Theory: Ml and id+ cause brown eyes in chickens

[SourRoses]

Then, I went a reread what F.B. Hutt wrote on the topic in his classic “Genetics of the Fowl” Pg 489: “MacArthur (1933) added similar data for a dominant gene Br, which causes a light iris, ranging in color from yellow-orange to bay, in contrast to the brownish-blackish iris.” This quote came from a small subchapter titled “the chromosome map”. It listed the following genes to be linked to this recessive sex-linked light eyed gene Br: K (slow feathering); S (silver); Li (light down); Id ( Inhibitor of dermal melanin- you may be right about this one @Amer !); B (barred); and Ko (head streak).

Thank you for the effort of sharing that, very interesting!

I'm hoping to keep the black eyes in my project, so I was curious about this thread.

As an aside: What is head streak?

 

[KristenG]

Thank you for the effort of sharing that, very interesting!

I'm hoping to keep the black eyes in my project, so I was curious about this thread.

As an aside: What is head streak?

I was not sure on the head streak. The first thing that came to mind was the stripe on the back of the head in chick down like on this BBR d’Anvers:

So I looked up head streak in Hutt and in page 214 it did talk about the head streak in the wild type down. Some chicks apparently lack this stripe and the trait (lack of a head streak in wild type down). Under the description of Black Breasted Red plumage: Genetics: down color Page 218, Hutt uses the reference from Bateson and Punnett from 1906 and proposed the genotype “st” - recessive lack of headstreak. On page 214 under the description for Spangling,Sp; Genetics: Patterns in Down, the recessive modifier “ma” marbling, that makes the edges of the streak irregular, and “ko” the recessive gene causing a lack of head streak. Hutt doesn’t seem confident that this gene exists on its own unless it only impacts down color and is not linked to adult color, or can be accounted for by differences between gold and silver. Seems like these are real and actual differences in the downs that are genetically controlled, but are difficult to find and replicate, because there are no detectable differences in the adults.

Kinda cool

 

[Amer]

Thanks for sharing. These are very green on the inner ring - how neat!


This note inspired me to do some digging. I found an interesting article regarding this topic:
Normal Eye Color in the Chicken

Summary: The above article describes that there are three pigments involved in creating eyecolor and Chickens: hemoglobin from the blood vessels running through the eye - the placement of these vessels and the diameter of them influence how much red you end up seeing (position of the vascular network allowing you to see red is likely genetically controlled as it did not appear to change much over time) ; yellow fat globules, containing xanthophyll pigment from the diet that will fade or intensify according to the amount of pigmented feed they receive and may also have genetic factors; and melanin, which provides a black or brown pigment, and is primarily genetically controlled. It also concludes eye color changes with age and reproduction. This would, indeed suggest that there really are only a few major genetic options: presence or absence of significant melanin (brown vs light); and presence or absence of yellow pigment (this is really only coming to play for pearl eyes and potentially gray/green since those hues are influenced by distribution of fat globules); and how visible the blood vessels are (more red or less red).

If you boil down the options, even more, that means you’re right, they really are only two major options for melanin deposition in the eyes: light or dark. But the amount of variation we see in between suggest that there are a lot of modifying genes.

Then, I went a reread what F.B. Hutt wrote on the topic in his classic “Genetics of the Fowl” Pg 489: “MacArthur (1933) added similar data for a dominant gene Br, which causes a light iris, ranging in color from yellow-orange to bay, in contrast to the brownish-blackish iris.” This quote came from a small subchapter titled “the chromosome map”. It listed the following genes to be linked to this recessive sex-linked light eyed gene Br: K (slow feathering); S (silver); Li (light down); Id ( Inhibitor of dermal melanin- you may be right about this one @Amer !); B (barred); and Ko (head streak). We just have to remember that Br is just as linked to the sex chromosome as br. It just depends on what is occurring together in the parent bird. Crossover can still occur (27% of chicks broke the link between Br and Id) and 44% and 42% between Br and S, then Br and K, respectively. Once crossover occurs, that new combination (it could be light eyes, Br, and dermal melanin id^+ that become linked instead!).

@pipdzipdnreadytogo
Thank you for prompting that dig.

Hey, half right is still something, lol. So the light eyes is sex linked recessive? Wouldn't it be br then instead of Br?

If I could describe the temper of most Bearded Belgian Bantams with a single sentence, it would be this:
BRING IT ON!

Lol, that sounds about right.

 

[KristenG]

Amer: So the light eyes is sex linked recessive? Wouldn't it be br then instead of Br?

Br is dominant red/ light eyes.
br is recessive brown eyes.

It is possible my phone auto corrected to a capital letter somewhere where it should not have been. Sorry if there was a typo.

