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Genetics.

This section will help you:

Understand how Genetics work - The basics of how Genetics work.

The different elements or Loci of Gerbil genetics. - The basic genes that we use when talking about Gerbil genetics.

How the colours interact with eachother to produce a different colour. - Looking at how each gene effects the Gerbil.

How to work out your own Gerbils' genetics. - Using a Punett square to work out the inheritance.

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Genetics? What's this all about??

If you want to breed then it is always best to learn about Gerbil Genetics, this way you will be able to predict any colours you will get in litters, it will also aid you in making much better breeding decisions - as you will know which two gerbils to pair and then in the long run reach a colour goal you have set yourself.

At first things can seem pretty difficult, I know when I first started looking on the net at Gerbil things I wasn't at all interested in the genetics. But being the nerd I am and being quite a scientifically orientated person I eventually began looking at websties to learn these things. At the time I had no plans of breeding, certainly not for a couple of years anyway! Once I had learnt the different elements of Gerbil genetics things eventually fall into place. And now, even though I may not know a colour off by heart it is easy enough for me to work out what the code will be without looking at any genetics websites.

To make this as easy as possible I will have to start from the beginning. So I will be assuming that you do not know anything about genetics at all.

Let's start at the very beginning... A very good place to start... *cough* ahem.

A summary of Genetical Terms

Chromosome	A threadlike structure, carries genetic information.
Gamete	Mature Male or Female reproductive cell (sperm or ovum) carry half a set of chromosomes each.
Gene	A hereditary unit that occupies a specific postion on the Chromosome. It effects the phenotype and can mutate to different alleles.
Allele	A different form of a gene, there can be several different forms of the same gene.
Dominant	An allele that determins the phenotype.
Recessive	An allele that is masked by the Dominant, two must be present to have an effect on the phenotype.
DNA	Deoxyribonucleicacid.
Phenotype	visual characteristics of an organism, produced by the genotype ie fur colour, eye colour..
Genotype	Genetic code of the organism that does not show visually.
Organism	living thing, animal etc.

 

To the left is a table summarising the scientific terms that you may come across if you were to research genetics. Although I am trying to simplise this for you, you should still know the actuall scientific terms. There's only so much dumbing down that I can do.

 

 

 

 

 

 

 

 

 

 

 

Now, here is a diagram showing a Mammal cell, inside this cell is a nucleus. All mammals have these, this is how we live and reproduce. Inside this Nucleus are the chromosomes.

 

 

 

 

 

 

These chromosomes contain all our genetic information. They contain our DNA. The Chromosomes have a Centromere, this is the centre, where the two seperate parts, or Chromatids are joined together. The ends of the Chromosomes are called Telomeres. The Telomere is where our DNA is replicated.

 

 

 

 

 

 

 

When the male and female mate, their gametes meet and fuse together to produce a full set of chromosomes. This fusion then goes through the process of meiosis. Meiosis is the reproduction and splitting of cells, which eventually lead to the formation of a baby. Each Gamete carries half the number of chromosomes that makes up a full set - a full strand of DNA. As we all get half from each parent this means we will inherit some of their genes. Depending on whether or not these genes are dominant or recessive they will have an effect on what we look like, or our Phenotype.

For example:

 

On these chromosomes, from each parent there are genes. These genes will then be inherited by the offspring. As each gene has different alleles, the parents could pass on a different characteristic. These alleles are usually either Dominant or Recessive, in the below diagram they are showin by being either red or green, red for dominant and green for recessive. If you have one Chromosome with a dominant allele on it and the other with a recessive allele on it, the recessive will be masked by the dominant allele - but this recessive allele can be passed on to the offsprings own offspring...

So you could have:

 

The Phenotype of the offspring will be the same as that of the father.

You could also have the scenario where both mother and father pass on a recessive allele. This offspring will inherit both of these recessive alleles and it will have no dominant allele.

Below is a diagram showing all three possible outcomes of two gametes joinging together:

 

So let's now apply this gerbil genetics, there are 7 knwon different genes in gerbils. Each different gene has an effect on the phenotype of the offspring. These alleles determin the:

Fur colour
Eye colour

Of the 7 genes, all of them effect the coat colour in some way, some more drastically than others.

Now that you know the basics, let's do a couple of examples.

If we have one gerbil, a Grey Agouti and cross it with a black gerbil, what offspring will we expect to have?

We will assume that the Grey Agouti carries NO recessives other than the recessives it needs to make it the colour it is.

As the colour is GREY Agouti, this means that it MUST have two gg's in order to make the coat grey. So it's genotype is:

Grey agouti - AACCEEggPP

A Black gerbil has a solid belly and it MUST have aa, as 'a' is what determins whether or not it has a white belly or a SOLID belly, so its genotype is : aaCCEEGGPP.

Now, as I said before, the offspring will inherit one allele from EACH parent. So, their genotype will be: AaCCEEGgPP

Do you see where we get the genotype from??

Grey Agouti is AA and the black is aa. So take one from each parent and you will get A and a.

As the offspring is AaCCEEGgPP, it's phenotype will be: Golden Agouti.

 

Punnett Square

Here we can see how the alleles on the Loci affect whether or not the animal will be carrying the dominant or recessive of the particular gene. It is easiest if you use what we call a Punnett Square to work out the possible genetics of any offspring.

In a punnett square you need to divide the square into four boxes, on the top side you write the two loci of one parent and down the left side you write the two loci of the other parent, for example:

The letters in Purple are the first parent.

