Question about color genetics

[Kari]

Hi,

Genetics really confuse me sometimes. I'm learning, but there's A LOT I am still unsure about!

Is it possible for one homozygousty to "override" another??

For example, a mare that's homozygous for tobiano is bred to a stallion that's homozygous for black, and the result is a solid black. Does this mean the mare isn't homozygous for tobiano? Or did the stallion's black override the mare's tobiano?

Every other foal the mare has had (four) has been pinto...

Any input would be greatly appreciated!!

Kari

 

[love_casper]

The only genes that techincally "override" others would be modifyer genes like agouti (bay), grey, etc.

If you are sure the mare is homozygous, has been tested etc, then ALL her foals will be tobiano. I would bet that the foal you're talking about is actually a tobiano, just minimally. Pintos aren't always neccessarily loudly marked, it can be present in the form of leg white, like a sock, and sometimes nothing else.

A pic would help, but if the foal has any white at all I'd attribute that to tobiano. Unless it's face white, tobi doesn't cause face white.

 

[Mona]

Black is a color and tobiano is a pattern, so one cannot over ride the other. The resulting foal would be a black based tobiano pinto.

Black is a color and tobiano is a pattern, so one cannot over ride the other. The resulting foal would be a black based tobiano pinto.

I should also mention, that the tobiano pinto as I mentioned above, can be from minimal white to maximum white markings, and can also be combined with other patterns, such as overo (making tovero), appaloosa(making pintaloosa) etc.

 

[targetsmom]

I have seen in person and on the forum, tobiano pintos that are either homozygous themselves or were the product of a homozygous parent and they appear solid, usually with socks or some white. I would get the foal tested and I'll bet it tests positive for tobiano even if it appears solid. Was the mare tested or do you just assume she is homozygous for tobiano? Of course, if the mare isn't actually homozygous for tobiano, then the foal can be solid. Testing will give you the answers!

 

[Kari]

Thank you for clearing that up!

As far as I know, the mare's never been tested, and I've never seen the colt, so... *shrugs*

Kari