Gerbil coat colours

Sat Jan 02, 2021 9:52 am

Part 1: Some basic facts:

Gerbils have 6 known colour genes and one gene that affects the white spotting. They are commonly written as A, C, D, E, P, Uw and Sp (for the spots). Each of the letters denotes a locus (or location) - which describes where you can find a particular gene. Don't worry about what each one means for now, we'll get to that later.

Every gerbil (every animal in fact) has two copies of its chromosomes (one from his Father and one from his mother). So when we write down a gerbils genetic combination, it looks something like AA CC DD EE PP UwUw SpSp.

Now, sometimes genes mutate to create an alternative variation that sits in the same place as the normal gene, but acts differently. They can affect all sorts of things, from size, to looks, to personality, to health. Here, we are only looking at the ones that affect the colouring. When we need to write down that a gerbil has a mutant form of one of their genes, then there is special terminology for it - for example, the mutant of the A gene is written as a. There may be more than one variation of each gene eg. C has the normal C variation and two others: c(h) and c(chm).

Often, one variation of a gene is dominant over all the others. So a gerbil that carries both A and a looks identical to one that carries two copies of A. As a rule, we write dominant genes with a capital letter and put them first - you wouldn't describe a gerbil as being aA for example. Because of dominance, some colours need two copies of a certain gene and others just need one copy. If a colour needs just one copy of a gene and it doesn't matter what variation the other colour is, then we can leave the second space blank. For example, because a gerbil with AA looks the same as one with Aa, we cannot tell which he is just by looking, so we write A-.

Don't worry if you don't understand all of that, but I hope you get the general gist! I'll start looking at actual colours next time.

Part 2: Spots!

Something to remember is that if your gerbil's back is, say, brown (we call that agouti in gerbils) and white, then, genetically speaking he is a brown (agouti) gerbil with white spots - not a white gerbil with brown spots. This is true of all colours, not just agouti.

There are two types of gene for the Sp locus, the dominant Sp gene that creates spot and the recessive * that is found in the wild and hasn't got a name yet.A gerbil with white spotting carries one copy of the dominant Sp gene. Compare these two:

The first is Sp* and the second is **. We know that gerbil 1 is not SpSp because that is a lethal genetic combination and gerbils cannot be born with it (they die in the womb).

There is one other effect of the Sp gene, that is that it tends to lighten the coat a little bit.

That's all there is to it for spots! If your gerbil has white on his back he is Sp* and if not, he is **. (Remember that a white belly doesn't count as spots - it has to be on his back). Of course, if you've got a white gerbil, you won't be able to tell if he's spotted or not just by looking.

Part 3: Coat Colours - Golden Agouti and Black

In the wild, gerbils are non-spotted Golden Agoutis. A golden agouti gerbil is what you get if all the dominant genes are expressed. So, they are all:
A- C- D- E- P- Uw-
This is a spotted golden agouti so you can get the idea of the colouring:

They look to be brown with white bellies but if you look closely at the fur, you can see that it is not all one colour:

There are black stripes at certain intervals along each strand of hair. This is called tickling and is because of the A gene.

The A (stands for 'Agouti') gene does two things in gerbils. It gives them a white belly and it restricts the expression of black in their fur, which is why you see the black stripes. If we take it away, the gerbil's belly will be the same colour as the rest of him and the fur will be entirely black so you end up with (you guessed it) a black gerbil!
aa C- D- E- P- Uw-

Part 4: Coat Colours - ee: DEH and Nutmeg

Lets go back to our agouti gerbil, and then take away some more genes, one by one to see what they do.

The E (stands for 'extension of black') gene controls how much black is seen in the coat. E- is normal extension of black, ee is non-extension of black. So, an
A- C- D- ee P- Uw-
gerbil would much have shorter black stripes in their fur, and longer yellow ones to make up for it. This gives us a dark eyed honey (DEH), which is just like an agouti, but with much less black tickling, giving them a lighter look (notice they still have a white tummy - only the aa genetic combination will remove that)!

So, what if we had a gerbil who was
aa C- D- ee P- Uw-?
What do you think she would look like? She will not have a white belly (aa) she will have black fur (aa) but she will also have extra yellow in her fur because of the ee. Have a guess and see if you're right: maddenspace.co.uk/pictures/other/buttercup2.jpg

Don't worry if you didn't get it, but do try to understand why this gerbil looks like she does. We call this colour nutmeg and the extended black from the aa and reduced black from the ee have cancelled each other out (almost, I think there's a little more black than an agouti would have).

