Introduction
The following information can be used to work out the genetics of your gerbils, or used to work out what colours a breeding can produce.
It is focused on the colours recognised by the NGS, and follows the published scientific literature.
Gene Tables
It is important to remember that gerbils only produce two colours of pigment in their fur. Black (eumelanin) which can also appear grey or brown, and Yellow (phaeomelanin) which can also appear red. All the colours of gerbils are produced with these two pigments, or by the absence of pigment. The wild colour of the gerbil, known as Golden Agouti, is caused by the hairs of the upper surface being basically black with a yellow band, and the hairs of the belly being black but with little pigment along most of the length of the hair. If you part the hair of the back you will see the hairs are black at the base and the tip, but yellow along the shaft. On the belly you will see something similar with black bases and white or grey shafts and tips.
Throughout the following the symbols used in the Scientific Literature are used.
The following loci are known to exist in gerbils:
A – The Agouti Locus which controls the white belly and ticking.
C – The Albino Locus which controls the overall level of colour produced.
D – The Dilute Locus which controls the depth of colour.
E – The Extension Locus which controls the balance between black and yellow pigment in the coat.
G – The Grey Locus which controls the intensity of yellow and black in the coat.
P – The Pink-Eye Dilution Locus which controls eye colour and whether the coat is lightened.
Sp – The Spotting Locus. This controls white spotting and by default is not referred to unless a gerbil is spotted.
The general effect of gene at each locus in order of dominance is:
| A(+) - Agouti | |
| a | Non-Agouti - Removes the yellow stripe from the fur and removes the white belly |
| C(+) - Full Colour | |
| cchm | Chinchilla Medium - Reduces the intensity of colour on the body but leaves pigment at the nose, ears, tail etc. Has a much greater effect on yellow pigment than on black pigment. - Temperature dependant hence less effective at the extremes of the body. - NB - This gene is the same as that xometimes called Burmese and given the symbol cb |
| ch | Himalayan - Drastically reduces the intensity of colour on the body but leaves pigment at the tail. Has a much greater effect on yellow pigment than on black pigment. - Temperature dependant hence less effective at the extremes. |
| D(+) - Intense | |
| d | Dilute - Dilution of all colours due to clumping of pigment granules. |
| E(+) - Normal Extension of Black | |
| e | Non-Extension of Black (Extension of Yellow) - Reduces the amount of black in the coat in favour of yellow. |
| ef | Fading - Reduces the amount of black in the coat in favour of yellow but colour drastically fades as the animal ages. |
| G(+) - Non-Grey | |
| g | Grey - Removes nearly all yellow pigment, dilutes black to grey. |
| P(+) - Non-Pink-Eyed | |
| p | Pink-Eyed Dilution - Removes nearly all black pigment, Slightly dilutes yellow and dilutes eye colour to red. |
| Sp | Spotted - Causes white markings on the head, neck, belly and tail. The extent of markings can probably be extended by modifying genes. The basic colour will also be diluted. |
| (+) - Non-Spotted |
(+) indicates that this is the gene normally found in the wild-type. NB, Non-Spotting has not been officially allocated a symbol.
The following table sets out the likely genetics of the colours recognised by the NGS.
| COLOUR | Agouti locus | Albino locus | Dilute locus | Extension locus | Grey locus | Pink-Eye locus |
|---|---|---|---|---|---|---|
| Golden Agouti | A- | C- | D- | E- | G- | P- |
| Grey Agouti | A- | C- | D- | E- | gg | P- |
| Argente Golden | A- | CC | D- | E- | G- | pp |
| Argente Cream | A- | Cch | D- | E- | G- | pp |
| Cream (Ivory cream) | A- | C- | D- | E- | gg | pp |
| Dark Eyed Honey | A- | C- | D- | ee | G- | P- |
| Yellow Fox (Red Eyed Honey) | A- | C- | D- | ee | G- | pp |
| Nutmeg | aa | C- | D- | ee | G- | P- |
| Silver Nutmeg | aa | C- | D- | ee | gg | P- |
| Saffron (Red Fox - Argente Nutmeg) | aa | C- | D- | ee | G- | pp |
| Black | aa | C- | D- | E- | G- | P- |
| Pearl (Colourpoint Agouti) | A- | cchmc- | D- | E- | G- | P- |
| Slate | aa | C- | D- | E- | gg | P- |
| Lilac | aa | CC | D- | E- | G- | pp |
| Dove | aa | Cch | D- | E- | G- | pp |
| Ruby Eyed White (REW)* | aa | C- | D- | E- | gg | pp |
| Burmese | aa | cchmcchm | D- | E- | G-(?) | P- |
| Siamese | aa | cchmch | D- | E- | G-(?) | P- |
| Pink Eyed White (PEW)* | -- | chch | D- | E- | -- | pp |
| Dark Tailed White/Himalayan (DTW)* | -- | chch | D- | E- | -- | P- |
| Black Eyed White* | -- | cchmch | D- | ee | gg | P- |
– indicates that any gene symbol can be at that location.
* these are only four of the many ways of producing these white gerbils by combining diluting genes.
NB. These are the standard genotypes. It is possible to produce the some of these colours with different genotypes. Not all versions of a genotype given above will necessarily look alike. For example a Pearl with cchmcchm will appear darker than one with cchmch. There are also other colours which are either not standardised by the NGS and/or for which the genotypes are not yet fully understood.
Any of these colours (except for the totally white ones) can have white spots or patches. If the gerbil is so marked it has Sp gene. This gene is dominant so patched + non patched produces patched and non patched. Breeding non-spotted gerbils together will never produce white spotted gerbils. Because SpSp is fatal, breeding two spotted gerbils together will produce 25% fewer young and the rest will be 2/3rds spotted and 1/3rd non-spotted.
Although the gene causing white spotting has been designated Sp by scientists, they have not allocated a symbol to the normal wild-type gene that non-spotted gerbils have. So it is therefore technically incorrect to refer to gerbils as being Spsp or spsp. Instead, it is more proper to use the symbol +. The normal wild gerbil is therefore ++ at the spotting locus and spotted gerbils are Sp+. In practise it is easier and makes as much sense to refer to spotted animals as Sp and leave the locus blank for non-spotted gerbils.
The amount of spotting is probably controlled partly by several modifying genes. In addition, non-genetic factors almost certainly affect the amount of white spotting.
Some examples:
Here are some examples of some genotypes and the colours they will produce:
| This is agouti golden gerbil | AA CC DD EE GG PP |
| this is agouti too | Aa CC DD EE GG Pp |
| and this | Aa CC DD EE Gg Pp |
| but this is argente golden | Aa CC DD EE Gg pp |
| and this | AA CC DD EE Gg pp |
| Nutmeg | aa CC DD ee Gg Pp |
| Argente Nutmeg | aa CC DD ee GG pp |
| Dark-Eyed Honey | Aa CC DD ee GG Pp |
| Pink Eyed White | AA chch DD EE GG pp |
| but this is a Himalayan/ Dark Tailed White | AA chch DD EE GG Pp |
| Black | aa CC DD Ee GG PP |
| but this is a Slate | aa CC DD EE gg PP |