Pea Comb & Blue Egg Gene

[PippinChicken]

I just hatched some Olive Eggers (Ameraucana x Marans, variety of generations and back crosses) and don't have any interest in keeping ones who will end up laying brown eggs. I read that in Ameraucana based Olive Eggers, if they have a pea comb then they also have the blue egg gene. Is this true 100% of the time? I wouldn't want to prematurely get rid of anyone based on comb type!

 

[R2elk]

I just hatched some Olive Eggers (Ameraucana x Marans, variety of generations and back crosses) and don't have any interest in keeping ones who will end up laying brown eggs. I read that in Ameraucana based Olive Eggers, if they have a pea comb then they also have the blue egg gene. Is this true 100% of the time? I wouldn't want to prematurely get rid of anyone based on comb type!

I would not bet any money on it. Egg genes and comb genes are two entirely different things.

 

[TheKindaFarmGal]

I would not bet any money on it. Egg genes and comb genes are two entirely different things.

Agreed. I have both single and pea combed chickens that lay blue and green eggs.

 

[PippinChicken]

Agreed. I have both single and pea combed chickens that lay blue and green eggs.

That's interesting, are they Ameraucana crosses or from a single combed blue layer? The explanations I'd read were that while they are obviously different genes, in Ameraucanas they are very closely linked so it's unlikely for the offspring to inherit one without the other. But even if that is accurate, I've got no idea how the varying generations and back crosses may change things

 

[R2elk]

That's interesting, are they Ameraucana crosses or from a single combed blue layer? The explanations I'd read were that while they are obviously different genes, in Ameraucanas they are very closely linked so it's unlikely for the offspring to inherit one without the other. But even if that is accurate, I've got no idea how the varying generations and back crosses may change things

They are not linked. They both just happen to be dominant genes meaning that it only takes the presence of one copy of the gene for the trait to be displayed.

 

[TheKindaFarmGal]

That's interesting, are they Ameraucana crosses or from a single combed blue layer? The explanations I'd read were that while they are obviously different genes, in Ameraucanas they are very closely linked so it's unlikely for the offspring to inherit one without the other. But even if that is accurate, I've got no idea how the varying generations and back crosses may change things

They are mixes of mixes. I live in South America - Brazil - and it is very hard to find purebreds (of any breed).

Here's one of my hens, single combed and lays beautiful blue eggs. I am currently doing some breeding for egg color, one of her daughters is pea combed and lays very nice blue eggs as well.

 

[Sicilianu]

It is a fact that the pea comb and blue egg gene are relatively closely linked on Chromosome 1 of the chicken genome. What does this mean? If you cross a pure pea-combed, blue-egged individual with a pure single-combed, white-egged individual, 1st generations should all be pea-combed and lay blue eggs because both genes are dominant.

If the 1st generation are bred to each other to make a F2 generation, most pea-combed individuals will lay blue eggs and most single-combed individuals will have white eggs.

Below is a graphic of a few individuals from this cross.

Individuals 1, 2, and 3 would all have peacombs and lay blue eggs. Individual 3 has a "cross-over" between it's two chromosomes but still will have a peacomb and lay blue eggs. In the next generation, this individual could have daughters that have single combs and lay blue eggs or peacombs and lay white eggs because the linkage has become switched.

Below is an example of a couple of the minority of "cross-over" events in the 2nd generation or later where the hen has a single comb and lays blue eggs or has a peacomb and lays white eggs.

It is important to know what breeds you are starting off with in all this. For instance if you are crossing a legbar (which has the single-combed gene linked with blue eggs) and Cubalayas (which has the peacomb gene linked with white eggs), then the genes will be linked opposite to the examples above.

However if you are crossing an Ameraucana (which has the peacomb gene linked with blue eggs) and leghorn (which has the single comb gene linked with white eggs) it will follow the examples above.

If you are dealing with Easter eggers which are a mixed bag of generations of crossing, the deck will already be shuffled a bit so it is more unpredictable.

Basically the moral of the story is that these two genes will travel together the majority of the time but there will always be recombinations between the two in crossing them, leading to the opposite combos.

Here is a short research article to back this up and there are others as well. https://science.sciencemag.org/content/90/2326/88

 

[Perris]

If you cross a pure pea-combed, blue-egged individual with a pure single-combed, white-egged individual, 1st generations should all be pea-combed and lay blue eggs because both genes are dominant.

As it happens, I currently have 4 chicks of such a cross. They are just over 2 weeks old and combs are not apparent yet, but I'm hoping any pullets amongst them will lay blue eggs. If all do I'll be delighted!

 

[nicalandia]

They are not linked. They both just happen to be dominant genes meaning that it only takes the presence of one copy of the gene for the trait to be displayed.

I often wonder why people like these "Educators" can say this with such a certainty when a quick google search will yield multiple research from renown scientists and researchers that will say otherwise. Please take a moment to research before posting erroneous statements.

 

[Perris]

can you @nicalandia please explain it then in terms someone not versed in modern genetics can understand? It is looking like 2 of my araucana x SFH crosses have single combs, and 2 of them pea combs. I have been reading chicken genetics threads and papers, and it is really hard for me to follow. A lot has changed since I did A level biology!