Endurance.Net Ridecamp Archives

Actually it's not quite that way.  There are two colors in horses, chestnut and black.  Any other colors are different genes, called dilution genes or graying genes, etc.  The bay horse is not heterozygous necessarily; it just has dilution genes that make it bay instead of black.  There are many genes that control coat color, and some are simple, such as cremello x chestnut = palomino, chestunt x chestnut = chestnut.

Hope this helps some.  It is really quite interesting, and not so very hard to understand, just lots of "what ifs" and unknowns involved.

Louise (Biology teacher :))

Melissa Alexander <mcalex@xxxxxxxxxx> wrote:

> Barbara, say there's one gene that controls coat color -- simple
> inheritance, I believe that's called. (In practice, I don't *think* horses
> have just one gene involved in color inheritance, but the definitions of
> homozygous and heterozygous hold up.) 
>
> In simple inheritance, an individual horse inherits one part of that gene
> from his father and one part from his mother. If the horse inherited the
> same color gene from both parents, that horse would be homozygous for the
> color. If each parent contributed a different color gene, that horse would
> be heterozygous for whichever color was dominant.
>
> Each individual horse, then has two parts to this color gene. He can pass on
> only one to a particular offspring. Which one he passes is determined by a
> genetic roll of the dice.
>
> Say you have a homozygous black stallion, written BB -- a dominant
>  black
> gene was contributed by each of his parents -- and you have a heterozygous
> black horse, who also has the recessive bay gene, written Bb. If BB mates
> with Bb, statistically you'd get offspring who were BB, Bb, BB, and Bb. All
> of them would be black, but 1/2 would be homozygous and half would have been
> heterozygous.
>
> If you had two heterozygous horses, both black with a recessive bay gene (Bb
> and Bb), then the offspring would be (statistically) BB, Bb, Bb, bb. Three
> blacks, one bay. Two of the blacks carrying recessive bay. One black
> homozygous, and the bay homozygous.
>
> In practice, I don't think it's this simple. There are a lot of colors and
> combinations. I don't, personally, know if it's simple inheritance or if
> there's more than one gene involved, nor do I know what colors are dominant
> or recessive. This is purely an academic explanation of homozygous and
> heterozygous!
>
> Melissa
>  
>
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>
> Ridecamp is a service of Endurance Net, http://www.endurance.net.
> Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp
> Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp
>
> Ride Long and Ride Safe!!
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

Louise Burton
Firedance Farms Endurance Arabians
http://pages.prodigy.net/firedancefarms