The best from my pet x show litter

you may of greatly improved the type on the mice this cross has thrown, however the mice so produced will all carry as recessive or indeed dominant all the poor type of their parents. you now need to breed the young together , getting rid of all such mice that show poor type. Mating back to a typy parent will greatly increase the concentration of genes that you want.

Type is not a matter of recessive and dominant genes. Getting a type you want is a matter of selection. These babies are for my merle project so they will be bred together then the resulting offspring to a show mouse.

Treat it as such my dear and you will acheive your goals much quicker. I did not mention genes for type. I did mention concentrating up the minor modifiers that are closely attached to the genes. I would suggest you treat the modifiers as dominant or resesive in relation to each other. you will learn much that way .

Sounds like you have a good plan, Bryana.

I think what I'll be back means is that while it may not be, necessarily, a cut and dry dominant vs. recessive on type, things can lurk hidden for a long time in the genetics of the mouse.

For example, a few years ago when breeding from a line bred colony of KK mice X a pet store mouse, (which was basically F1: KK X Pet Store Mouse, F2: F1 X F1, F3: KK X F2, F4: F3 X F3), in the F4 generation I had a mouse pop up with an extremely short, thin tail. Despite the fact, that none of the mice bred for 3 generations had anything like that (all tails were, at least, an inch longer than the body). Naturally, the one with the short tail was culled immediately, but those negative traits can lay hidden for several generations and pop up a lot later on.

Its just a thought to keep in mind while breeding.

Typy-ness is a matter of degree and proportion, which of course is in the genes, but to say those characteristics are dominant or recessive is misleading...ears and tails and all other parts of the mousie are not governed by one gene but a wide variety of genes in which there is a gradual additive or subtractive factor for each feature. Great changes in type can be got by breeding average meeces to show meeces, and then choosing for best features for future pairings or breeding offspring back to a typy parent. Even with purebred show lines that have generations of history behind them there are some that are more typy and some that are less so, or else show breeders wouldn't need to cull.

Even with purebred show lines that have generations of history behind them there are some that are more typy and some that are less so, or else show breeders wouldn't need to cull.

Click to expand...

Very true, but with those pure lines the chances of such a dramatic throwback (like tiny ears or an extremely short tail) would be a lot less likely. The mice are constantly improving because they are culling the worst and breeding from the best only, so that each generation the differences are very slight in comparison to a pet store typed mouse popping up in a show breeders lines (by definition a U.S. pet store typed mouse vs. a UK show mouse).

And as you said its a case of lots of modifiers, so with all of the offspring carrying some of those modifiers, breeding back in to the siblings (vs. the show parent) can cause those modifiers to present themselves more frequently.

Its more of a challenge to breed them out, but not impossible.