The Dominant Black Gene - Page 1

I wanted to start this thread after reading the thread "do showlines carry recessive black gene"

Every now and then, for the past 10 years or so, I've heard tidbits about the dominant black gene that came from the USSR.  I do believe this gene does exists in the GSD breed; it's either a mutation, an old gene that lived on in dogs exported to USSR early in the breed's developement but was bred out of the lines in Germany, or someone in the USSR crossbred a GSD with another breed of dog who had the dominant black gene.  (I think the latter is the most likely)

The dominant black gene in dogs is much more common than the recessive black gene.  In breeds such as the labrador, the belgian shepherds, many sighthound breeds, etc.  the solid black color is dominant.  Correct me if I'm wrong, but my understanding is that the dominant solid black gene is dominant over the sable gene. 

I knew of a solid black GSD owned by a breeder who has poor understanding of coat color genetics.  This dog that they called a working line had a great deal of european showling, some AMshowline, some working lines and a lot of dead-end pet lines (BYB names on the dogs and lines are untraceable online (except for buying AKC pedigree papers.))   This dog was breed to quite a few black/red pure German showline females and always produced a few solid black pups in these litters.  The breeder believed all these German showline dogs miraculously carried recessive black (and how lucky they were to have such rare showlines to carry recessive blacks!) 

I don't know what other bloodlines besides the Vogerland line from Goya who have the solid black gene, I'm sure there are others though. 
To get the the real meat of my thread, I noticed that the Vogerland black dogs and the black dog that I knew, never produced bi-colors or black sables (when bred to sable.) 

If one of these dominant black dogs was bred to a black/tan saddle-back then they would produce solid black pups and black/tan saddle-back pups (provided they were heterozygous for black/tan.)  
On the other hand, the recessive black gene in GSDs will often produce bi-colors or blanket-backs when bred to black/tan saddle-backs (and strengthen the black mask on the faces.)  The bi-colors and black-sables always carry recessive black. 
So the dominant black gene seems to do nothing for increasing the overall black coverage on sable and black/tan dogs, whereas the recessive black gene will most certainly increase black coverage of sable and black/tan dogs. 

Another quirk, this dominant solid black female seems to have some faint silvering at her shoulders, like you would see on many black/tan dogs.  Has anyone else ever seen this on a solid black?  http://www.pedigreedatabase.com/german_shepherd_dog/dog.html?id=686469  
 

Yep, there certainly is a lot of evidence for the existence of dominant black in the breed, but really the only way to be sure is to prove this by DNA identification.  The dom black allele is part of the K locus.  Not a gene routinely screened in the GSD but I'm sure Healthgene would be only too willing to run the test if a candidate dog was to submit DNA.
http://www.healthgene.com/canine-dna-testing/color-testing/?tid=4&btid=66

The silvering on the dominant black (assuming she is) is typical of heterozygous expression K k^y and what's known as seal in some other breeds, so similar to homozygous expression of recessive black.  Far from doing nothing for increasing overall coverage of black on sable and B&T, it conceals them almost completely.

I do agree that heterozygous expression of rec black can darken other agouti patterns but I'd question that bicolours always carry it.  It doesn't follow in other breeds where bicolours breed true eg Dobermanns, Bernese, Manchester Terrier etc.  There are many bicolour breeds where rec black doesn't exist.

Thank you pod, that was very informative :) I've seen seal black cats and pitbulls but quite interesting to think of a seal black GSD. 

You are right about the bi-colors in other breeds, like dobe and rott, who do not have solid black. 
Perhaps the pattern gene in those breeds that make them bi-color is a separate combination of color/pattern genes than the bi-color pattern of the GSD?  Does anyone know of a bi-color GSD that does not carry solid black?  I simply have never heard of a true bi-color GSD (with black pencil toes and tar heels) that did not carry the recessive solid black gene. 

