Rabbit Coat Colour Genetics

Genetics are what make a rabbit, or any living organism, look the way it does. It makes a rabbit be a certain size, be a certain colour, have a certain type of coat or ears, and more. This introduction, however, is just for the genetics concerning the coat colours of rabbits.
Chromosomes and Genes

Chromosomes are strands of DNA that act as a map. They map out exactly how the rabbit will look. In each cell, inot including the sex cells and red blood cells, a rabbit has 22 chromosomes. Each one of these pairs controls a different thing about the rabbit. For example, one might control the rabbits gender, some control colour, others control fur. Each chromosome pair has two genes in it. These genes may be the same, or they might be different, but there are always two (unless there is a genetic mutation, but we will not discuss that here). For example, a rabbit might have two genes for blue eyes. Conversely, a rabbit might have one gene for red eyes, and one gene for brown eyes.

If a rabbit has two of the same type of genes in a certain chromosome pair, it is referred to as being homozygous for that particular gene. If it has two different genes in a certain chromosome pair, it is referred to as being heterozygous.

If a rabbit is heterozygous, one of the genes is usually stronger than the other. That means that the stronger gene will be the one to cause the effect n the rabbit, and the weaker one will just hide, though it can still be passed on to the rabbit's offspring. Stonger genes are referred to as being dominant, and weaker genes are called recessive. For example, if a rabbit had one gene for red eyes and one gene for brown eyes, the rabbit would have brown eyes because the gene for brown eyes is dominant to the gene for red eyes. For a rabbit to have red eyes, it would have to be homozygous for red eyes, since the gene for red eyes is the most recessive.

Sometimes certain genes are not really stronger or weaker than another. These genes are referred to as being incompletely dominant to each other. This means if two different genes that were incompletely dominant to each other were in the same rabbit, the rabbit would have traits from both genes. In flowers, and example of an incompletely dominant gene can be found when you breed a white flower and a red flower and you get a pink flower.

Colour Genes

Each variety of rabbits requires many genes in order to look the way they look. Certain genes are related, and they are all found on the same are of the DNA strand. These groups of genes are called loci, or locus if it is just one.

You may have seen some genetics stuff written with a bunch of ABC's and other letters. Well, those are how various loci and genes are written. Genes have their own alphabet. When the "letters" of the genetics alphabet are all put together, it is referred to as the rabbit's genotype. This is basically a list of all the colour genes that rabbit has, or at least the ones that are important to understanding that particular variety.

A LOCUS

The first "letter" in the genetics alphabet is "A." This determines the basic pattern of the rabbit. The genes are as follows:

A: Agouti Pattern - These rabbits have tan, white, or fawn markings on the belly, underside of the tail, inside of the feet and legs, inside the ears and nostrils, around the eyes, and in the shape of a triangle at the nape of the neck. On the body, the fur has rings of different colours when you blow into the coat.

a(t): Tan Pattern - Like agouti pattern, these rabbits have tan, white, or fawn markings on the belly, underside of the tail, inside of the feet and legs, inside the ears and nostrils, around the eyes, and in the shape of a triangle at the nape of the neck. However, the body does not have the different colour rings when you blow into the coat.

a: Self Pattern - Each hair is a solid colour, and there are no tan, white, or fawn markings.

B LOCUS

"B" is the next "letter". This "letter" tells the rabbit how intense the colour of the fur is. The genes are as follows:

B: Black - The rabbit is black based, meaning the base colour is black or blue.

b: Brown - The rabbit is brown based, meaning the base colour is chocolate or lilac.

C LOCUS

"C" is the next "letter". This "letter" tells the rabbit whether or not to have red colouring, as well as how deep and dark the base colouring is. The genes are as follows:

C: Full Colour - The red colouration of the fur is full expressed, and the base colouring is also fully expressed.

c(chd): Chinchilla Dark - All red colouration is removed from the coat, but the base colouring is still fully expressed.

c(chl): Chinchilla Light - All red colouration is removed from the coat, and the base colouring is lightened, causing darker shading around the head, ears, tail, feet, and legs.

c(h): Californian - All red colouration is removed, and the base colouration is restricted to the nose, ears, feet, legs, and tail. The eyes are red.

c: Albino - All colour is restricted, leaving a pure white rabbit with red eyes.

D LOCUS

Next in the genetics alphabet is "D". This "letter" determines how much pigment is in each hair shaft. The less pigment there is, the lighter the colour is. The genes are as follows:

D: Dense - Full amount of pigment

d: Dilute - The pigment is less, causing the colour to look diluted.

E LOCUS

The "letter" "E" controls the banding, or colour rings (remember in agoutis where you can see the rings when you blow into the coat?) of a rabbit. The genes are as follows:

E(s): Steel - The undercolour is extended and "takes over" the colour, leaving a mostly solid coloured rabbit with some gold or silver tipped hairs.

E: Full-Extension - The rabbit has normal colour, and the bands are not disturbed.

e(j): Japanese - This takes the bands and actually seperates the band colour into different hair shafts. This is how Tricolourr and Harlequin are produced.

e: Non-Extension - There is no colour extension, leaving only what would be the intermediate band in a normal coloured rabbit. This is how Oranges, Frosed Pearls, and Tortoises are produced.

EN LOCUS

The "En" "letter" controls a different type of pattern. The genes are as follows:

En English Spotting - The rabbit is white with coloured spots.

en: Solid - The rabbit has no spots.

V LOCUS

"V" is the next "letter" in the genetic alphabet, and for most breeds, no more of the alphabet is needed to know the variety. This tells whether or not the rabbit is a Blue Eyed White.

V: Non-Vienna - Normal coloured rabbit.

v: Vienna - Blue Eyed White.

W LOCUS

This "letter" is rarely included in the genotype because it is not very important in most varieties, though all varieties DO use it.

W: Non-Wideband - Normal colouring.

w: Wideband - The red colour becomes very intense, the intermediate band widens, and the red colour "takes over" all tan pattern and agouti markings so that instead of being cream or white, they are red.

SI LOCUS

This "letter" is another that is rarely included in the genotype. All non-silver rabbits do not need this included in their genotype in order to let the viewer know that the rabbit is not silver.

Si: No-Silver - Normal colouring.

si: Silver - Silver-white hairs are scattered throughout the normal colouring.

DU LOCUS

This "letter" is usually only used when refering to the breeds Dutch, Dwarf Hotot, and Hotot.

Du: Non-Dutch - Normal colouring.

du(d): Dutch Dark - Dutch markings, mostly coloured rather than white.

du(w): Dutch White - Dutch markings, mostly white rather than coloured.

Genotypes

In order to have a full knowledge of the variety of a rabbit, just by looking at the genotype, a full genotype, using all of these loci. For example, a Chestnut Agouti would be denoted as A_ B_ C_ D_ E_ enen V_ W_ Si_ Du_. The spaces just mean that a recessive gene could be there, hidden by the dominant gene. However, most people know that the shortened form of the genotype, A_ B_ C_ D_ E_ enen, also means Chesntut Agouti.