Originally Posted by jailbird
This is not to discourage or contradict anyone but no matter what numbers are used it seems to me that a cross is a cross. And the progeny will always exhibit traits from both or all branches of the families with dominance being the biggest influence.
Even if it's 1/16 this and 15/16 that if the original traits of both parties were used in line breeding. Then the progeny will still be as mixed up as the first generation half and half. Maybe it gets more and more difficult to get the opposite traits but it would still be there.
To "purify" more or less, you will need to chose the male offspring that looks most like his mom in phenotype. Mate him back and again choose the male that most resembles the mom again. Eventually all the offspring will all be pure to the traits of the mom.
The opposite can also be done with the females to the dad.
When none of the other traits come out again then you have a pure line ;-)
Rejoinder: this is true only if the parent you are purifying to is pure for those traits in the first place. If they were crossed for those traits then the offspring will never be pure.
You will have better chances by mating brother sister with exactly the same traits you like. And carry on that way untill no other trait comes up outside of your specified phenotype.
But thats just my "theory" extrapolated from my limited breeding experience.
"And the progeny will always exhibit traits from both or all branches of the families with dominance being the biggest influence."
I agree, the crosses will always exhibit traits from both lines, but in my breeding experience when you breed 3/4 and 1/4 crosses for example Hatch Clarets, at 3/4 hatch they hit harder but at 3/4 claret they cutt better, in the hatch/claret case 1/2 and 1/2 was the best cross.
but in the case of hatch/roundheads the 1/2 and 1/2 were good but the 3/4 hatch 1/4 roundhead could eat the 1/2 and 1/2's for breakfeast
I think it all goes back to it depends on the line