Join Date: Jan 2010
Location: Gloomy Indianapolis
Well I am no expert, lol but I do know some. She is a grulla, which means she is a black horse with the dun modifier. Are you sure her sire was a buckskin overo(tested) or is it possible he was a dun overo? That's the thing about genetics, even with a complete family history you can't always tell for sure without genetic testing. For her to have a grullo foal, it is likely she is homozygous for black because both a grulla and a buckskin have a base coat color of black, but nothing is for certain, she could still have managed to get a recessive red from one of the parents. As I am working this out in my mind,lol, a "zebra dun" (the ones that look like a buckskin) is actually a bay horse with dun. A bay is a black horse with the agouti modifier that changes the body color but not mane and tail or points(typically). She would have given a black gene no matter what, which is dominant over red and we know the Halffie had red. It IS possible however, that she does indeed have a red gene and it was just the luck of the draw.
If her mother has had a palomino foal, correct me if I am wrong people, but I believe that means she has to have a recessive red gene hiding behind the black and the dun modifier. If not, she would have given baby a black no matter what and black is dominant over recessive red. A palomino is a red horse with a dilute gene.
The short of it is, genetics play a HUGE part in color, and we are still learning new things about color genetics. I am like you, I find it fascinating, but it will be a long time before I understand it completely,lol. And don't EVEN get started on the LP(appy) genes, I get totally lost,lol.