Writing about genes and their influence on breeding chinchillas will definately be the most difficult part of the website to write. Genes are very complex but I will try to write it as simple as possible so that I can also understand it. You can write a book on genes alone but this is not the idea. If you understand the basic principles and a few big NO-NO’s you will be allright. If you need to know more than what I will write it becomes complicated but extremely interesting. Let’s start with the basics first and see if we need to know more. So here we go.
In order to explain what happens to cause mutations in chinchillas it will be neccessary to look at a bit of basic biology. I’m no biologist and will omit a lot of stuff not relevant to chinchillas (mostly because I don’t know the other stuff but I also don’t want to complicate things). We all know that all living organisms are made up of cells. When cells divide to form growth, chromosomes are formed. These can be various forms and some contain the factors of inheritance. Chromosomes always appear in pairs and there will always be the same amount of chromosomes in each cell for a specific species. Human cells have 48 chromosones. Monkeys, rabbits and hedgehogs also have 48 chromosomes. This doesn’t mean that we are descendants of monkeys, allthough you get humans that act like monkeys (the ones who don’t look after their animals). The amount of chromosones also doesn’t make an animal smarter. Even crayfish and armadillos have more chromosomes than humans. Chinchillas have 64.
The hereditary factors which are the integral parts of chromosomes are known as genes. There are thousands of them in each chromosome. They determine the development of a new individual and will determine what the new individual will look like. Genes occur in pairs in all cells of the body with one of each pair being present in each of two corresponding chromosomes. It makes you think of dominoes and it is basically how it works (very basically). So genes are the little thingies that makes us look like we do. We must just remember that we get genes from both our parents and that makes us similar to but also different from them. When Granny says that you have mommy’s eyes she might be right. But what she can’t see is that you have daddy’s temper, so stop pinching my cheeks! The characteristics that can be seen, like the colour of the eyes is called the animal’s phenotype. What can’t be seen, like it’s ability to produce strong healthy offspring (or a bad temper), is called the genotype.
Alleles are one of two alternate pairs of genes of the same trait that occupy the same position on chromosome pairs. These alleles are responsible for alternative traits, like colour and size. We will only be discussing colour but they have a much bigger influence like size, coat quality and temperament. Alleles that differ from the existing ones can arise from mutations, giving us the new colours of chinchillas that we find nowadays. We must remember that all chinchillas originated from the standard grey form and any other colour than standard is a mutation. When the alleles on a chromosome are gene pairs that’s the same they are homozygous. When the alleles are different gene pairs they are heterozygous. Now it’s getting complicated.
When the female forms an egg for reproduction the egg will only receive one of the two genes in a pair. When the male forms sperm the sperm will also only receive one of the two genes in a pair. The genes will become a pair again when the egg and sperm unite to start growing into an embrio. The embrio will therefore have a gene from each parent. But some genes are dominant over other genes. This means it will mask or hide the characteristics or traits of the other gene. Therefore we talk about dominant genes and recessive genes. So a homozygous chinchilla will have 2 dominant or 2 recessive genes and a heterozygous chinchilla will have one dominant and one recessive gene. What it comes down to is that when the chinchilla have 2 dominant genes (homozygous) and it mates with a chinchilla that has 2 recessive genes the dominant gene will always show in the offspring. The easiest example is to mate a homozygous beige (2 dominant genes) to a standard grey (2 recessive genes). All the babies will be beige but will not be homozygous. The dominant beige gene will mask the appearance of the recessive grey gene, resulting in beige babies, although one parent is grey. This means that the grey gene is still present but does not show because of the dominant beige gene.
People have asked me how it happens that 2 beige chinchillas can produce a grey baby. This is the reason. Every heterobeige chinchilla have a beige and a grey gene. When the egg and the sperm forms it will each receive one gene. If one of them receives a beige gene (dominant) and one receives a grey gene (recessive) the baby will be heterobeige. Both genes are present but you can only see the beige gene. If both the egg and the sperm receive grey genes the baby will be grey, there is no dominant gene present to mask the appearance of the grey genes. If both the egg and the sperm receive beige genes the baby will have 2 beige genes, making it homozygous beige (2 dominant genes). A standard grey chinchilla is therefore also homozygous but because both genes are recessive (can be dominated) you get different colour babies when you mate a grey with for example a white.
