Eva's Natal Rat Genetics Page

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Which genes causing colour varieties of the Natal Rat exists today?

Denna sida på svenska. Since the natal rat is a rather new species to keep as a pet there are not many colours and varieties known yet. And the genetics of the colours that do exist does not seem to be investigated.

  1. The first gene is the agouti gene A, which all my natal rats seems to have. I have not seen a natal rat that does have any mutation on the a-locus. The Agouti natal rat has a lighter coloured underside.

  2. Then we have a suspected brown gene b, giving the Cinnamon colouration. I do not know if this gene is scientifically described, but it works exactly like the brown gene on all other small pets. The photo shows a young Cinnamon baby. This has been the most common colour for many years in Sweden.

  3. I have heard that the albino gene c should exist, but I have still not seen any albino natal rat.

  4. I do have the pinkeyed gene p, which gives pink eyes and lighter yellowish/reddish body colour. I do not know if this gene is scientifically described, but it works exactly like the pinkeyed gene on all other small pets. The pinkeyed agoutis have a blue undercoat and the pinkeyed cinnamons do not, just like in mice and rats.

  5. Then I have the white-marked gene, which I will call W. This gene is actually co-dominant which is not that common in small pets! I have just testmated the gene to be sure.

    Any WW animal has lots of white on the head and rump, and any Ww animal has much less white, only a spot on the forehead and often no white at all on the rump, only a few spots on the underside. The WW I call Pied and the Ww Spot. (All my spots have also one white spot in each cheek, and many has a little white on the underside.)

    The photo shows two WW animals, of which one also is pp, and both are bb.

    The W gene seems to have some colour influence also, except for giving white markings, all my Pied Cinnamons (WWbb) have had a blue cast as younger animals that disappears as they grow up. None of my Cinnamon Spot (Wwbb) and Agouti Spot (Ww) have shown this effect.


Co-dominance

It is easy to determine that this gene is co-dominant when you do the correct test-mating:
  1. If the gene had been dominant all my babies from the cross between the high grade white-marked Pied variety and the non-marked variety had been exactly like the high grade white-marked Pied variety, with all white heads and white rumps.

  2. If the gene had been recessive all babies from this cross had been non-marked.

  3. When as I did see a new phenotype appear (in this case low grade white markings instead of no white or high grade white markings) in such a cross you know that the gene is probably co-dominant.

Copyright Eva Johansson.
Last update: 13th of April 2007.