BASIC COLOUR GENETICS.

                                    By WARREN HILL.     

 If I had a Dollar every time I heard an Agouti carries every colour, I would be a millionaire. The fact is an Agouti may carry every colour except steel (more later).

The genes which make the colour of a rabbit can be broken up into five main groups.

                              A:               Agouti

                              B:               Black

                              C:               Full Colour

                              D:               Dense

                              E:               Extension

 A. Agouti.

 We will start with the Agouti. This can be broken into 3 parts.

               A:               Agouti Pattern

               a^t:                 Tan Pattern

                  a:               Self Pattern

These genes produce  the colour pattern of the rabbit. The order of dominance is A to a^t to a.

 The A (Agouti) produces a rabbit with a white stomach and top fur which has three bands. Colour of these bands depend on the colour of the rabbit eg. Agouti has slate blue undercolour, yellow middle colour and black tips on top. Lynx has silver undercolour, orange middle colour and lilac top colour.

The a^t (Tan) produces a rabbit with a white stomach but the top colour does not have any bands - it is one colour. There is ticking on the side of the body. Eye circles, inside of the ears, underside of the jowl, triangle at the back of the neck are either tan for Otters or white for Foxes and Marten Sables. A Tan looks like an Agouti with bands taken off.

The a (Self) is a rabbit of all one colour. It can be either Black, Blue, Brown or Lilac.

B. Black.

The next set of genes is Black. It has two parts B (Black) or b (Brown). These genes determine if the coat is black or brown ie. remove the black pigmentation and you have brown or remove the black tips from an Agouti and replace it with brown and you have a Cinnamon.

The Colour set of genes are a bit more complicated. It has 5 parts.

                              C               Full colour

                              c^chd   Chinchilla (dark chinchilla)

                              c^chl               Sable (light chinchilla)

                              c^h                    Himalayan

                              cc               Red eye white (Albino)

These genes are responsible for the amount of yellow and black pigment in the fur shaft.

C. Full Colour.

C (full colour) has yellow and black pigmentation at full strength.

 c^chd  (dark chinchilla) has all the black pigment but no yellow so a chinchilla is the same as Agouti but with all the yellow removed. Thus when the gene is used on an Otter it removes the Tan from the fur which turns it white so produces a Fox. The iris colour is marble blue.

 The c^chl (light chinchilla) has only half the amount of black pigment and no yellow. The black is turned into dark sepia on the back and lighter at the sides. The iris colour is light brown with a ruby glow in the pupil.

 The c^h (Himalayan) has no yellow pigment but does have black. The black is limited to the points on the rabbits' ears, nose, feet and tail. This is a funny gene as it is controlled by temperature. If the rabbit moults in winter the points will grow back darker than in summer. The eye colour is red.

 The c (Albino) gene removes any pigment from the fur. The eyes are pink due to the blood showing through a clear eye structure.

D. Dense.

The D (Dense) gene controls the amount of pigment in the fur shaft. D produces the full amount of pigment in the fur. This has one recessive gene d (dilution). This gene reduces the amount of pigment in the fur. You can see this under a microscope. The eye becomes blue on the d (dilute) and stays black on the D (dense). If you add this d (dilute) to an Agouti you have an opal, add it to a brown and you have lilac.

 E. Extension.

  The last of the main genes is the E (extension).

                              E^s               Steel

                              E               Normal extension

                              e^j               Brindle

                              e               non extension

The E series controls the extension of colour on the fur tips. These genes are a little different to the rest because there is a mutant gene more dominant than the wild colour(E^s).

  The E^s gene in an Agouti makes the undercolour extend half way up in to the yellow band thus making the Agouti look darker than it should. The area which is normally white turns a dark steel except the underside of the tail which is lighter than the rest of the body - this is because there is no pigment there to start with. If you add the c^chd (chinchilla) the fur will look black with silver flecks or tips.

The E (normal extension) permits the colour to be on the tips and the undercolour of the fur. It does not affect the amount of yellow in the fur shaft.

The e^j gene ( which is not present in Australia at the moment)*** behaves like a pattern gene as it makes the black and orange separate in solid patches instead of appearing in the same fur shaft. In a Harlequin, one ear is black and the other is orange and then on the side of the head where the black ear is the head is orange and then vice versa for the other side. The body has stripes of orange and black running across it.

 The last gene e (non extension) removes most of the black from the fur. If you add it to an Agouti it becomes an orange, use it on a black and it becomes a tortoiseshell, add it to a sable and it becomes a seal point. If you look closely at an orange you will see black tipping on the ears. This is because the gene is weak and cannot remove all the black. This is why the tortoiseshell has shading on the body and head.

 This article was written to show you very simply the main colour genetics so that when you look at a more complicated article it will be easier to understand.

*** Editors Note - This article was written before this gene arrived in Australia.

SELFS.

Black                                                                         aaB_C_D_E_

Blue                             Dilute Black                            aaB_C_ddE_

Chocolate(Brown)                                                       aabbC_D_E_

Lilac                            Dilute Brown                           aabbC_ddE_

AGOUTI PATTERN.

Agouti                         Black Agouti                             A_B_C_D_E_

Opal                            Blue Agouti                              A_B_C_ddE_

Cinnamon                   Brown Agouti                            A_bbC_D_E_

Lynx                           Lilac Agouti                              A_bbC_ddE_

Chinchilla                   Black Chinchilla                     A_B_c^chd_D_E_

                                  (Black Agouti with orange removed)

Squirrel                      Blue Chinchilla                      A_B_c^chd_ddE_

Orange                                                                    A_B_C_D_ee

                              (Black Agouti with black bands removed)

Fawn                           Orange Blue                          A_B_C_ddee

Steel Grey                                                                A_B_C_D_E^sE

TAN PATTERN.

