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Dominant Black? Brown?

Danni October 18, 2011 October 18, 2011

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Dominant black came up today, it this still a current theory? I found this article from Sponenburg but from what I can work out if I replace his "near blacks" with brown a lot of it works without assuming a dominant black? I especially noticed this comment at the start "Foals were sometimes born a colour close to that of bay foals but ultimately turned completely or nearly black at maturity. Isn't that the classic axample of what brown does?? Horses don't have a "K" black like dogs do they? Am I just really confused?? :D http://www.biomedcentral.com/content/pdf/1297-9686-29-3-403.pdf Love to know people's thoughts on dominant black, and what the current thinking on it is! Cheers Danni

Third Peppermint Tue, 10/18/2011 - 07:38

I'm pretty sure dominant black was disproved, so I would assume they're just brown. Or maybe sooty brown?

Daylene Alford Tue, 10/18/2011 - 08:09

That paper is 14 years old, that is ancient in the world of genetics. It theorizes an additional extension allele which has never been found E[sup]D[/sup]. It was at one time thought that dominant black in dogs was also causes by an allele at extension but this has proven to not be the case.

There still could be dominant black in horses (I mean at the K locus) but it is unlikely. I agree that the horses denoted "near black" were most likely brown. I think it was just chance that the stallion studied never sired a bay foal.

This is one of the mutations that I would love have found in horses. The other one would be Dilution (D) as designated in dogs and cats. ymwhisle

rubberduckyyy Tue, 10/18/2011 - 10:05

[quote]There still could be dominant black in horses (I mean at the K locus) but it is unlikely. [/quote]

Explain?

Threnody Tue, 10/18/2011 - 10:57

Dr. Sponenburg referenced it in recent replies on the Appaloosa Project.

Personally I would want to see any currently living foals in the study gene tested for brown. I also think some of the mares used in the study who were described as bay may have been homozygous for brown and therefore look like dark bay mimics. So when they were bred to the black stallion in the study they could only produce blacks and 'near blacks'/browns and not create foals with a 'bay' appearance.

Considering brown agouti wasn't even known at the time I think it invalidates the study. That said I don't see there being proof or disproof for dominant black possibly existing in horses either way.

Daylene Alford Tue, 10/18/2011 - 11:50

rubberduckyyy,

Dominant Black in dogs is caused by a mutation at the K locus (K[sup]B[/sup]) brindle is located there as well, k[sup]br[/sup]. I mentioned the K locus because as we have seen before, mutations in the same genes seem to have similar expressions even in different species. It is unlikely dominant black will be discovered in horses as we haven't seen any populations that seem to inherit like Dominant Black, at least now that we understand more about brown. Of course There is always a possibility of an additional mutation being discovered, just unlikely.

Danni Tue, 10/18/2011 - 16:39

Thanks, yes I thought the accepting of brown would have changed things, interesting the various theories that come around!