www.ehow.com/how_5268673_breed-star-black-star-chickens.html
Ah, I see where you got your information. I'm afraid it's one of those cases where the particular webpage is wrong. Perhaps it would be easier if I try to explain why.
All genes, except except sex genes on the sex chromosomes, come in pairs. One gene inherited from each parent. Genes can be dominant or recessive, meaning generally, the dominant gene shows & the recessive gene is hidden. Other genes are what is called incompletely dominant (& incompletely recessive), this means the result of te two different genes shows as an intermediate of the two genes.
Right.......white leghorns have a pair of genes known as dominant white. Dominant white stops black pigment only. The absence of pigment showing a white. They also have a pair of genes called extended black, which means that if the white leghorns had not had the dominant white genes they would have been all black.
Now RIR, in the place where the white leghorns have their black genes, the RIR have a pair of genes called wheaten,wheaten is recessive to extended black. Of course both breeds have lots of other genes but they are not relevant to this particular cross.
So.....when one crosses white leghorn & RIR the offspring inherit one extended black gene & one wheaten gene; the extended black gene is dominant, the wheaten gene does not show it is recessive. This would make the offspring all black.
But the offspring have also inherited a dominant white gene from the white leghorn & a non domiant white gene from the RIR. So the single dominant white gene from the leghorn stops the black pigment from being laid down in the feather so all of the the offspring are white.
(There is also leakage of red due to the offspring not being "pure" for extended black & also black flecks because the bird is not "pure" for dominant white).
Ah, I see where you got your information. I'm afraid it's one of those cases where the particular webpage is wrong. Perhaps it would be easier if I try to explain why.
All genes, except except sex genes on the sex chromosomes, come in pairs. One gene inherited from each parent. Genes can be dominant or recessive, meaning generally, the dominant gene shows & the recessive gene is hidden. Other genes are what is called incompletely dominant (& incompletely recessive), this means the result of te two different genes shows as an intermediate of the two genes.
Right.......white leghorns have a pair of genes known as dominant white. Dominant white stops black pigment only. The absence of pigment showing a white. They also have a pair of genes called extended black, which means that if the white leghorns had not had the dominant white genes they would have been all black.
Now RIR, in the place where the white leghorns have their black genes, the RIR have a pair of genes called wheaten,wheaten is recessive to extended black. Of course both breeds have lots of other genes but they are not relevant to this particular cross.
So.....when one crosses white leghorn & RIR the offspring inherit one extended black gene & one wheaten gene; the extended black gene is dominant, the wheaten gene does not show it is recessive. This would make the offspring all black.
But the offspring have also inherited a dominant white gene from the white leghorn & a non domiant white gene from the RIR. So the single dominant white gene from the leghorn stops the black pigment from being laid down in the feather so all of the the offspring are white.
(There is also leakage of red due to the offspring not being "pure" for extended black & also black flecks because the bird is not "pure" for dominant white).
