x1 x2 ???

[Lushen1600]

Quick question on the genetic calculator under the sex-linked males, there are 2 options for splits x1 and x2, I have always used the x1 option and wanted to know what the x2 option was for as when you use it, it doesn't make any difference to the results of my calculations, so could someone shed some light on why the calculator has these options and how would one use them

Thanks
Lushen

[rod038]

From what I understand it depends on where the Sex linked split came from. Which parent gave the Cock bird the split. X1 means split was from father and X2 means split was from mother. Doesnt mean much until you start talking multiple splits and then its possible for what they call crossovers.

Example 1 - Pallid Cock x Green Hen would give you Green / Pallid Cock - This would be X1 because split came from Cock.

Example 2 - Green Cock x Pallid Hen would give you Green / Pallid Cock - This would be X2 because split came from Hen.

[Lushen1600]

Ok thanks for the reply, I now understand but whether you use x1 or x2 in your calculations, the results seem to be the same.

Thanks
Lushen

[rod038]

Yes they will be the same for 1 mutation but when you have a bird with multiple sex linked mutations there are chances of what they call crossing over and that is where this comes into the calculations. Its rare and its complex.

[Johan S]

Lushen, I'm no expert but I think Rod has it spot on. It depends on two sex-linked mutations, not one. E.g. you have a split bird from a lutino x cinnamon pair. This means that one mutations goes as X1, the other as X2. When you compare the outcome of a green / ino (X1) cinnamon (X2) x green, the chance for a cinnamon ino (the crossover, i.e. ino (X1) cinnamon (X1, not X2 as previously...)) is 1.5%. Compare with the breeding result of a green / ino (X1) cinnamon (X1) x green where you will easily breed the crossover.

I.e., it is like saying 'an offspring inherits TWO mutations (X1 X1) from ONE parent, and NONE from the other', vs. 'an offspring inherits TWO mutations, ONE mutation from the father (X1), and ONE mutation from the mother (X2)'.

[Lushen1600]

Thanks Rod and Johan for ur replies, yes I see what you mean with the difference in percentages when you use x1x1 and when you use x1x2, makes so much more sense now

Thanks
Lushen