Those tan piebald merles are so nice; I keep thinking about them...how did you improve the tan bellies? Or are they two completely different lines? Just wow. I agree with Rhaputin; they are just stunning! I'll stop by and fill my pockets one of these years.
the red bellies of tans depend on the amount of pheomelanines. In Europe the variety with more than 100 years of selection for pheomelanine enhancing or enriching factors is dominant red (Ay/*). As discussed elsewhere the Ay/* often have health problems or are at least fat and infertile, but since they are a lethal mutation, they never breed true. You always get some A/* instead of Ay/* from breeding dominant reds, even when you breed Ay/* x Ay/*. These Agoutis are called Golden Agouti, because they carry the pheomelanine enhancing factores without the health problems.
We are sure that in Europe the good tan lines (good means dark bellies here, not good type) have some Ay or Golden Agoutis in the ancestry.
Since there are very dark Ay/* and Golden Agoutis in the US now (Jack Garcia) it will be only a question of time until the tan bellies improve in the US very much too.
As mentioned before elsewhere, I think dominant reds should not be bred for the broad mass of mouse lovers and pet shops, but they are of course valuable "material" in the hands of experienced breeders like Jack, and I trust on his skills as a breeder and his knowledge of human nature ;-)
Ok, back to the question: I got one single tiny merle buck from the USA only. This single buck is the forefather of all Merle in Europe. I crosed him to seven not related European showtype mice to get several lines and since I thought merle is dominant, I hoped to get many merle offspring, but I got hundreds of black mice only. After several backcrossing experiments I noticed that the variety of merle, which is here, is recessive. It took some time, but I used and still use the following method to improve them:
Merle x Good Tan -> pale bellies in F1, only black (tans), no merle, but all are carriers for merle.
F1 x F1 -> F2 = Some Black Tan merle.
Black Tan merle from F2 x Good European Black Tan with dark belly -> only black (tans), no merle, but all are carriers for merle, and the bellies are a little better...
... and so on and on in circles.
Best regards, Roland
Chilloutarea Mousery - Tricolor , Splashed , Merle , Recessive Red
The place where science meets fun!