On another note, Sometimes the notation gets confusing because some characteristics are named after the recessive gene. mutations are always named after the particular allele that causes deviation from the wild type, regardless of whether that deviation is dominant or recessive . I think we tend to assume the dominant notation is the one that usually causes the effect, it is a bias that I know I have anyway. This is why I always seems weird to me to write the same abbreviation of a recessive in capital letters even if it is to describe a different allele. Another example would be lavender:

lav is recessive lavender
Lav is dominant non- lavender.

Even though the dominant gene is not lavender, it is the alternative gene (allele) in this case, because it is not notable in any character other than normal melanin production. We are technically incorrect when we call the alternative “black”, because technically black refers to an extended black (a separate gene group) and not an alternative to lavender. The true alternative is an unaltered group of melanins.

 

[Amer]

Br is dominant red/ light eyes.
br is recessive brown eyes.

Oh, I thought you said recessive light eyes, not recessive dark eyes. That changes things completely.

 

[Amer]

I had this beautiful cockerel, the oldest: took this pic today. His eyes were lovely, though he had a little black in the beard. Sadly, I had to cull him today because he sounded congested and I have a no tolerance policy when it comes to illness. Too bad, since he was my favorite. So I guess maybe I’ll focus on beaks this year, since there are so many with beaks that are far too long. They aren’t mature yet but I’m not seeing any others with eyes quite like his.

 

[Amer]

There is this cockerel, he’s quite young:

@KristenG keep or cull? Will his breast and beard color ever match the rest of him or is it doomed to be pale forever?

 

[Amer]

Ah well, considering his other good qualities it might be worth keeping him around.

 

[KristenG]

@Amer I really liked the eyes on that male you had to cull. I completely understand about clearing out the birds with diseases though. You are right as well on many d’Anvers having beaks that are too long. Long heads, and faces seem to be pervasive in many of the Belgians for some reason. I’m glad you’re choosing to focus on it. That’s the key - sometimes you have to focus on the selection your flock presents you with.

As far as your little cockerel that you were concerned on color about, I will say that the shade of the breast in beard is always supposed to be one or two shades lighter than the gold on the back. If you have a bird that is too light with the gold on the back, it is still ideal that his breast and beard is lighter. This provides the proper contrast for the quail variety. I would certainly not cull a bird specifically because he has this proper contrast, but I might cull him for his overall gold being too light with too thick of lacing and not enough black in the hackle. I would not judge a person for holding onto Cockerel with color, such as him, because it depends on your goals. If your goal is for thicker, stouter heads, and this guy happens to have a more desirable head than anybody else - then it would make sense to keep him. It is common that the birds that are best in certain characteristics are not the best in everything. As far as color is concerned, it’s often easy to fix, relatively speaking. So if his major negative points are color, it’s not a huge concern. So in the case where you’re keeping a bird to meet a particular goal, but he has another characteristic you really don’t want to make pervasive in your flock, then you keep an additional male that is complementary and you move forward with both founding two sub-lines that you reintegrate later.

So the take away: do a pros and cons for your little cockerel as he gets bigger and see if there’s something he can contribute better than anybody else, and then make your decision. I think he’s worth hanging onto and watching.

 

[Amer]

@Amer I really liked the eyes on that male you had to cull. I completely understand about clearing out the birds with diseases though. You are right as well on many d’Anvers having beaks that are too long. Long heads, and faces seem to be pervasive in many of the Belgians for some reason. I’m glad you’re choosing to focus on it. That’s the key - sometimes you have to focus on the selection your flock presents you with.

As far as your little cockerel that you were concerned on color about, I will say that the shade of the breast in beard is always supposed to be one or two shades lighter than the gold on the back. If you have a bird that is too light with the gold on the back, it is still ideal that his breast and beard is lighter. This provides the proper contrast for the quail variety. I would certainly not cull a bird specifically because he has this proper contrast, but I might cull him for his overall gold being too light with too thick of lacing and not enough black in the hackle. I would not judge a person for holding onto Cockerel with color, such as him, because it depends on your goals. If your goal is for thicker, stouter heads, and this guy happens to have a more desirable head than anybody else - then it would make sense to keep him. It is common that the birds that are best in certain characteristics are not the best in everything. As far as color is concerned, it’s often easy to fix, relatively speaking. So if his major negative points are color, it’s not a huge concern. So in the case where you’re keeping a bird to meet a particular goal, but he has another characteristic you really don’t want to make pervasive in your flock, then you keep an additional male that is complementary and you move forward with both founding two sub-lines that you reintegrate later.

So the take away: do a pros and cons for your little cockerel as he gets bigger and see if there’s something he can contribute better than anybody else, and then make your decision. I think he’s worth hanging onto and watching.

That’s good advice, good to know.
This is the first year where I actually hatched a decent number of cockerels and can pick from them. It sounds like a good problem to have but with my hatching issues in the past I would hatch lots of pullets and few cockerels and it made it really hard to improve my birds.
Having two lines is a good idea. I don’t want to paint myself into a corner.