brookcove
Posted : 7/4/2007 9:13:58 AM
I hesitate to weigh in on this one because I
do have strong feelings on where breeding for something like color has led us and our purebreds. I don't think it's really done us any favors.
On one side of the equation, the vast majority of the explanations for color preferences in breeds are just-so stories, period - reverse engineered to enforce aesthetic judgments made in the breed's inception. Or to enforce purebred status as illustrated by the founder effect in the breed (Jack Russells are no more than 51% white because most of the original terriers were).
Livestock guardians and herding dogs can be literally any color. It really doesn't matter. Most LGDs end up being some form of white because white is dominant over everything but agouti/wild. Most of the sheep/stock they originally guarded in the European mountains are colored, unimproved types. It's pretty cool when a LGD erupts from the middle of the flock after a threat, yes, but they don't lay amongst the sheep most of the time anyway. Most of the time they lay on a prominance, where colors actually blend in better.
As an historian who's made canine and livestock history a special interest, I'd be glad to uncover the truth behind any just-so story you'd like to run by me with regard to accepted breed colors. I've never found one that didn't really come down to aesthetics. And that's where I get squeamish. If you take a working breed and add requirements strictly for aesthetics, you are risking the health of the gene pool by narrowing it unnecessarily. Not to mention reducing the potential for maintanance and improvement of the working ability in the breed.
OK,
however, the reality today is that there are an awful lot of people who are breeding for no reason at all. In breeds where the working ability/aesthetic juxtaposition boat has already gone out to sea, I'd far rather see a breeder subject his or her breeding choices to the ones accepted by the peers in the breed club of his or her choice. I do realize in most breeds that means meeting conformation standards most of all.
And at this point those standards
are acting to protect the breeds in question, as mentioned above. Some of the mentioned variations are
dominant - merle is a good example. It is nearly impossible to produce merle from non-merle parents. By nearly impossible, I mean it's only possible through means of a lethal mutation. It's far more reasonable to assume there is some monkey business going on - if you hear hoofbeats, there's no need to watch out for zebras.
Ticking (spotting) is a non-lethal dominant mutation and can be passed on very subtly via the smallest spot or colored hair in the white of a white-marked dog. Ticking may be present in a self colored dog or a black and tan, and just not expressed, so it's really hard to weed out.
But other colors and modifiers mentioned are recessive. Colors are recessive to white, liver (bb) to black (Bb or BB), dilute (dd) to non-dilute (Dd or DD). ee yellow is recessive to Ee or EE (self) colored (Irish setter, yellow lab, or Golden retriever color), as are the self color modifiers sable and brindle.
Tan point is incompletely dominant, so can also be maintained in a "correct" line for many generations without emerging.
The flip side of recessives which start appearing in greater frequency in a population, is that it means that deliberate selection for these traits is occurring. Which brings us back to the wisdom of breeding specifically
for color. If one has a line in which these traits
happen to be concentrated, which has some other functional characteristic you are breeding for, I say more power to you. But it's folly to breed, say, a line of dilute colored labs just to increase the color in the breed. That's one reason Golden retrievers have such problems today compared to other breeds of retrievers.
I do live in hope that the kennel clubs will see the light and set up sensible guidelines to weed out obvious abuses, but without reducing their gene pools further. Just call me Pollyanna . . .
Edited for spelling [8|]