If we know which colours are dominant and which are recessive it makes predicting the outcome of the babies a bit easier. For colour in chinchillas the dominant genes are Velvet (or Touch of Velvet), Beige and White. Standard is recessive to them but it does not mean that all babies will be this colour. Remember there are 2 genes involved. It just means that if the Velvet, Beige or White gene is carried over to the baby it will be dominant and the baby will be that colour. White is not always completely dominant and this gives us White Mosaic. For example, if you pair up a Standard with a pure White you will mostly get Mosaic but can also get Pure White, Silver White, or when paired with Beige, Pink White (This is called LUCK). Velvet, Beige, White and Standard are dominant over Charcoal, Violet, Sapphire and Recessive Beige. This means that you must have 2 Violets to breed Violet or 2 Sapphires to breed Sapphire. This sounds too easy so lets complicate it a bit.
You can also get a “Carrier”. This means that the chinchilla carries a gene for another colour but it is not visible. For instance, if you pair up a Standard with a Violet the baby will be a standard but will carry a recessive Violet gene. The gene is there but does not show in the appearance of the baby. When a carrier of certain colours is paired with a standard the babies can be the colour that is carried. This will not happen with Charcoal, Violet, Sapphire or Recessive Beige because they will always be dominated by the Standard. If you pair 2 Violet carriers for example, you can get a Violet baby if both parents carry over the Violet gene. Any baby of abovementioned Recessive colours will be a carrier. A chinchilla can also carry more than one recessive colour if bred to do so but then it gets even more complicated.
A word of advice on Violet and Sapphire. They carry the weakest genes. If you are ever lucky enough to own Violets or Sapphires it is much better to cross them with Standard to get strong carriers. Then you can pair them up with unrelated carriers to get stronger Violets and Sapphires. You will get less Violet and Sapphire babies but at least they will be strong and healthy. I’m a big advocate on quality over quantity and it would be terrible to have a bunch of weak and small Violets and Sapphires all over the show just to make money. That could mean the end of a good bloodline.
The best example of a carrier is Ebony (Black). Ebony is a weakly dominant accumulative gene and is expressed in various degrees of darkness. This will depend on how many generations of Ebony are bred in. Any baby of an Ebony parent is an Ebony Carrier. An Ebony Carrier can also give Ebony babies when paired with a Standard but the odds are that it will be a Light Ebony. There is however always the chance that it can be darker, although slim. When you pair up 2 Ebony Carriers it makes the Ebony gene stronger and you get darker babies. Two Ebonies will give you the most dark and darkest babies. A good example is my Ebony male. I paired him with 2 Standard females and from the 4 babies 1 was Dark Ebony, 2 was Medium Ebony and one was an Ebony carrier. Even if all the babies were Standard grey they would all be Ebony Carriers. This makes Ebony Carriers (or any carriers) very valuable for breeding.
Then you also get a LETHAL FACTOR. This is very important to know because it can cause your chinchillas great harm and permanent damage. The Lethal Factor exists for White and Velvet. When 2 White or Velvet genes meet it can cause the mother to reabsorb the baby back into her system. This can block one or both the tubes of her two-horned uterus from future breeding. The damage is permanent. If the baby is carried to term it will most probably die within a few days after birth. If it survives it will be small and weak. It is therefore not advisable to breed any 2 chinchillas which carry the white gene or any 2 which carry the velvet gene. Even if the 2 are not pure white or pure velvet the result will be the same. I spent hours looking for the results of pairing a White with a Velvet and could not find a conclusive answer. I spoke to someone who imported both White and Velvet and paired 2 of them up. The babies were small and weak and did not grow into big strong chinchillas. For now that is all I can say about pairing up White and Velvet but I will keep looking and will put it on the website if I find a satisfactory answer. Do not take the chance of playing with the Lethal Factor. The embrio can die at any stage of development and if it has already developed quite far and is not sucsesfully aborted can kill the female.
Remember that you get carriers of these genes also so good recordkeeping is a very important issue for any chinchilla breeder. I could also not find conclusive answers on pairing up eg. a White Mosaic with a Standard Grey White Carrier. It is said that the Standard gene allows for these to be paired up but I am still not convinced. The White mosaic carries both White and Standard genes and the Standard Carrier also. I believe that if both parents carry over the white gene you will have a lethal factor because white can’t exist in the homozygous state. The chance for this to happen is 25% and I’m not willing to take the chance.
If you want to play around with possibble different colour combinations and what colour babies to expect you can go to Silverfall Chinchilla Cross Calculator. Remember it is just an indication and nature is not predictable.I hope I didn’t cofuse you too much and haven’t said most of what can be said about genetics but it is a very complicated field and we as pet breeders should only know enough to keep our animals safe. I also don’t know much more but am happy with what I do know because I will not make any lethal mistakes.