Never Encourage a teacher -What I know about color genetics Lesson #2A

Discussion in 'General breed discussions & FAQ' started by mibirder, Oct 7, 2011.

  1. mibirder

    mibirder Chillin' With My Peeps

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    (Never encourage a teacher - they will never be quiet after that!) This lesson will be in two parts, Part B will follow tonight and will be as a response to this posting.

    Let’s start with a quick review from Lesson #1:
    Phenotype – What the chicken “looks” like. Just keep in mind that looks can be deceiving!
    Genotype – The specific DNA or gene “instructions” that go into the phenotype and some stuff that you might not see in appearance.
    Trait – Usually that’s one thing that you can see in the phenotype. Sometimes the trait might include several different things that happen together. Think cupcake. If a cupcake doesn’t have frosting on it, is it a cupcake or just a muffin?
    Gene – This is the DNA instructions that can create a trait. Don’t worry too much about “how it does it” just remember “what it does”. Genes are usually double dose or in a pair except some genes will be single doses in female chickens (but doubles in males)
    Dominant – These are the strongest genes and can cover up a lot of other genes in the same family of genes.
    Intermediate or Heterozygous – These are genes that will mix together if affect when in pairs – Think Red + Yellow = orange. (If one of those genes that’s single dose in females, then they can only be one or the other not mixed.)
    Recessive – These are the weaker genes and both of the pair in a double dose gene must be the same (recessive) for the trait to show. These are easily covered up by other genes in the same family of genes.
    Color Gene Families – There are four basic color gene families that go into making the whole thing you see out in the coop: 1 – Color Distribution or basic color family, 2 – Uniform color or Body color family, 3 – Color Restricting or black distribution family, 4 – Color Pattern or feather color family.

    Ready? – Before we move on to the 1st group - the Color Distribution or basic color family -there is an interesting fact to know. All of the colors of our chickens are really only “shades” of a couple of basic pigments – particularly Blacks (eumelanin) and/or Reds (phenomelanin) and variations in them. Remember, all of the colors that we can see are just made of three pigments – red, blue, yellow? Same thing except its just two pigments (There are a few more like white or Silver and Gold that we’ll cover later, but mainly its just blacks and reds. Some folks also consider white as a separate color, but in many cases, that just the absence or the basic blacks or reds.) It sort of works like an old newspaper or old TV. Remember when you got real close to the TV or newspaper you found out that a picture were just a bunch of dots. The more dots the darker the color, the less dots the lighter the color in the picture. More dots = black, less dots=gray (what we call blue). More dots =red, less dots = yellow (what we call buff).

    Ok, let’s look at that first family of genes the Color Distribution or Basic Color Family.
    These are sort of like a brand of car. There could Fords, Chevys, Chryslers, Cadillacs, etc. No matter what you do to a Ford it will never be a Caddy! The same is true for this family. There are fives different members of this family. Some, we’ll see are dominant to others – some will be recessive. They are all found in pairs in all chickens. Scientists can be kind of lazy sometimes, so they pick a short-hand or abbreviation for things – genetics is famous for this. You could pick any letter you wanted, but if you talk to somebody else using the short-hand they won’t know what you’re talking about. Because we all need to on the same page, scientists have decided to use the exact same letter when they’re talking about the same trait or gene.

    If a gene has slightly different variations of the same set of DNA instructions it can look differently in trait or appearance – think cookies. You could make chocolate chip cookies or you could make peanut butter chip cookies, or M&M. It’s all the same recipe with small variations. Or think eye color in people. The different colors are all just variations of the eye color instructions or variations of the same gene. The little variations are called alleles – different recipes for the same gene or trait.

