1. The "A" gene: This gene controls the distribution of pigment in the horse's coat. There are several variations, but the one responsible for buckskin is "a", which results in a base coat of yellow or gold.
2. The "E" gene: This gene determines the presence and distribution of black pigment. The "e" allele (the recessive version) produces no black pigment, leading to a lack of black points (mane, tail, legs).
Here's how it works:
* A horse with the "aa" genotype for the "A" gene will have a base coat color of yellow or gold.
* If the horse also has the "ee" genotype for the "E" gene, it will have no black pigment, resulting in a buckskin coat. This means the mane, tail, and legs will be the same color as the body (yellow or gold).
Other factors:
* The intensity of the yellow or gold color can vary depending on other genes and environmental factors.
* Some buckskin horses may have faint, dun-like stripes on their legs and back, which are also influenced by other genes.
In summary, a horse is buckskin because it has:
* A recessive "a" allele at the "A" gene (base coat of yellow or gold)
* A recessive "e" allele at the "E" gene (no black pigment)
This combination creates the characteristic golden coat with no black points that defines a buckskin horse.