Black genetics question - Page 2

I have the pedigree now, she is descended from German and Argentinian lines. Many dogs in her pedigree are not registered here, but some that are are Gismo Domenica, Gorbo Reststrauch, Ringo, de los Cedros, Negino von der Veck. I still do not know where the black came from and what to expect with the current breeding...

I would have to guess that it all eventually finds its way back to Roland von Starkenburg, at least that is where I found him in your dog's pedigree. (An answer to, as far as how can there be blacks in the showlines.)

This may have been said already, but it's pretty simple.

1) Black is recessive -- you need two in your genotype to show (phenotype).

2) Sable is dominant -- you need only one in your genotype to show (phenotype).

3) Black dam is therefore black-black, but sable sire could be sable-sable, sable-black, sable-b/t.

4) So pups from first case would all be sable; pups from second case would be (on average, if you bred them often) half sable and half black; pups from third breeding would be (again, on average) half sable and half b/t.

In each case, the sable may express with more pigment, and the b/t may be more black.

If she was bred to a sable and all pups were black -- that's possible, if the sable dog is the second type (sable-black) above -- but not actually LIKELY.  There is another possibility in this case -- that the black bitch is actually carrying a dominant self-color black gene that she picked up from an outcross (to another breed, where solid black is usually dominant) -- perhaps many generations back. If she keeps throwing all black litters with sable sires, you should suspect this.

Hope this helps.

Hiya
I mated my solid black stud to 3 black & tan bitches (one of them a Quantum vom Arminius x Mia von der Piste Trophe daughter) and every puppy was solid black (a couple had a few white hairs on their chests) None of the bitches, that I know of, have black in there immediate ancestry.
I have read all the items on the web about 50% being b&t and 50% being black, but thats not been the case with me.
Is it the fact that no matter what bitch, no matter what the colour, when mated to my black boy will produce black puppies.
I don't have a problem with this, as I quite like them and they are not very common where I come from so makes a nice talking point when out and about with them.
I heard that the black gene is supposed to be resessive and that it was never dominant or if it was is no longer.
I am not fully au fae with 'gene' and science, but would like someone just to give comment on this. Please. Thank you

I wish I could understand all this gene stuff.. It is very interesting....  Why is everybody trying to get black dogs?  I guess I need to look at the topic heading - but I have read alot of other threads that are trying to get black puppies.....

When you are breeding,  what are each of you trying to get.   Is there a preference of color in the show ring that each is striving to obtain? 

Katjo - you are very knowledgeable - I am not planning on breeding my dog's anytime soon - maybe never - not sure - they are still very young.  But I would be interested in your opinion on what I should breed to on my girl -

She is black and red - both her parents where sable - here is her pedigree - (you have looked at it before and gave me great in-site on her before ) so I would be interested in again you looking at it - on a breeding standpoint for color.  If I wanted to get black/red - and she is a deep mahogany red - what or who would I need to breed her with to get that deep red and black puppy. 

http://www.pedigreedatabase.com/gsd/pedigree/554393.html

I have a young pup that maybe I might breed with many years down the road - I am not sure what color is going to end up - we will say black/tan -

http://www.pedigreedatabase.com/gsd/pedigree/591778.html

what color pups do you think I would get if i bred them together....

I am just wondering on this.  Of course, if I ever did breed I would look for a male with more than just color.  Temperament, drive and clear headiness would over rule the color issue for me.  But I thought it would be fun to get your opinion on the color issue....

Haughmill, that's a very unusual scenario.  It could be explained by the introduction of the dominant black gene - K locus, from another breed, as MVF has explained in the post above yours.  I would think very unlikely that three litters, even if all three dams were recessive black carriers, would produce 100% blacks.... each puppy born would have a 50:50 chance of black:B&T (disregarding all other recessives... white etc).  How many pups were there in total?

Another explanation could be that modifiers have produced a solid black phenotype in a B&T A locus genotype.  Unlikely again I think, unless maybe all three bitches were particularly dark?

The only other explanation I can think of is that there has been a mutation in your dog.  The wild type  K^y allele that allows A locus pattern to express, has mutated to dominant K.

ETA:  Just out of interest Haghmill, what colour are his parents?  There doesn't happen to be an unbroken line of blacks in his pedigree by any chance does there?

Hiya Pod
Thank you for having a good go at my query.
The boy's mother is solid black with her dam being black and tan and sire blue/sable
The boy's father is a solid blue (the one that looks black but isn't) his dam blue sable and sire solid blue.
All the rest in the pedigree are either solid black, black and tan or solid blue (not powder but midnight...apparently)
No unbroken black line in the pedigree, they are all a mixture in each generation.
There were 6 pups, then 11 pups then another 11 pups. Out of the 27 there was 4 coated. Only a few had a few white hairs on their chest and that was the litter out of the Quantum daughter.
Hope this gives more insight. Thanks again Pod
PS the pic on my Logo is the boy I am talking about

 Very interesting!  As many of us have long suspected, there may be a dominant black gene floating around in our gene pool (as it exists in so many other breeds). The likelihood that your very fine looking stud dog is carrying homozygous recessive blacks appears quite small.  As Pod points out, there may be something else going on.

First to your dog.  There was a chance that your stud could have been a solid blue as there was blue on both sides (and the blue dilute is surely recessive -- as it is in every other breed as well).  But he is only carrying one or zero blue dilute genes as he is not expressing it.

Second to his breedings.  There were 28 pups I assume (11+11+6=28).  All black!  At best, all three bitches were carrying the recessive black gene (odds against that are low, but let's say it was 100% to make a strong case).  Even in that unlikely case, the probability of 28 out of 28 (instead of the expectation of 14) black puppies in these three breedings is... believe it or not...

3.75 x 10^-9 meaning less than 4 chances in 1 billion (million million for non Americans)!

Now, a lot of black dogs are bred to black-carrying bitches -- but how many?  I'll GUESS there are AT MOST 20,000 breedings per year in the world and, say, 1,000 fit this color genetics pattern.  Of those 1000 breedings of black to black-carrier per year, or 10,000 per decade -- or even 70,000 per human lifetime -- the chance of even one stud dog having 28 straight blacks is still very low!  The odds again of any individual dog doing this in 28 straight puppies is less than 4 in one billion.

So your (gorgeous) dog does seem to suggest that a dominant black does exist in the gsd gene pool.

 If 19 or more puppies out of 28 are black one can reject the null hypothesis that we understand the genetics correctly at the 95% level.  That may be a mouthful.  What it means is that even if there were 20 black and 8 other puppies we would have to question the idea that the black gene involved is recessive.

 I like POD's idea that the correct color may not be expressing because of a mutation carried by the sire.  I am hoping Trafalgar jumps in, as he knows the population genetics better than most.  Although POD may want to elaborate.