Hypothetical question about dominant genes. Help me learn genetics!

[FowlWitch]

I'm curious as to what would happen if you had a chicken with 2 copies of one dominant gene (example may be dominant white, so WW) bred to a second chicken with 2 copies of a different dominant gene (example may be black, so BB). What would that create in the chicks who are born with BW genetics? A black and white chicken, gray chicken, or something else?

I'm not asking for any specific reason other than curiosity as I'm not currently breeding, so there's no real world application for this at the moment.

 

[The Moonshiner]

Dominant is all relative to what other genes are in play.
A dominant gene doesn't mean its actually dominant over all other genes or any amount of genes really.
Some dominant genes will be dominant over other genes and hide them or cover them. Others will cover them allowing some of the underneath gene leak through. While still others will be covered themselves by another gene.
Its more of an order of dominance or a matter of how certain genes effect or interact with other genes.

 

[FowlWitch]

Dominant is all relative to what other genes are in play.
A dominant gene doesn't mean its actually dominant over all other genes or any amount of genes really.
Some dominant genes will be dominant over other genes and hide them or cover them. Others will cover them allowing some of the underneath gene leak through. While still others will be covered themselves by another gene.
Its more of an order of dominance or a matter of how certain genes effect or interact with other genes.

Cool, thank you for answering

 

[MokiYoki]

Ok so this might be the weirdest advice but, if you play minecraft download my mod. Ive added a full genetics system based on real life ESPECIALLY so for the chickens. There is a genes debug book and I can show you how it works. Crossing black chickens to white, how you get a grey chicken, barred chicken, ect. Cause Im not sure how else to explain it all.
https://www.curseforge.com/minecraft/mc-mods/enhanced-animals

 

[CountryFlock]

A black chicken isn’t determined by a black gene.
A black chicken is determined by extended black [E/E] plus other melanizers. Could also be birchen.

For whiteness in chickens it’s determined by recessive white, dominant white, and 2x dominant white.

Now when you say white chicken to a black chicken makes a gray chicken- that’s incomplete dominance. An example of that in chickens is the blue gene.
(b/b) = Black
(B/b) = Blue
(B/B) = Splash

Try playing around with this calculator here:
http://kippenjungle.nl/breeds/crossbreeds.html

 

[Amer]

It will actually be
Ii+EE
Because the two genes are not on the same locus. The white has black under it, so it will still have two copies of black.
But white is dominant over black on the i locus.

Black is a phenotype, not a gene.
Dominant white is a gene, not a phenotype.

A bird that is Ii+EE will be paint, white with black markings.

 

[nicalandia]

I'm curious as to what would happen if you had a chicken with 2 copies of one dominant gene (example may be dominant white, so WW) bred to a second chicken with 2 copies of a different dominant gene (example may be black, so BB). What would that create in the chicks who are born with BW genetics? A black and white chicken, gray chicken, or something else?

What you are searching for is Incomplete Dominance vs Codominance:

In both codominance and incomplete dominance, both alleles for a trait are dominant. In codominance a heterozygous individual expresses both simultaneously without any blending. An example of codominance is Dominant White, when in heterozygous form both White and Black feathers are expressed. In incomplete dominance a heterozygous individual blends the two traits. An example of incomplete dominance is the Blue mutation, when in heterozygous form the color is a blend of both White and Black turning the bird gray colored.

An example:

codominance of dominant white: Erminette Pattern(Dominant White on extended black, basically your WB)

 

[nicalandia]

Interestingly enough when two incomplete dominant traits like Dun(I^D/i+) and Blue(Bl/bl+) are combined you get what Mr. Henk named: Platinum Blue

Platinum blue Sumatra:

 

[The Moonshiner]

Not a big fan of the last few posts talking about crossing a white bird with a black bird to create a gray bird.
Sounds like mixing paint which isn't how it works with chickens.
I'll stand by the statement that crossing a white chicken with a black chicken will not make a gray chicken, period. Nor will it make a blue chicken.
There's different genes that can make a chicken white and none will blend with black to make gray.
You may very well make a blue chicken with a splash chicken which may appear whitish but it isn't white and IMO using the term white for a genetically splash chicken is gonna confuse some members that are reading these posts.

 

[nicalandia]

Not a big fan of the last few posts talking about crossing a white bird with a black bird to create a gray bird.
Sounds like mixing paint which isn't how it works with chickens.

Was addressing the OP about the difference between Incomplete dominance and Codominance, and While Splash my not look entirely white on Extended black background it's one of the best example of it's codominance effect, we all are aware that things are so simple in chicken genetics.

Splash has real hard time diluting the black pigment in Extended Black birds, so let's use other backgrounds for example Splash laced red, the lacing on them looks completely white right? so if we cross that with a Black Laced Red we get the gray/blue laced red products, this is proof that the Blue Splash gene is incompletely dominant and not codominant.