Genetic Inheritance Questions

[loveourbirds]

Barring cannot "become" a sex-linked gene, it IS one. Female birds have only one copy of sex-linked genes. Their alternative chromosome is the W chromosome, which does not have a space for sex-linked genes. Thus they can be B/- (barred) or b+/- (not barred). If they have two barring genes, they are male, as they have two Z chromosomes. Males can be B/B (barred with wider white bars), B/b+ (barring is the same as female barring) or b+/b+ (not-barred).

There is no recessive barring gene, Dominant white birds tend to have multiple dilution genes bred into them. Barring, blue and silver are common. They help turn a dominant white bird a solid white, which it is often not without the addition of genes that dilute or remove colour. Black sex-links are bred from a barred mother and a non-barred father. The male chicks will all receive a copy of barring from the mother, the girls will receive the W-chromosomes absence of a place for a second copy of any sex-linked genes. California greys have a different allele of the same barring gene (B^Sd) that dilutes as well as creates a white bar.

you had mentioned earlier that if a barring gene was present it would show, i just wanted to show the exceptions to the rule.

a very well known local poultry judge once told me you dont have to understand the genes to breed good quality chickens, just breed toward the traits you want. when cross breeding to improve color or type its best to use a breed or color that was used in the original mix. that being said, there are genes that will not always breed true as you have mentioned. i know the fawn gene in oegb's drove me nuts at first, i thought they would all come out fawn.

 

[Sonoran Silkies]

Quote:

There is no recessive barring gene, Dominant white birds tend to have multiple dilution genes bred into them. Barring, blue and silver are common. They help turn a dominant white bird a solid white, which it is often not without the addition of genes that dilute or remove colour. Black sex-links are bred from a barred mother and a non-barred father. The male chicks will all receive a copy of barring from the mother, the girls will receive the W-chromosomes absence of a place for a second copy of any sex-linked genes. California greys have a different allele of the same barring gene (B^Sd) that dilutes as well as creates a white bar.

you had mentioned earlier that if a barring gene was present it would show, i just wanted to show the exceptions to the rule.

a very well known local poultry judge once told me you dont have to understand the genes to breed good quality chickens, just breed toward the traits you want. when cross breeding to improve color or type its best to use a breed or color that was used in the original mix. that being said, there are genes that will not always breed true as you have mentioned. i know the fawn gene in oegb's drove me nuts at first, i thought they would all come out fawn

I did not mention the hypo/epistatic possibilities that Tim just covered, so perhaps I erred in that. My point was that you implied that barring is recessive to not-barring, and that females can have two copies of the gene.

Fawn has one copy of an incompletely dominant gene (dun), so how it is bred determines the percentage of offspring that are fawn.