I'd like to be able to purchase one of those Vogerland dogs that seem to be dominant solid black and have it tested for the K locus to know for absolutely sure (and have proof of it)

It has been my impression that the recessive black gene helps prevent fading of saddle/mask in the GSD, is this true?
I don't believe the dominant black gene makes any improvement for black markings on a saddle-back or sable dog.  So with that in mind, the dominant black gene may not be as good of value to the GSD breed as the recessive black gene is (except for those who are breeding specifically for solid black dogs.)

Quote
"I knew of a solid black GSD owned by a breeder who has poor understanding of coat color genetics.  This dog that they called a working line had a great deal of european showling, some AMshowline, some working lines and a lot of dead-end pet lines (BYB names on the dogs and lines are untraceable online (except for buying AKC pedigree papers.))   This dog was breed to quite a few black/red pure German showline females and always produced a few solid black pups in these litters"

I knew of a black sable stud that appeared to be black, was only apparent he was a sable when he produced sable pups to non sable bitches so it is possible some of his black pups to non black carriers were also black sables.  Could it be the case with this dog?

Margaret N-J

Does anyone know of a bi-color GSD that does not carry solid black?  I simply have never heard of a true bi-color GSD (with black pencil toes and tar heels) that did not carry the recessive solid black gene.
 

Yes, I am pretty sure that I have a female who doesn't carry for black but is bicolor. I've been calling these dogs "bright" bicolors because their tan areas are larger and usually very clear tan. I bred her to a dog who is sable/black and her puppies were either sable or bicolor (no blacks). I've seen other bicolors that look like this, too--they usually have very distinct eyebrows, a throat patch, and chest markings--much like a doberman, say.

She has toemarks, but it's hard to tell from this picture:




Christine

I knew of a black sable stud that appeared to be black, was only apparent he was a sable when he produced sable pups to non sable bitches so it is possible some of his black pups to non black carriers were also black sables.  Could it be the case with this dog?
 

This could have been a dog who carried the dominant black (so appeared solid black) but also had the sable and recessive black genes on the agouti locus.

Euro, yes seal pattern has mostly been obseved in close coated breeds like the terriers and some hound breeds but I'm sure some of the faded blacks that occur in longer coated breeds like the Border Collie, Belgian Shepherd, could also be seal.  The cat though is a different kind of seal.  It's where the himalayan pattern turns black pigment brown.

It seems pretty clear that the presence of recessive black does contribute to pigment intensity in sables and possibly tanpoints (bicolours, saddles, B&Ts), but it is not the only influence.  Mask is a separate gene, and no doubt there are modifying genes that also contribute.  The actual Agouti pattern gene, and tanpoint allele that produces bicolour, saddle, B&T, blanket back etc has been DNA identified to be the same in all breeds.  

"I don't believe the dominant black gene makes any improvement for black markings on a saddle-back or sable dog."

If dominant black is present, the dog will be black.  There are exceptions to this of course, a genetically dom black dog can be white if recessive ee is present, but generally if one or two K alleles are present the dog will be black.  There is no way that it can only partially improve markings or pigment because it is fully dominant, unlike recessive black that clearly has a partial influence in the heterozygote in some cases.  A saddle or sable dog can't carry dominant black.

The father of this pup, for example, produces some nice black progeny, from typical blk/red females: http://www.pedigreedatabase.com/german_shepherd_dog/dog.html?id=696344  I always wondered how that was possible. Very interesting about dominant black gene.

BlackthornGSD,

The picture you posted looks more of a very dark black/tan, I wouldn't call her bi-color though she could be. The markings obove her eyes and on the chest plus the quantity of black on her legs and arms do not suggest she's a true bi-color. The dog in your avatar looks to me is a true bi-color and a very beautiful one.

Ibrahim 

It seems pretty clear that the presence of recessive black does contribute to pigment intensity in sables and possibly tanpoints (bicolours, saddles, B&Ts), but it is not the only influence. 
 

I don't think it's one bit clear.  There's plenty of bicolors with recessive black and poor pigment, and plenty of showline dogs with no recessive black and great pigment.  Or should I say, "multitudes".  I don't think it's clear that recessive black has ANY influence on pigment. [except in it's homozygous state, in order to CONCEAL pigment]