Id Light foot color. Dominant. Inhibits dermal melanin. Reported to have little influence on shank/foot color in birds with dark shanks due to E/E
idc Recessive. This gene allows beak and sometimes plumage pigmentation in dominant white homozygotes.
ida Allows green spots on shanks - this gene is not widely accepted and the effect of this gene may be due to the interaction of modifiers not allelic to this locus.
idM Massachusetts mutation. Recessive. Unlike other alleles that belong to this locus, dermal melanin is present in shanks of day-old chicks. Other alleles take more time to express. The darkest shanks are produced in conjunction with E and i+. The combination of idM, E and I produces a pale blue or green color by about three months of age.
id+ Wild-type dermal melanin. Lack of dermal melanin inhibitors.
Here's a BYC thread, that I haven't read <--(POETRY) as of yet, but now that you are asking I'll dig up some good stuff, and revisit our pending question about ear lobes. Dropped the ball on checking all except one book I have that didn't have anything ear lobe-y.
Here's a good one! https://scratchcradle.wordpress.com/2012/09/02/gms10-skin-and-shank-color/
diagram is from that site:
Found this -- because I knew I had seen shanks on Henk's chicken calculator -- but there are several versions of the calculator -- this shows shank and some variable genes so you can 'play around' with changing the colors.
Regarding crossing Leghorns with a variety of red earlobe breeds the author writes "Four grades were recognized; namely, white, predominately white, predominately red, and red. It is realized that there is some experimental error in using so crude a system of classification, but since it was the more accurately defined first and last grades that were of primary interest it seemed to satisfy the needs of the experiment at hand. The intermediate grades were not cases of blending of the red and white but the mingling of the two in varying proportions. The variations are probably quantitative ones depending upon the amount of white tissue deposited and the relative amounts of white and red are determined by the proportion of the surface of the earlobe covered by the white".
F1 cross results
Thanks Brahma Chicken5000.
Does it seem like some genes are easy and direct -- and then in some of the traits chickens have there is a lot under the covers. That scratch cradle article on shanks said that what they thought was once dominant is now considered recessive (or was it vice versa)---
One thing is for certain -- a lot of people who focus on just one thing (like bigger eggs or something) have the ability to mess up a rare breed (like Cream Legbar ) When they don't know what they are doing. Somehow someone in UK put recessive white into cLs-- and that caught on as a 'fad' IMO -- trouble is it took away the autosexing of the white ones, and the whole breed was developed for autosexing.
Seems like the best thing to do would be take a slow approach to select from one's own flock for the desired traits and outcross only when you know what you are doing -- because Murphy's Law says you'd introduce genetics that if looked at squarely would be considered undesirable.
So perhaps definitive stuff on earlobe color has yet to be discovered.
If I don't get back here....It's that happy time of year again in time to say it... Merry Christmas to all...and to all a good night. (And a Happy New Year)