Dear Muridea,
Those are very interesting observations.
It is unlikely that you discovered a non-lethal version of the Sp-allele,
because a gerbil which is homozygous spotted (if it survived) would appear
as a black-eyed white. The latter option would be much more likely, because
there is a similar gene-pair in the house mouse: W (which is also lethal
when homozygous) and s (influences spotting patterns in combination with W
and produces spotting itself, when in homozygous state).
I think that the spotting modifiers are also responsible for the white
patches on the throat of black gerbils.
I would be very interested in the exact breeding data. Could you provide me
with it?
----- Original Message -----
From: "Muridea" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, May 04, 2001 3:49 AM
Subject: White Spotting- genetic question
I want to know has anyone had this happen, is this normal or not. I have
been selecting in one line for lots of white and roaning of colour on the
back. I began with a gerbil that just had a headspot and partial colour-
not very impressive- yet in a few generation of careful selection i have
gotten to gerbils with patches of colour just around the ears, the white
colour extending to midbody and the remainer of the rump coloured but
extreemly roaned so that it looks almost like a chinchilla colour.
Here is what I find odd though- Sp is dominant and homozygous lethal. I am
breedign spotted to spotted without any problems. Theoretically I SHOULD
get some solid coloured gerbils (about 1/3rd the litter actually born) but I
dont. Every gerbil is either "extreem" spotted (as described above) or
reverted to the original spotting pattern of the original spotted female -
just a head spot with partial collar and no roaning of colour on the rump.
My litters also tend to be about 6 babies each but then again, so do most of
my non-spotted gerbil's litters- I was expecting smaller litters but it
hasnt happened....
Any idea why this happens (no solid coloured gerbils and no significant
change in litter size)? My first thought was a non-lethal variation of the
SP allele. My next idea was that i had overselected for spotting modifiers
that when brought all together manage to make spotted gerbils without the
actual SP gene present? Any other ideas?
AG
