This will be an explanation of rabbit color genetics - how the colors are inherited when you do a breeding. Learning color genetics is mostly a matter of memorizing a little information; that's what I did when I learned it. I printed off some reference material from the internet and then studied it until it started to sink in! Now I have a much better idea of what to expect in my nest boxes.
To start, we'll go back to some basic high school biology. All animals inherit half their genes from their mother and half from their father, at the moment of conception. That means that genes come in pairs, including ones for color. Each gene of the pair is called a "copy" of that gene. There are also lots of genes that influence color, not just a single pair.
Next, some genes are dominant and some are recessive.
from left to right, Top - black, black tort Bottom - blue tort, ruby-eyed white, blue, sable point
A dominant gene will be the trait that you can see or observe - all the observable genes are what make up the rabbit's phenotype - observable traits (colors, in this case). The recessive genes are ones for color that you can't see but they are there, in the rabbit's genetic make-up. When a rabbit has a gene for color that you can't see, the rabbit is said to "carry" that gene. For example, a black rabbit can carry a gene for blue. So under the right circumstances, a black rabbit can produce blue offspring. All of the dominant and recessive genes together make up the rabbit's genotype.
For a rabbit to be any particuliar color, it only needs one copy of a dominate gene to be that color. The dominant gene will hide the recessive one if it carries one - the recessive one will be there but not be observable. A rabbit needs to get two copies of a recessive gene for that color to be expressed (observable).
Rabbits' coat color, in its natural, wild form, is called agouti (ah-goot-ee). This is the color you see on wild rabbits - sort of brownish. If you could see the hair up close, each hair has different bands of color down the length of it.
Every once in a while, a gene will change or mutate. It's not even known why this happens. But it's these different changes or mutations that started different colors appearing in rabbits. The mutations restrict some of the naturally occuring colors in the agouti color (banded hair color).
To denote different colors, capital letters are used for dominant genes and lower case letters are used for recessive genes. A pure agouti rabbit's coat color is denoted AABBCCDDEE. Each of those letters shows the location of genes that control different aspects of the color of the rabbit's coat. In lionheads, agoutis are also called "chestnuts".
For a solid color rabbit (or self), the first mutation is black. A rabbit that is purebred for black has aaBBCCDDEE.
There is also at - which produces otters and martens. There is a more detailed explanation of this color variety at The Nature Trail's genetics page.
The B location changes a black rabbit to chocolate. This would be aabbCCDDEE.
The C location is trickier, as there are several recessive mutations here, which have different degrees of dominance over each other. In order of most dominant to least, they are
chd - chinchilla dark
chl - chinchilla light (sable)
ch - pointed white
c - ruby-eyed white (albino)
chd is not a mutation that I work with but there is more information at The Nature Trail's site.
chl is the sable gene; if a rabbit gets one copy, it's a Siamese sable. But if a rabbit gets two copies, it will be a seal. Seal rabbits appear almost black and are often mistaken for black. Blacks have a bluish undercolor and seals have a brownish undercolor.
ch is for pointed white or Himalayan. This rabbit is pure white with ruby eyes and color on the extremities (nose, ears, feet and tail).
The small c gene, even though recessive, has complete dominance if the rabbit gets two copies of it. A rabbit with 2 "c"'s becomes a ruby-eyed white (albino). No matter what other genes a ruby-eyed white has, the cc will hide all of them. It's been described as like throwing a white sheet over the rabbit - the other colors are there, but the white hides them.
The D location changes a black rabbit to blue (gray). aaBBCCddEE
The E location restricts the darkest color to the extremities of the rabbit (nose, ears, feet and tail), as in torts (tortoiseshell), sable points and blue points. Black torts are aaBBCCDDee.
The broken gene is En. This produces a rabbit with broken up color on a white background, ideally around the eyes, ears, across the nose, down the spine and spotting on the sides. A non-broken rabbit is enen. A broken is Enen. A rabbit with two broken genes EnEn is called a "charlie" and gets very little color spotting, not enough to be showable. Since this is a dominant mutation (most mutations are recessive), the baby only needs to get it from one parent to be a broken. If you can't see a broken pattern, then the rabbit doesn't have it and can't carry it. I have read that non-broken rabbits, that had a broken parent, will produce better marked rabbits when bred to a broken, though.
You can write out part of your rabbit's genotype by observing what you can see. Looking at the pedigree will give clues as to what else the rabbit may be carrying. And breeding the bunny will also sometimes let you know what genes it carries. The more of the rabbit's genotype you can figure out, the better you'll be able to predict what a breeding can produce. If a gene is unknown, it's
broken black with preferred "full butterfly" marking across muzzle
denoted with an underscore _. As an example, my broken sable point buck is aaB_chlcDdee. He has to be aa (he's not agouti). He's not chocolate so he is B and I don't know if he carries chocolate because neither of his parents has a chocolate gene that I know of and I'd have to test breed him to a chocolate to know if he carries it. So I put the underscore in to show I don't know. He is chl for sable and c for ruby-eyed white. His sire is cc so that's the only thing his sire could pass onto him. I've also bred my buck to a ruby-eyed white and gotten ruby-eyed white offspring, so if I didn't know the color of his sire, this would prove my buck carries "c". He isn't blue so he is D but he's had a blue baby, so he must be Dd. Sable points are always ee. So if I breed him to a doe that I know the genotype of, I'll know exactly what colors they can and can't produce.
The most important reason for knowing what colors your rabbits can have is that not all colors are accepted as showable. Non-showable colors are known as AOVs - any other variety. Sometimes, depending on the show, they are allowed to be shown.
Here are the genotypes for the 17 accepted colors in lionheads. (These colors can change as they are added to or dropped from a COD - certificate of development). This list was updated 9/7/11.
Agouti - chestnut A_B_C_D_E_
Black aaB_C_D_E_ Has passed first presentation for acceptance as a recognized breed
Pointed White aaB_ch_D_E_ (black),
aabbch_ddE_ (lilac) All colors shown in the same class.
Ruby-eyed White ____cc____ Has passed first presentation for acceptance as a recognized breed
Sable point aaB_chl_D_ee
Sable marten at_B_chl_D_D_E_
Siamese sable aaB_chl_D_E_
Smoke pearl aaB_chl_ddE_
Smoke pearl marten at_B_chl_ddE_
Tortoise aaB_C_D_ee (black) Has passed first presentation for acceptance as a recognized breed