, as well as I, that some breeders have in the past used red leg Yorkies to preserve the color. Coat color is apparently not some static feature that can be just duplicated generation after generation. My feeling is that, if you breed a fault to a fault, you not only re-produce that fault, but in some instances will exaggerate it. That's where selective breeding comes into play to maintain and preserve a standard.
All this discussion of how a certain color came to be in an animal is a really a moot point, however. The Yorkshire terrier has always been a blue and tan dog, AKC registration notwithstanding. Some of the old breeders may have been illiterate, but they sure knew what they were doing with the Yorkshire. Their knowledge may have come through trial and error, but they got it right in drawing up the first standard. It has been tweaked since then, but has never allowed for any white on a mature Yorkie. Your example with the horses shows to me why they were right.