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.

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.

Above 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 shown 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 known 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.

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Gerbil Genes and their alleles

A - Agouti or Self coloured	A = dominant allele. Animal will have a white belly and yellow in fur a = recessive allele removes white belly and yellow.
C - Level of Colour	C = Full colour c(chm) = Chinchilla Medium, reduces intensity of colour but leaves pigment at the points ears, tail, nose and feet)also known as c(b). Temperature dependant. c(h) = Himalayan, reduces intensity of colour on body but leaves pigment in the tail. Temperature dependant.
D - Depth of Colour	D = Dense d = dilute, all colours are diluted.
E - Yellow extension	E = Normal extension of black in the coat. e = Non-extension of black. More yellow in coat and no black. e(f) = Fading, reduces black in coat in favour of yellow and also colour fades with age.
G - Controls grey in the coat	G = Non-Grey. g = Removes almost all yellow in the coat and dilutes black to grey.
P - Controls the Colour of the eyes	P = Non-Pink, therefore black eyes. p = Pink eye dilution. Dilutes black, and yellow in coat and dilutes eyes to pink.
Sp - Spotting gene	Sp = Spotted animal. Causes white spots on head, neck, tail and feet. Can also dilute the basic colour of the animal. sp = Non-Spotted. Animal is a normal colour.

So, the wild, normal coat colour for Gerbils is a Golden Agouti, the basic genetic code for this is: A*C*E*G*P*, the stars symbolise the unknown allele, which has no effect on the colour of the gerbil. If we add little 'p', the gerbil will look an orangy colour with pink eyes and be known as an Argente Golden A*C*E*G*pp. This is because the pink eye dilution causes the eyes and coat to become diluted as it says in the table above.

If we start with the Golden Agouti again, but this time adding in little 'a', the gerbil will be black! aaC*E*G*P*This is because the a removes all yellow and causes the Gerbil to have a solid belly, this is called a 'self' colour. If we then combine the pink eye dilution, the outcome is a lilac gerbil aaC*E*G*pp, this is because the pink eye dilution dilutes the eye and coat colour. Producing a silver-coloured Gerbil with pink eyes.

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 its 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, its phenotype will be: Golden Agouti. This is because, although there are recessives, remember, you need two recessives of the same allele in order for the phenotype to change.

 

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 alleles from the particular Loci of one parent and down the left side you write the two alleles of the other parent, for example:

The letters in bold along the top are the first parent.

The letters in bold along the left side 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'.