https://poultrykeeper.com/poultry-breeding/the-other-type-of-gold-red/
Mahogany does have a restricting effect on black, but not in the same way that columbian does. Mahogany restricts black through the hackle and wing, it has no effect on black chests.
I posted that mahogany was columbian-like; I did not post that it was expressed in the exact same way. Dark brown is another columbian-like restrictor. This is a term used in research papers to refer to black restrictors as a whole. See the following quotes from Smyths paper.
"As I visualize the situation, the genetic determination of primary plumage pattern revolves around the genotype at the E--locus and its modification by other genes with primary pattern effects. This idea is presented diagrammatically in Figure I. Each of the E--alleles determines a specific primary pattern, varying from the extreme black distribution of the E--allele to the greatly reduced amount present in the wheaten (eWh and eY) females, With the appropriate modifying genes the eumelanin distribution associated with any of the E--alleles may be moved to the extremes, solid black or essentially non-black Columbian-like (as in the clear Buffs)."
"Several genes have been isolated that further restrict the black distribution associated with the unmodified E--alleles, primarily in the direction of a Columbian-like pattern. These include Columbian (Co),mahogany (Mh) , dark brown (Db)and dilute (Di). In addition there appears to be unidentified modifying genes such as those proposed by Somes and Smyth (1966) which tend to behave as a polygenic complex. Various genotypic combinations of the above can account for the many modified phenotypes ranging from a wild type male with slight red tipping on its black breast to a phenotypically non-black Buff Orpington."
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Poultry keeper is not a scientific journal. Nowhere in the internet article does Grant present data that would support the statement. I am surprised Grant would present an article that had incorrect information. He discusses the Ap gene which can be found in the chicken genome but
the gene has nothing to do with color in a chicken. The Ap gene expression is referred to as apterylosis- featherless chickens. This is a dominant gene that produces chickens that have varying degrees of nakedness. Read the information in the book below.
http://chla.library.cornell.edu/cgi...dno=2837819;didno=2837819;view=image;seq=0130
Grant did not read the work by Brumbaugh and Hollander or the work by Smyth. All three of the authors have been published numerous times in scientific journals.
So you are saying the conclusion drawn from the data collected by Smyth, Brumbaugh and Hollander is incorrect. I do not understand how you can dismiss the findings of these researchers. The work by these individuals is used by other researchers to support their findings . Smyth, Brumbaugh and Hollander have published many papers on genetics and are referenced many times by other scientists.
The file below is the paper by Brumbaugh and Hollander
http://chickencolours.com/Genetics of Buff Brum&Holl.pdf
I have also read Brian Reeder's (Reeder was mentioned in the online article) paper on the subject of autosomal pheomelanin. His paper was never published in a peer-reviewed scientific journal. If he had tried to publish the article, it would have been rejected-
he used a published genotype to represent the autosomal pheomelanin. From what I can gather, he did not do a literature search.
You can believe what you want to believe but I can not understand how you can dismiss published research.
