The White & Yellow (W&Y) gene complex is indeed a very interesting project to work with. Is is a relatively new morph and many breeders have their own theories regarding its inheritance and expression. I have observed many variability in the expression of the W&Y quality from my past breeding season, which was very fascinating for me.
My W&Y TUG Sunglow and W&Y Bell Enigma (both low expression W&Y) gave me offspring that covered the whole spectrum of low to high W&Y expression.
I was in consultation with a few W&Y breeders, including Leekura Anne-Gaëlle from France, and most of them support the "graded expression" of W&Y - a classification system is yet to be developed in order to shed more light and clarity on this topic. This reminded me of the Piebald morph in ball pythons... Although it is a recessive trait and genotype-stable, its phenotype is randomly graded from low to high expression. One could only postulate, and this is purely my opinion, that the W&Y gene might find itself in a similar situation: Dominant inheritance with randomly graded expression of W&Y traits. There are a few polygenetic traits that tend to mask the W&Y to a certain degree, so there might be some sort of interaction.I do believe that line breeding will play a role in "fine tuning" the morph's general appearance. All of us that is working with the W&Y morph has some homework to do, and hopefully in the near future we will gain more insight in this spectacular morph.
With regards to your W&Y Murphy's Patternless, please do post some updated pictures as it develops. Think it would be an interesting thing to follow and very educational for all.
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