Good thoughts and great post.



I think what is clear is that hypomelanism is a recessive mutation. But, genes rarely if ever work in isolation from the influence of other genes in the genome. This was recognized by one of the fathers of genetics (Sewall Wright), he said that it was stupid to "treat genes as if they had constant effects, favorable or unfavorable, irrespective of the rest of the genome".



In genetics we refer this as epistasis, which is just genetic jargon for genes (or alleles) modifying how other genes (or alleles) are expressed. I think this is what is responsible for the variation we see in the degree of hypomelanism between individuals. Many of the other genes in an individual can influence how much melanin is present in the skin. For example, if you have some individuals that have a collection of genes which lead to "clean and light" animals that are not technically hypo (because they have fully functioning genes), it makes sense that if crossed into a hypo line you would end up with really light and clean hypos. This is something we know and do all the time in selective breeding.



So, while hypomelanism a recessive mutation it is definitely the case that the degree of pigmentation and the pattern it takes in the skin are polymorphic.



Vinny
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“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone on cycling according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” -C. Darwin, 1859



Natural Selection Reptiles

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