I read some of the information on the Marans thread and would like to post this to answer some questions.
Genetics 101
This post deals with white to black shank color in chickens. Marans should carry the gene for white skin and therefore have white skin.
This post only deals with black copper marans. Please do not ask questions about other breeds or varieties.
1. The shank has two layers of skin that deals with shank color.
2. The top layer of skin is called the epidermis and is made up of the scales and the area between the scales.
3. Just under the scales (epidermis) is a layer of skin called the dermis.
4. Certain genes add black pigment to the epidermis and other genes add black pigment to the dermis.
5. The extended black gene (E) is an allele to birchen (E^R) and wheaten e^WH. The extended black gene will add eumelanin (black pigment) to the epidermis or scales. Research indicates that birchen will add some black pigment to the epidemis- usually it does not add black pigment to the epidermis. The birchen birds I have been working with express more than a small amount of black in the epidermis. This could be the case for your black coppers.
If your bird carries an extend black allele, this allele (E) will add black pigment to the scales and very little to none in the tissue under the epidermis. You will be able to see pigment in the scales and not the dermis under the scales.
Normally the birchen allele ( the allele in black copper marans) does not add black pigment to the scales but it can add small amounts.
A bird could have the black copper phenotype ( what the bird looks like) and carry one extended black allele and a birchen allele. This is what I call a pseudo-birchen or false birchen. In this case the bird will have black pigment in the scales because the bird carries an extended black allele.
If a marans breeder is having problems with solid black females being produced from crossings, this is an indicator that the extended black allele is found in the breeders.
The wheaten allele inhibits the addition of black pigment to the epidemis ( scales ) of the chicken. Wheaten birds may show some brown pigment in the scales.
6. Another gene called dermal melanin will add black pigment to the dermis. Dermal melanin is a recessive sex-linked gene. The allele to dermal melanin is dermal melanin inhibitor. Males can have two dermal melanin alleles or a dermal melanin inhibitor allele and a dermal melanin allele or two dermal melanin inhibitor alleles.
The color in the male shank dermis depends on the dermal melanin gene.
two dermal melanin = dark blue shanks
dermal melanin inhibitor + dermal melanin = white or very light gray/ light blue shanks
dermal melanin inhibitor + dermal melanin inhibitor= white shanks
Females can only have one allele; they carry either dermal melanin or dermal melanin inhibitor.
dermal melanin = blue shanks
dermal melanin inhibitor= white shanks
7. Epidermal scales pigmented with black are black or dark slate ; dermal tissues pigmented with black are blue or dark blue.
Tim
Genetics 101
This post deals with white to black shank color in chickens. Marans should carry the gene for white skin and therefore have white skin.
This post only deals with black copper marans. Please do not ask questions about other breeds or varieties.
1. The shank has two layers of skin that deals with shank color.
2. The top layer of skin is called the epidermis and is made up of the scales and the area between the scales.
3. Just under the scales (epidermis) is a layer of skin called the dermis.
4. Certain genes add black pigment to the epidermis and other genes add black pigment to the dermis.
5. The extended black gene (E) is an allele to birchen (E^R) and wheaten e^WH. The extended black gene will add eumelanin (black pigment) to the epidermis or scales. Research indicates that birchen will add some black pigment to the epidemis- usually it does not add black pigment to the epidermis. The birchen birds I have been working with express more than a small amount of black in the epidermis. This could be the case for your black coppers.
If your bird carries an extend black allele, this allele (E) will add black pigment to the scales and very little to none in the tissue under the epidermis. You will be able to see pigment in the scales and not the dermis under the scales.
Normally the birchen allele ( the allele in black copper marans) does not add black pigment to the scales but it can add small amounts.
A bird could have the black copper phenotype ( what the bird looks like) and carry one extended black allele and a birchen allele. This is what I call a pseudo-birchen or false birchen. In this case the bird will have black pigment in the scales because the bird carries an extended black allele.
If a marans breeder is having problems with solid black females being produced from crossings, this is an indicator that the extended black allele is found in the breeders.
The wheaten allele inhibits the addition of black pigment to the epidemis ( scales ) of the chicken. Wheaten birds may show some brown pigment in the scales.
6. Another gene called dermal melanin will add black pigment to the dermis. Dermal melanin is a recessive sex-linked gene. The allele to dermal melanin is dermal melanin inhibitor. Males can have two dermal melanin alleles or a dermal melanin inhibitor allele and a dermal melanin allele or two dermal melanin inhibitor alleles.
The color in the male shank dermis depends on the dermal melanin gene.
two dermal melanin = dark blue shanks
dermal melanin inhibitor + dermal melanin = white or very light gray/ light blue shanks
dermal melanin inhibitor + dermal melanin inhibitor= white shanks
Females can only have one allele; they carry either dermal melanin or dermal melanin inhibitor.
dermal melanin = blue shanks
dermal melanin inhibitor= white shanks
7. Epidermal scales pigmented with black are black or dark slate ; dermal tissues pigmented with black are blue or dark blue.
Tim
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