Affiliated to the National Hamster Council
In hamsters, as in all mammals, the gender of an individual depends on the chromosomes inherited from its parents. Females have a pair of X-chromosomes, (XX), one inherited from each of their parents. Males have one X-chromosome, (inherited from their mother), and a Y-chromosome, (inherited from their father). Since the Y-chromosome is a "cut down" version of the X, any genes present on the section of the X-chromosome that is absent in the Y may behave differently in males and females. The Yellow gene, To, is the currently the only "sex linked" gene in Syrian hamsters, and produces the Tortoiseshell. Combining this Tortoiseshell patterning with the White Patterning genes, (Banded or Dominant Spot), give the Tortoiseshell and White. As with other Banded or Dominant Spotted animals, it is not always a good idea to mate a Tortoiseshell and White to a Banded or Spotted male; a plain coloured mate will give a mixture of youngsters with or without white.
The Yellow gene is "co-dominant"; animals will show the Yellow gene if they have a copy, but will also show the "non-Yellow" gene if they have a copy. Males, having only one X-chromosome, can have an X-chromosome with the Yellow gene, (XTo), or with the opposite, "non-yellow" gene, (Xto). They will show whatever genes they possess, so XTo will give a Yellow male and Xto will give a non-Yellow one. Since the Yellow gene combines with Cinnamon to give Honey and with Dark Grey to give Smoke Pearl, this also applies to these colours.
With females, the situation is slightly different. As with males, they show the genes that they have, but they have TWO copies of the X-chromosome. A Yellow female only shows Yellow - so her X-chromosomes are both XTo. A non-Yellow female shows no Yellow at all, so her X-chromosomes are both Xto. Some female hamsters, however, (Tortoiseshells), show a mosaic of Yellow and non-Yellow patches in their fur. This is because they have inherited a "Yellow" X-chromosome, ( XTo), from one parent and a "non-Yellow" one, (Xto), from the other. Tortoiseshell and White individuals have a third colour - white - because they have inherited a "pattern" gene, (either Banded or Dominant Spot), as well.
Since Yellow combines with other genes to produce different colours, the "Yellow"
patches on different coloured Tortoiseshell and White hamsters vary as well.
For example, on a Golden Tortoiseshell and White, the patches of fur are Golden,
White and Yellow, while on a Dark Grey Tortoiseshell and White they are Dark
Grey, White and Smoke Pearl. The Yellow patches on a Cinnamon Tortoiseshell
and White are Honey, but perhaps the most striking colour of Tortoiseshell and
White of all is the Black Tortoiseshell and White, with patches of Black, White
1. A tortoiseshell is a sex-linked bi-coloured animal. The standard calls for a tricoloured animal which is produced by combining the tortoiseshell with a white pattern gene. The coat colour shall consist of a balanced pattern of coloured, yellow and white patches. These patches shall be clear and distinct with no brindling.
2. The coloured areas shall conform to the recognised full colour variety whilst the yellow shall be a rich creamy yellow when in combination with the golden, but shall be present in a diluted form when combined with other recognised colours. e.g.
|Golden||Rich apricot yellow|
|Dark grey||Smoke pearl|
3. The belly fur shall be white.
4. Eye colour: as stipulated for the full colour variety; also red/ruby eye or eyes permissible.
3. Ear colour: as stipulated for the full colour variety; also flesh or partly flesh coloured permissible.
NOTES - Sex linked.
Copyright© Midland Hamster Club (UK)