    There are possible five alleles that make up this family. Some will be dominant to others and some will be recessive. The letter that they picked for this group is the letter ‘e’. To add a little tidbit to the short hand, Scientists use a CAPITOL letter if an allele is dominant and a lower case if recessive. So some of this group will be E and e. Wait a minute there are five so how can we use just E and e for the short hand? Well, we can/do just add in a second letter (or symbol). So for this family we have the following symbols:

    E = Extended Black (big time dominant brother and hides all the others)
    ER = Birchen (also dominant, but a little brother – it doesn’t hide E but does everybody else)
    e+ = Duckwing (a tough recessive like a tomboy sister – tough, but not as strong as her (dominat) brothersthe + is used for wild type meaning that if you found the original chicken, it would look like this one)
    eb = Brown (a little sister recessive)
    eWh = Wheaten(the most recessive – kind of like the baby sister)

    There’s always good news and bad. The bad news, is that some of these are pretty hard to tell apart for each other(until you have a good eye for it) in adult chickens. The good news is that this family also controls the color of the chick down in hatchlings. For those who hatch their own, its important to pay attention to what the hatchlings look like for this reason. In the next lesson I’ll talk about what the adults generally look like and what the chick down looks like for each of this family.

    This one was kind of long and involved. Please, let me know if this is too much info at one time or too confusing. Also, if you need clarifications please ask.
     
  2. nicalandia

    nicalandia Overrun With Chickens

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    Thanks....[​IMG]
     
  3. Illia

    Illia Crazy for Colors

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    Nicely put! [​IMG]
     
  4. nicalandia

    nicalandia Overrun With Chickens

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    Quote:can you please elavorate on this subject Complete Dominant vs Incomplete penetrance?
     
  5. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    I don't have enough time right now to go into details, but a lot of what you have written is not accurate. Check out http://kippenjungle.nl/basisEN.htm#basisEN. The definitions listed there are accurate.

    Listing the genes into families is fine, but you're mixing up gene/locus with groups of genes.

    While you cannot get change the blue gene into silver or mahogany, you CAN mix the various base alleles as they are all variations that occus at the same place (locus) on their chromosome.

    For example, it is impossible to have a bird that is Bl/S, but it is quite possible to have a bird who is E/e^b. Yes, a bird can be blue and silver, but those are separate genes that occur at different locations, not alternatives that can occur at one specific place.

    You're also mixing up colour theory. Pigment colour is subtractive, and there are many different pigments that exist. Chickens carry two of these. Light colour is additive, and while we tend to focus on specific "primary colours" (for light is it cyan, magenta yellow, whereas for pigment it is red, yellow, blue), there are an infinite number of actual colours.
     
  6. nicalandia

    nicalandia Overrun With Chickens

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    Quote:Oh wait.. let me take a closer look...[​IMG]

    Edit.
    ok you are corret Sonoran... but cut him som slack Please... I am sure he will be a good teacher around here and if he keeps his answers short I may be able to spot something that needs some help... [​IMG]
     
    Last edited: Oct 7, 2011
  7. KDailey

    KDailey Crazy Cochin Lady

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    I'll have to read over this a few times to help everything sink in but I think I'll be able to understand it.

    One request though: Could you just add on to this thread, or the original one, with the new lessons in a reply? That way we only have to keep up with one thread for the entire lesson and anybody that's just joining in can go through everything and not have to look for the rest of the lessons. [​IMG]
     
  8. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    Quote:Oh wait.. let me take a closer look...[​IMG]

    Edit.
    ok you are corret Sonoran... but cut him som slack Please... I am sure he will be a good teacher around here and if he keeps his answers short I may be able to spot something that needs some help... [​IMG]

    You're right, but I hate seeing misinformation being passed out as accurate. Also not fond of re-building something that already exists. I do like analogies.
     
  9. nicalandia

    nicalandia Overrun With Chickens

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    Quote:oh how I wish you were here as often(I concider you as one of my mentors since my early days at the coop and you are still are)

    some times I have to just agree to disagree with some of our friends here...

    Quote:Quote:
     
  10. tinychicky

    tinychicky Chillin' With My Peeps

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    okay so why do i have a white, gray and fawn pullet out of a black silkie/black mottle d'uccle hen X bb red oegb/ (black mottle d'uccle/black cochin) rooster crossed with a pure wheaten ameraucana roo (or possibly a white barnyard mutt with the same father as the hen and a mother who's a black silkie/black cochin/black mottled d'uccle/black rosecomb/ white cornish)? it would be awsome if youcould explain that too me. thanks [​IMG]
     

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