Part 5: Coat Colours - pp: Argente Golden, lilac, REH and saffron

The P (stands for 'pink' eyed) gene does 3 things: it turns the eyes pink, it removes the black from the coat, and it makes the yellow in the fur slightly lighter.

So, a gerbil with
A- C- D- E- pp Uw-
will be an argente golden:

Let's have a go at guessing what gerbils with different combinations of aa, ee look like with pp in the mix too. I've written the genetic code, have a think about what each recessive gene means and and therefore what the gerbil might look like. I've written a hint in yellow (top line) and the colour name on the second line - if you highlight it, it'll be easier to read.

So what does
aa C- D- E- pp Uw- look like?
No white belly (aa), no yellow stripe in the fur (aa), red eyes (pp) and no black (pp)!?
You get a lilac:
www.google.com/search?tbm=isch&hl=en&source=hp&biw=1280&bih=685&q=lilac+gerbil&gbv=2&oq=lilac+gerbil&aq=f&aqi=g1&aql=undefined&gs_sm=e&gs_upl=1010l3513l0l12l11l0l3l3l0l239l1398l1.4.3l8

A- C- D- ee pp Uw-?
Extra yellow (ee) that's lighter than normal (pp), red eyes(pp) and no black tickling (pp)
- that's a red eyed honey.
www.google.com/search?hl=en&biw=1280&bih=685&gbv=2&tbm=isch&sa=1&q=red+eyed+honey+gerbil&oq=red+eyed+honey+gerbil&aq=f&aqi=&aql=undefined&gs_sm=e&gs_upl=4398l7435l0l16l15l2l0l0l2l215l2008l1.11.1l13

and what about
aa C- D- ee pp Uw-?
No white belly (aa) no yellow stripe (aa) put the yellow back in (ee) (cancel each other out) lighten the yellow a bit (pp) red eyes (pp) no black(pp)
we call this a saffron:
www.google.com/search?hl=en&gbv=2&tbm=isch&sa=X&ei=dpkHTqWYL8SnhAeK1sXaDQ&ved=0CDkQvwUoAQ&q=saffron+gerbil&spell=1&biw=1280&bih=685

Part 5: Coat Colours - uw(d)uw(d): Grey gerbils

The Uw (stands for 'under-white') it has 2 known mutations uw and uw(d). The uw(d) mutation will remove the yellow stripe in a gerbil's fur by turning it off-white and dilute the black to grey. It also dilutes the eye colour very slightly so if you shine a light in their eye then you will see a slight red glow - this isn't something that will jump out at you though. It doesn't affect the tickling or anything so usually the resulting coat pattern is just like a black and white photo of its Uw- counterpart; but very slightly lighter.

So, an easy start:
A- C- D- E- P- uw(d)uw(d)
A- C- D- E- P- Uw- is an agouti, so this is a grey-scale agouti or, as we call it: a grey agouti

next,
aa C- D- E- P- uw(d)uw(d)?
That's a light black gerbil, or by it's real name, slate.

A- C- D- ee P- uw(d)uw(d)?
This will be cream with a small amount of dark grey tickling on the fur, it is called a polar fox. They look just like you'd expect a grey DEH to!

See! They really are grey versions of the gerbils we've already seen! If you don't know what some of these colours look like, I highly recommend doing a google image search so you get an idea.

Try these:
aa C- D- ee P- uw(d)uw(d)?
A silver nutmeg

A- C- D- E- pp uw(d)uw(d)
This is an argente golden with the yellow turned to off white: A cream! You can still make out the white belly

A- C- D- ee pp uw(d)uw(d)?
A REH (which is quite golden in colour) with the gold diluted to cream. This is called an Apricot and is not dissimilar to a cream

aa C- D- ee pp uw(d)uw(d)?
Saffron is another coat colour that is golden. Add in the uw(d)s and you get yet another creamy colour - called red eyed silver nutmeg. This is easier to distinguish from the others though, because the belly is cream not white.

aa C- D- E- pp uw(d)uw(d)?
This is interesting: A grey lilac? This actually ends up as a ruby eyed white or REW.

Credits to https://gerbilforum.proboards.com/thread/20957/gerbil-colour-genetics-beginners