Black Tan                                                               a^t_B_C_D_E_

Blue Tan                                                                 a^t_B_C_ddE_

Chocolate Tan                                                        a^t_bbC_D_E_

Lilac Tan                                                                a^t_bbC_ddE_

Black Otter                                                            a^t_B_C_D_E_

Blue Otter                                                              a^t_B_C_ddE_

Chocolate Otter                                                     a^t_bbC_D_E_

Lilac Otter                                                             a^t_bbC_ddE_

Black Fox       Otter with orange removed              a^t_B_c^chd_D_E_

Blue Fox                                                                a^t_B_c^chd_ddE_

Chocolate Fox                                                       a^t_bbc^chd_D_E_

Lilac Fox                                                              a^t_bbc^chd_ddE_

Marten Sable      Tan Pattern Siamese Sable         a^t_B_c^chl_D_E_

Smoke Pearl Marten     Blue Marten Sable            a^t_B_c^chl_ddE_

SHADED.

Siamese Sable                                                      aaB_c^chl_D_E_

Smoke Pearl              Blue Siamese Sable              aaB_c^chl_ddE_

Seal                           Dark Sable                          aaB_c^chlc^chlD_E_

Seal Point                   Orange Siamese Sable        aaB_c^chl_D_ee

Blue Point                                                            aaB_c^chl_ddee

Chocolate Point                                                   aabbc^chl_D_ee

Lilac Point                                                           aabbc^chl_ddee

Tortoiseshell              Orange Black                      aaB_C_D_ee

Blue Creme                Blue Toroiseshell                aaB_C_ddee

Gold Sussex                Chocolate Tortoiseshell      aabbC_D_ee

Creme Sussex             Lilac Tortoiseshell              aabbC_ddee

THE OTHER GENES

                                                    BY WARREN HILL

In the last year book, I wrote about colour genes.  This time it is about pattern and coat genes.  These genes are inherited separately from colour genes.

The Dutch Gene Du.

The first pattern gene is the Dutch du. These genes work different to colour genes as you need one dominant gene and one recessive gene for the pattern to be of show quality Dudu. If the genes are two recessive genes (dudu) then the pattern is too white. By this I mean the ears may have white on them, the blaze too wide and the saddle and undercut would be too far back on the body. If the genes are both dominant DuDu then the pattern has too much colour - small blaze, short stops and little or no saddle or undercut.

The English Gene En.

The next set of genes is the English en. This again has to have one dominant gene and one recessive, Enen could be of show quality. If the genes are two dominant (EnEn), unlike the Dutch then there is too much white on the body. There will be small amounts of spots on the rump rings around the eyes and markings on the nose. (called a Charlie). If both genes are recessive then the rabbit would be a solid colour (a self).

With the Dutch and English there are a lot of rabbits with the one recessive gene and one dominant gene but they are not of show quality. The pattern can be influenced by how the embryo is formed and modifying genes. With the Dutch gene the dominant Du is there in all colours and breeds but you have to add the recessive du to make the pattern show. With the English the recessive en is there in all breeds but you have to add the dominant En for it to show. This means you can put these patterns on any breed.

The combination of the du and En genes result in a white rabbit (duduEnEn) with a narrow ring of colour around the eye. This is the Blanc de Hotot.

COAT TYPES.

The long hair gene 1.

The first coat I will look at is the long hair ll. There are three different breeds with long hair - Angora, Cashmere Lop and Swiss Fox. The Cashmere Lop and Swiss Fox have similar coats - dense fur with plenty of undercoat with a heavy top coat. The Angora coat is longer denser and much finer in texture. The differences are due to modifying genes.

The Rex gene r.

The next coat type is the rex rr. This is a short plush coat. It is produced by a decreased growth of the hairs so the coat is shorter than normal. The primary guard hairs are eliminated and the secondary guard hairs are thinner than normal and only a little longer than the wool hairs. The  coat is also very dense and the whiskers are curly.

The Satin gene sa.

The third type of coat is the Satin sa. The satin effect is due to the hairs being thinner than normal with a highly reflective surface. It also makes the fur feel softer and silkier, and the colour to be brighter because the pigment granules are packed together more in the thinner hair.

The Dwarf Gene Dw.

This is the gene which is found in the Dwarf and Polish breeds. When it occurs in the DwDw combination it is lethal and the baby will die in a few days. The baby is smaller than normal, but the head looks out of proportion to the body and the hindquarters appear to be not as developed as normal. When the combination is Dwdw or dwdw the rabbit will look normal. 

The Vienna gene V.

When the rabbit is carrying the two recessive genes vv the body colour will be white with blue eyes. If the rabbit has one dominant gene and one recessive gene (Vv) the rabbit will have Dutch pattern and normal colour (this gene is not linked to the Dutch Du gene). When it appears as two dominant VV genes the rabbit will be of normal pattern and colour. This gene is also separate from the albino cc gene.

The wide band w.

This gene is found in the New Zealand Red and Tans. This gene, when inherited in the recessive state w the orange band is twice the width. When the gene is one dominant and one recessive the New Zealand Red would look like an Agouti and the tans would be Otters.

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 Date this page was last updated: Saturday, 03 October 2009