Gerbil Genetics

 

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A lilac gerbil is groomed by a black as a spotted golden agouti stands by

 

NEWS! A Rex mutation may have appeared in Poland. More information here.

redbut.gif (305 bytes)Introduction

redbut.gif (305 bytes)Gene Tables

redbut.gif (305 bytes)What Next?

redbut.gif (305 bytes)Mutations in Other Gerbil Species

Introduction

This page is intended to provide raw genetic information. please follow the following two links if you need help in applying it.

If you are a complete beginner than first read this excellent guide to Rodent Genetics?

If you need more advice on how to apply the information on this page to your own gerbil breeding then have a look at The Applied Gerbil Coat Colour Genetics Page.

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 usually 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.

Pictures of many of the colours produced by these genes can be seen at The Gerbil Colour Palette Page.

The scientific literature that this information is based on is available. Additional information on the E and C loci has been worked out by and the Gerbil Genetics Group (GGG). The GGG can be contacted through

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 apear 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. There is a much fuller treatment of all the colours at The Gerbil Colour Palette.

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 named 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. There are pictures showing the range 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

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A photo taken in 1968 of the first Sp gerbils sent to Eric Jukes and Tony Jones (England) by Frank Lane (Canada)

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What Next?

Because the genetics of coat colour in other rodents and lagomorphs is so well studied it is possible to speculate about other genes that have not appeared in gerbils but will probably do so. These include several mutations that are sometimes reported but whose existence in gerbils needs to be properly established. This is not a complete list, there are probably hundreds of possibilities, but this list includes the most likely mutations to appear in the near future.

Ay Dominant Yellow - Increases the amount of yellow at the expense of black. Similar to e.
at Black and Tan - Black all over except for a yellowish belly. Modified "black" colours also would become available, IE, Lilac and Tan, Nutmeg and Tan etc.
b Brown - Transforms black pigment to a brown form. This would allow a Chocolate gerbil to be bred.
c Albino - Totally lacking in pigment.
cch Chinchilla - extreme dilution of yellow, but little dilution of black. Similar to g. This, when combined with at could allow for a white bellied black. Chinchilla Medium (cchm) is similar but has more diluting effect on black and acromelanistic (IE affects the body more than the extremities)
Es or Ed Steel or Dominant Black - Extension of black at the expense of yellow. The opposite of e.

As well as new colour mutations there are some mutations of hair structure that may arise. These are:

Sa Satin - This changes the cellular structure of the hair and alters the way light is reflected giving a satin like sheen
lh Long-hair - This causes hair to grow longer before it naturally drops out and is replaced
re Rex - There are many forms of Rex in other rodents. This takes the form of a sparse coat where the hairs are either curly or waved. Hairlessness, probably an extreme form of rex appeared in laboratory populations of gerbils but is now extinct. However, a rex mutation in gerbils may have recently appeared in gerbils in Poland. There is more information here.

 

Mutations in other species.

All the species of gerbil kept in captivity are a shade of agouti normal in wild rodents. However, two species, The Fat-Tailed Gerbil and The Shaw's Jird have demonstrated mutations which are displayed on their own pages. White spotting similar to that in Shaw's Jirds may have appeared in Sundervall's Jirds and in Bushy-tailed Jirds.

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Last updated 14 September 2009