trabots wrote:I also haven't a clue why there are 2 choices ('x1,x2') for split sex linked males. Anybody?
Willy, this is where you're crossing over comes into play. The simplest example to grasp is with ino and cinnamon, which are extremely hard to cross over in the first place. So, how can you breed a male that splits for both ino and cinnamon? In two ways.
Option 1:
green ino x green cinnamon (or green cinnamon x green ino).
Here, one mutant gene is inherited from each parent. This offspring male will be used to breed a hen where crossing over occurs.
Option 2:
green x green cinnamon-ino
Here both mutant genes are inherited from a single parent, i.e. the mother is a bird where cinnamon and ino has crossed over.
If two different mutations occurs in the same chromosome, this becomes important. Also what we see with dark and blue, and I suspect with grey and "bronze" fallow. I'm not sure why they distinguish between this X1/X2 and T1/T2, as they do the same thing. Probably because X1/X2 occurs on the Z-chromosome (sex-linked).