Look, you are a smart person, and you have a good idea of what you get when you cross certain morphs of snakes, but you keep confusing genotype with phenotype. They are related but they are not the same.



Phenotype is what the you see expressed; genotype is the genes themselves. Albinism is a recessive trait that results from an absence of pigment formation. You do not use it directly when doing a cross. Lets take a basic example. In genetics labs, students work with fruit flies. There are as far as color goes two types, wild and albino. The wild type is generally shown as “W” with the albino form shown as “w”. When you do the square for a cross between a homo wild with an albino it is shown as "WW x ww" and the offspring are shown as "Ww".



If Black Rat Snakes had just one gene that controlled color and the snake could be the wild type and the albino type, then you would show the cross as I did above. There would be only one letter used, and the small form of the letter would be used to express the albino form of the gene. An albino would be indicated by having the wild trait expressed as two small letters.



Since a Black Rat Snake has multiple genes for color, you have to show each gene involved as separate when you do your cross. Let us say that a Black Rat has genes for black, brown and white. Let use then say that we are crossing it with an albino form of the snake. The cross would be done something like this: “BB,NN,WW x bb,nn,ww” where "B" stands for black, "N" stands for brown and "W" stands for white. Note that the albino form is shown with all small letters for the genes involved. The resulting offspring would be shown as "Bb,Nn,Ww" and it would tell us that only the wild types were expressed in the offspring. Plese also note that the albino snake could only be one that is "bb,nn,ww". If it were something like "bb,nn,Ww"' it may look a lot like an albino, but it would not be a "true" albino.



At this point, I hope that we all agree that there is more then one gene involved in the albino and leucistic forms of black rat snakes. After all, they are phenotypes and not genotypes. You would also never show a cross of these snakes as "AA,ll x aa,LL" because you would be showing the phenotypes and not the genotypes that produce such snakes.

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