The letters in Yellow are the other parent.

	A	a
a	Aa	aa
a	Aa	aa

Therefore, the possible outcomes from these two parents are Aa, or aa.

Aa = white bellied pup, who is carrying 'a' and can pass on 'A' or 'a'.

aa = A self coloured pup, will only pass on 'a'.

Another example would be:

	A	a
A	AA	Aa
a	Aa	aa

AA = A white bellied pup, not carrying 'a' and so will only pass on 'A'

Aa = A white bellied pup, carrying 'a' and so can pass on either 'A' or 'a'

aa = A self coloured pup, will only pass on 'a'

 

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Genetics

When breeding it is best that instead of just breeding some babies, for thier welfare as well as perhaps your own piece of mind you will find yourself asking, just what exactly are the Genetics of your gerbils.

No, it doesn't change anything, whether you love your Gerbil more or not, for me I find genetics interesting and I am very much interested in finding out what my gerbils are. Plus it is fun trying to figure out what pups you could have, have or will have :)

Most would say it is ill advised to go to a pet shop and buy some Gerbils, as you have no idea of their lineage. Whether or not they are inbred or if they had or have any birth problems and you also have no idea of their Genetics so breeding will be pot luck.

Concerning Gerbil genetics there is a total of 7 different Genes. With each parent carrying two Alleles of each Gene.

So, you're probably wondering what a Gene is?? Well basically it is what causes something to be as it is. For example the Gene for human eye colour has three different alleles. These are; blue, brown and green.

Brown eye allele = Dominant

Green eye allele = Dominant

Blue eye allele = Recessive

It is generally agreed that green eye and brown eye are co-dominant, this is where either colour could be the outcome, however in general practice it is also agreed that brown will 'normally' win over green.

So if your eyes are blue then it means BOTH of your parents must have been carrying the blue eye allele. This is because the allele for blue eyes is a recessive allele. Recessive means that next to a Dominant allele the Dominant allele will always be the one that has an effect on the outcome. If one of your parents were to have brown eyes and didn't carry a blue eye allele then it is basically impossible for you to have blue eyes.

Right, back to Gerbil genetics... As I have already said, when talking in terms of Gerbil genetics we concern ourselves with 7 different Genes. These 7 Genes are what give us a basic make up of the colour and type or Phenotype of the gerbil.

The following are known to exist in gerbils:

Phenotype is what the Gerbil visually LOOKS like. For example, it has black eyes, orange fur, a white belly and black nails.

Genotype is the GENETIC CODE of the Gerbil. For example, AACCDDeeGGPP

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Let's have a closer look at each of those different genes...

A - Controls the white belly and ticking. If the Gerbil is an Agouti or self colour.

For example:

This gerbil is an agouti, it has a white belly and the top of the body has hairs with a band of orange and then black ticking on the very tips of each hair.

This gerbil is a SELF colour. It has no white belly, the belly is the same colour as that of the top of the body.

C - Controls the overall level of colour produced.

For example:

This Gerbil is CC, the coat has no changes in it at all.

This Gerbil is c(chm)c(h), therefore this Gerbil's coat is diluted, leaving colour just in the nose, tail, feet and ears. The coat is then further diluted with the c(h) to give is this 'light mushroom' colour. This coat colour is called a Siamese, it is in fact a lightened black, see it too has no white belly.

 

D -Controls the depth of colour. This is often not referred to as not many breeders in the UK have the Dilute gene in their stock.

This gene is very rare in the UK and so I have no gerbils with this gene in my stock.

 

E - Controls the balance between black and yellow pigment in the coat.

For example:

This gerbil is EE, it has no extension of yellow in its fur.

This gerbil is ee, notice the ticking on the hair is less aparant. The yellow in the fur is extended and the black ticking is only on the very tips of the hair.

This gerbil does have the yellow extension, it is ee. Notice how the gerbil appears to have no ticking in its coat, this is due to the p gene (see further down the page). The white underbelly also extends much further up the side of the body and face.

 

G - Controls the intensity of yellow and black in the coat. If the Gerbil is grey or not.

For example:

This gerbil is GG, it has yellow in its fur, the grey gene is not present.

This gerbil is gg, it has the grey gene and its coat is therefore greyed. Black is diluted to grey and all yellow in the coat is gone.

This gerbil too is gg, but it is a SELF gerbil. It has no white belly.

 

P - Controls eye colour and whether the coat is lightened. If the Gerbil has black or pink eyes.

For example:

This gerbil has black eyes, therfore it must have P.

This gerbil has red eyes and so therefore must have pp. The p gene also lightens the coat, the ticking on the hair is not as long. So you end up with a much more orange looking gerbil. It is an agouti gerbil as it has a WHITE BELLY.

 

Sp - This controls white spotting and by default is not referred to unless a gerbil is spotted.

For example:

This gerbil does not have any spotting at all.

This gerbil does have some spotting, this particular pattern is referred to as being 'Pied'. He is SELF coloured, and has white feet, as well as a full headblaze, collar around the neck and a spot on the tip of the tail.

This gerbil is also spotted, due to its coat colour it can be difficult to see, but you can see a spot on its forehead and there is another spot on the nape of its neck. This gerbil is a WHITE BELLIED, so the feet spots are not noticable.

This gerbil too is spotted, with just a small splash on his forehead and again on the neck, it has also given him white feet.

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