Thanks Tom. I learn something new every day.
So presumably the bantams are eb blacks (blues & lavenders)?
From recent reading I'm starting to think there are more to dark shanks than I'd previously thought.
For anyone who might find the info useful, & doesn't already know, the predictability of skin & shank colour can be generalised:
In the case of black based colours, alleles at the e-locus affect the outer layer of skin (the epidermis).
Most yellow (or even white) legged blacks (blues or lavenders) are what is known as eb blacks rather than extended black.
Birds with black or blue/dark slate legs tend to be on extended black.
Extended black is dominant to eb.
A domonant sex linked gene called inhibitor of dermal melanin (Id) inhibits the dark pigment from the inner layer of skin (the dermis).
Without Id the legs will be bluish or willow depending upon whether the bird has white or yellow skin.
It is necessary to have eb or one of the alleles recessive to extended black & also to have Id for a birds legs to be able to be white or yellow.
When the black pigment is absent from both layers of the shanks another set of genes can determine whether the skin colour will be white or yellow.
White skin (W+) is dominant to not white skin (w). The gene w allows carotenoids (such as in green things or corn) to make skin yellow. Yellow skin, being recessive, when bred to yellow skin ought to give all yellow skinned offspring. All things being equal, white skin bred to white skin can give around 25% yellow skinned offspring but only if both parents are carrying a gene for non white skin.
So presumably the bantams are eb blacks (blues & lavenders)?
From recent reading I'm starting to think there are more to dark shanks than I'd previously thought.
For anyone who might find the info useful, & doesn't already know, the predictability of skin & shank colour can be generalised:
In the case of black based colours, alleles at the e-locus affect the outer layer of skin (the epidermis).
Most yellow (or even white) legged blacks (blues or lavenders) are what is known as eb blacks rather than extended black.
Birds with black or blue/dark slate legs tend to be on extended black.
Extended black is dominant to eb.
A domonant sex linked gene called inhibitor of dermal melanin (Id) inhibits the dark pigment from the inner layer of skin (the dermis).
Without Id the legs will be bluish or willow depending upon whether the bird has white or yellow skin.
It is necessary to have eb or one of the alleles recessive to extended black & also to have Id for a birds legs to be able to be white or yellow.
When the black pigment is absent from both layers of the shanks another set of genes can determine whether the skin colour will be white or yellow.
White skin (W+) is dominant to not white skin (w). The gene w allows carotenoids (such as in green things or corn) to make skin yellow. Yellow skin, being recessive, when bred to yellow skin ought to give all yellow skinned offspring. All things being equal, white skin bred to white skin can give around 25% yellow skinned offspring but only if both parents are carrying a gene for non white skin.
