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Genetics for ameraucanas

Discussion in 'Exhibition, Genetics, & Breeding to the Standard o' started by aggie2013, Oct 27, 2016.

  1. aggie2013

    aggie2013 Out Of The Brooder

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    If it helps explaining things to me. I have an extensive history in genetics for other livestock. So I understand(and love) calculating genetics. I understand how the blue and black genes relate. However, can someone explain leg color and egg shell color?
     
  2. junebuggena

    junebuggena Chicken Obsessed

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    Ameraucana have white skin and a 'slate' wash on their legs. Not really sure on the exact genetics that cause the wash, but the white skin genes are dominant over yellow. Egg color is far more simple. There are only two options for egg shell color, white and blue. Blue is dominant over white. Brown eggs have a 'coating' gene applied to the white shell. Green eggs are caused by the same brown coating, but applied on a blue shell. Coating genes are very complex and inherit independently of shell color genes. Ameraucana should lay blue eggs, the egg should be the same color inside as it is outside.
     
  3. aggie2013

    aggie2013 Out Of The Brooder

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    So it's a gene for white skin with a gene for slate acting on it?
     
  4. junebuggena

    junebuggena Chicken Obsessed

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    Correct.
     
  5. donrae

    donrae Hopelessly Addicted Premium Member

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  6. Wappoke

    Wappoke Chillin' With My Peeps

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    Ameraucana should have slate/blue/black legs. Leg color is a polygenetic trait expressed by both autosomal and sex-linked genes. The three main loci that effect shank color are the extension locus, sex-linked dermal melanin locus, and the white skin locus. There are other loci that can effect shank color but I will not discuss them because they are not a part of the Ameraucana genome.


    black - this variety has three different loci that express the black shank color- extended black (E*E/E*E), White skin W*W/W*W and sex-linked dermal melanin ID*ID/w (female) or ID*ID/ID*ID (male) The white skin and sex-linked dermal melanin express slate colored shanks and the extended black gene adds additional black pigment to the shanks resulting in black or very dark slate shanks.

    All the other varieties- the extension locus alleles vary between the varieties but none of the alleles add additional black pigment to the shank and foot. They should have slate shank color which is due to the white skin allele and the sex-linked dermal melanin allele.

    extended black allele- adds black pigment to the outer skin cells.(epidermis)

    sex-linked dermal melanin - adds black pigment to a skin layer below the outer skin layer (dermis), the pigments are black but the white skin (absence of pigment) dulls the color to a blue/slate color

    white skin- chickens can have black, yellow or white skin color. Most chickens have either white or yellow skin color. Yellow skin is due to yellow dietary pigments being deposited into the skin. White skin is due to the absence of black or yellow pigments in the skin. Black skin color is a polygenic trait. Chickens with black skin will have black shanks.

    Egg color- read the following white paper on the subject. Egg color is complicated. http://maranschickenclubusa.com/files/eggreview.pdf

    Simple explanation- blue egg color is caused by a bird having at least one blue egg shell allele and no genes for brown egg color. The blue egg locus can be occupied by two alleles- white egg shell allele or blue egg shell allele
     
    Last edited: Nov 26, 2016
    1 person likes this.
  7. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    on skin colour, black is not polygenic. It is due to the presence of the dominant Fm gene. The bird will additionally have the gene for white or yellow skin (should be white, but isn't always) but that colouring is hidden by the black skin
     
  8. Wappoke

    Wappoke Chillin' With My Peeps

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    Black skin is due to the expression of the sex-linked dermal melanin and the fibromelanotic locus. The Fm region (locus) is actually made up of more than two genes. There can be as many as 4 EDN3 genes ( the candidate gene for Fm) located in the Fm region on a chromosome. According to recent research, it takes 4 EDN3 genes located in the Fm region plus one or two dermal melanin (depending on the sex of the chicken) to produce black skin.

    Did not want to make this overly complicated but there are also other genes located in the duplicated region that most likely take part in the expression of hyperpigmentation. If this is the case then as many as 3 other genes (numbering 12- 4 alleles for each locus) may be needed to express hyperpigmentation.
     
    Last edited: Dec 6, 2016
  9. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    Reference?
     
  10. Wappoke

    Wappoke Chillin' With My Peeps

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    Shinomiya, Ai, et al. "Gene duplication of endothelin 3 is closely correlated with the hyperpigmentation of the internal organs (Fibromelanosis) in silky chickens." Genetics 190.2 (2012): 627-638.

    Dorshorst, Ben, et al. "A complex genomic rearrangement involving the endothelin 3 locus causes dermal hyperpigmentation in the chicken." PLoS Genet 7.12 (2011): e1002412.

    Dorshorst, Ben, Ron Okimoto, and Chris Ashwell. "Genomic regions associated with dermal hyperpigmentation, polydactyly and other morphological traits in the Silkie chicken." Journal of Heredity 101.3 (2010): 339-350.

    Ming, T. I. A. N., et al. "Inverted duplication including Endothelin 3 closely related to dermal hyperpigmentation in Silkie chickens." Frontiers of Agricultural Science and Engineering 1.2 (2014): 121-129.

    Ming, T. I. A. N., et al. "Genomic regions associated with the sex-linked inhibitor of dermal melanin in Silkie chicken." Frontiers of Agricultural Science and Engineering 1.3 (2015): 242-249.
     
    Last edited: Dec 6, 2016

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