Chinchilla genetics
The aim of this page is to provide a reference for anyone who is interested in genetics of the chinchilla breed. I have gathered information from various sources including Cavies magazine publication, the British Cavy Council and experienced exhibitors and breeders, in addition to my own knowledge as a biologist. It does not aim to introduce genetics - may I point anyone interested in learning more, to the British Cavy council genetics article , which includes the basics through to more advanced genetics or BBC bitesize, a great overview of GCSE level genetics and DNA.
However I will just point out 2 terms I use throughout
'genotype' - the actual genetic make up of the cavy, what genes they carry
'phenotype' - what the cavy actually looks like, its physical characteristics.
PLEASE let me know if you have any queries or spot any errors - I am happy to be corrected!
To date, it appears that the four chinchilla's basic genotype we are aiming for is:
White/ Grey -Silver - AABbcrcrEEPP
Cream/Grey - Lemon - AABbcdcrEEPP
White/Chocolate - Cinnamon - AAbbcrcrEEPP
Cream/Chocolate - Cream - AAbbcdcrEEPP
(Explanation of colours and photos can be found here if you missed it)
I describe this as 'basic' genotype as I have ignored other genes that are not typical to the chinchillas - I have streamlined the important ones. Such examples of genes include the rex (Rx), spotting (S) Length (L), Rough (R) and its Modifiers (M) and many others, all characteristics which are not desirable in chinchilla standard. Chinchillas have a smooth coat which is:
rrMMLLRxRxTTcucuststSnSn. As this is assumed, I have removed these from the above genotype. Of course it may be possible that a few recessive genes are lurking and will pop out from time to time, however these are not generally then used further in breeding programmes.
Of course it is possible to produce a crested or long haired chinchilla for example, but I am not addressing this here.
All of this is still a work in progress and many chinchilla cavies do not have this ideal genotype. This is mainly due to the way in which chinchillas are produced and outcrossed to other varieties, such as selfs or argentes, both of which carry recessive genes such as ee or pp. I will continually update this page as and when I have time and as we develop our knowledge.
Agouti (A)
AA denotes long ticking, however it is likely that some are Aa having been selected for long ticking; however, Agoutis are Aa which produces shorted ticking.
Black (B)
In terms of silver and lemon chinchillas, it is not sure whether the genotype is in fact BB or Bb for certain. Carrying the chocolate gene (Bb) is may produce a lighter coat colour and therefore more desirable, but for many this is not the case (show winning agoutis have been known to carry Bb without effecting their dark undercoat).
C (colour dilution) series
cr - ruby eye dilution (dilutes red to white) appears to be carried by all chins. White ticked chins carry two copies; cream ticked chins carry one of cr and one copy of cd - this light dilution dilutes red to buff. Therefore, it is possible to produce a buff chinchilla (cdcd), which although is not correct to show, it maybe useful as breeding stock.
Extension (E)
Allows black pigment throughout the coat. Although the above genotype specifies EE, it is likely that many still carry Ee due to the fact that occasionally selfs (ie those with ee) are found in litters. I am unsure the effect of Ee (if any) despite the fact that E is dominant
Pink eye (P)
It is assumed chinchillas are PP. Again, I am unsure whether any are Pp and if they are, what effect this may have. please let me know if you have any thoughts on this! * Edit Jan 2019 - it seems as though I have Pp in a couple of my pigs (or had, RIP Solstice) which has given rise to Argente (basically genetically pink eyed chinchillas). The sow was particularly light in colour and not showable.
References:
1) Breeds in focus: The chinchilla (2105) Cavies Magazine issue 275
2) Cavy Genetics: An Exploration (2008, 2018) British Cavy Council website. Originally written by Nick Warren, 1999; Revised and updated by Bryan Mayoh, with input from Simon Neesam, 2008. Revised and reprinted in Cavies 2018
3) Simon Neesam (2015) Personal communication
4) Sue Ford (2015) Personal communication
However I will just point out 2 terms I use throughout
'genotype' - the actual genetic make up of the cavy, what genes they carry
'phenotype' - what the cavy actually looks like, its physical characteristics.
PLEASE let me know if you have any queries or spot any errors - I am happy to be corrected!
To date, it appears that the four chinchilla's basic genotype we are aiming for is:
White/ Grey -Silver - AABbcrcrEEPP
Cream/Grey - Lemon - AABbcdcrEEPP
White/Chocolate - Cinnamon - AAbbcrcrEEPP
Cream/Chocolate - Cream - AAbbcdcrEEPP
(Explanation of colours and photos can be found here if you missed it)
I describe this as 'basic' genotype as I have ignored other genes that are not typical to the chinchillas - I have streamlined the important ones. Such examples of genes include the rex (Rx), spotting (S) Length (L), Rough (R) and its Modifiers (M) and many others, all characteristics which are not desirable in chinchilla standard. Chinchillas have a smooth coat which is:
rrMMLLRxRxTTcucuststSnSn. As this is assumed, I have removed these from the above genotype. Of course it may be possible that a few recessive genes are lurking and will pop out from time to time, however these are not generally then used further in breeding programmes.
Of course it is possible to produce a crested or long haired chinchilla for example, but I am not addressing this here.
All of this is still a work in progress and many chinchilla cavies do not have this ideal genotype. This is mainly due to the way in which chinchillas are produced and outcrossed to other varieties, such as selfs or argentes, both of which carry recessive genes such as ee or pp. I will continually update this page as and when I have time and as we develop our knowledge.
Agouti (A)
AA denotes long ticking, however it is likely that some are Aa having been selected for long ticking; however, Agoutis are Aa which produces shorted ticking.
Black (B)
In terms of silver and lemon chinchillas, it is not sure whether the genotype is in fact BB or Bb for certain. Carrying the chocolate gene (Bb) is may produce a lighter coat colour and therefore more desirable, but for many this is not the case (show winning agoutis have been known to carry Bb without effecting their dark undercoat).
C (colour dilution) series
cr - ruby eye dilution (dilutes red to white) appears to be carried by all chins. White ticked chins carry two copies; cream ticked chins carry one of cr and one copy of cd - this light dilution dilutes red to buff. Therefore, it is possible to produce a buff chinchilla (cdcd), which although is not correct to show, it maybe useful as breeding stock.
Extension (E)
Allows black pigment throughout the coat. Although the above genotype specifies EE, it is likely that many still carry Ee due to the fact that occasionally selfs (ie those with ee) are found in litters. I am unsure the effect of Ee (if any) despite the fact that E is dominant
Pink eye (P)
It is assumed chinchillas are PP. Again, I am unsure whether any are Pp and if they are, what effect this may have. please let me know if you have any thoughts on this! * Edit Jan 2019 - it seems as though I have Pp in a couple of my pigs (or had, RIP Solstice) which has given rise to Argente (basically genetically pink eyed chinchillas). The sow was particularly light in colour and not showable.
References:
1) Breeds in focus: The chinchilla (2105) Cavies Magazine issue 275
2) Cavy Genetics: An Exploration (2008, 2018) British Cavy Council website. Originally written by Nick Warren, 1999; Revised and updated by Bryan Mayoh, with input from Simon Neesam, 2008. Revised and reprinted in Cavies 2018
3) Simon Neesam (2015) Personal communication
4) Sue Ford (2015) Personal communication