Introduction to Chinchilla Genetics
How Genetics Work
One of the things deciding what a chinchilla will appear like (what color it gets, how big it gets, the quality of the fur, etc) is the genes.
The genes always appears in pairs. If the two genes in a pair are the same the chinchilla is said to be homozygous with respect this gene pair. If the genes in a gene pair are different the
chinchilla is heterozygous with respect to this gene pair.
Some genes “mix” their appearance – others don’t. An example of genes who mix is the color of the human skin: When a brown and a white person have children the kids will be light brown.
The eye color of humans is an example of genes that does not mix. Genetically speaking there are two eye colors for humans: brown and blue. If a brown eyed and a blue eyed person have children the kids will become either brown eyed or blue eyed – not something in between. This is because one of the genes dominates over the other.
In our example it’s the gene for brown eyes that is the dominant gene, and the gene for blue eyes
is said to be the recessive gene.
Dominant genes are normally indicated with capital letters while recessive genes are indicated with non-capital letter. So let’s call the gene for brown eyes B and the gene for blue eyes b.
Then the gene pair determining the eye color of a person can be made of the genes: BB, Bb, bB and bb.
In the first three cases the person will have brown eyes in the last case blue eyes. It is not normal to distinguish between the combinations Bb and bB – it’s the same and normally you would write the dominant gene first if one is present. So from now on we will no longer use the syntax bB.
Every parent will pass on one gene from every gene pair to their child. In the case of blue eyed people only the gene for blue eyes can be passed on, since a blue eyed person is always homozygous with respect to eye color genes. That is in theory two blue eyed people can only have blue eyed children.
However this is only in theory. There are always exeptions. This is due to the difference between genotype and phenotype. The genotype is the actual genes that are present, while the phenotype is the genes that seems to be present. In most cases this is the same but every now and then a person can e.g. seem to be blue eyed but still carry the dominant gene for brown eyes – and thereby have brown eyed children even though the partner is blue eyed as well.
Then can two people with brown eyes have blue eyed children? Yes they can and even according to the theory. Lets consider two people that are both heterozygous with respect to eye color. In order to see what eye color their children can have we will set up a so called Punnet Square. You place the genes that the parents can pass on in the first row and the first colomn. The combinations for the childrens gene pairs can then be filled in to the remaining cells by combining the genes from the parents. This is probably best illustrated by an example. Lets look at two brown eyed people and assume that they are both heterozygous, i.e. has the genepair Bb:
From the Punnet Square it can be seen that 75% of the children will become brown eyed (25% will be homozygous and 50% will be heterozygous) while 25% of the children will have blue eyes.
Predicting Chinchilla Colors via Genetics
If you want to know what colors the offspring from two chinchillas can have you can also use the Punnet Square method. As an example we will consider two beige chinchillas – both heterozygous:
It can be seen from the Punnet square that 25% of the offspring will become homozygous beige, 50% will become heterozygous beige and 25% will become standard grey.
Lets take another example where the parents are not the same – a pink white (Pwpw-Wwww) with a standard grey (pwpw-wwww). The pink white chinchilla can pass on the following gene combinations: Pw-Ww, Pw-ww, pw-Ww or pw-ww. The standard grey will always pass on pw-ww:
It can be seen that 25% of the offspring will become Pink White or Beige/White Mosaic, 25% will become heteorzygous beige, 25% will become Wilson White, Silver or Silver Mosaic and the last 25% will become standard grey.
You can also have all kinds of hybrids (mixes of the above mentioned types).
As a last example we will try a breeding of a Wilson White and a heterozygous TOV Beige.
The Wilson White has the gene pairs pwpw-Wwww-blbl and can pass on either pw-Ww-bl or pw-ww-bl to its offspring.
The Heterozygous TOV Beige has Pwpw-wwww-Blbl and can pass on Pw-ww-Bl, Pw-ww-bl, pw-ww-Bl or pw-ww-bl to the offspring.
The Punnet Square becomes:
It can be seen that there are eight different genotypes possible for the kits. In theory all will have the same possibility of occuring so we will have:
- 12.5% probability of a Pink White TOV or Beige/White Mosaic TOV.
- 12.5% probability of a Pink White or Beige/White Mosaic.
- 12.5% probability of a Wilson White TOV, Silver TOV or Silver Mosaic TOV.
- 12.5% probability of a Wilson White, Silver or Silver Mosaic.
- 12.5% probability of a Heterozygous TOV Beige.
- 12.5% probability of a Heterozygous Beige.
- 12.5% probability of a Black Velvet.
- 12.5% probability of a Standard grey.
Adding these possibilities you will fortunately have a 100% possibility of a nice little furball so you should be garantied a great pleasure breeding chinchillas 😉