What Really Is Normal?

[Serpent_Nirvana]

Normal IS recessive, or it can be.

"Normal" is, as has already been stated, nothing more than our term for what the majority of ball pythons look like when not expressing any mutant genes. In ball python lingo, "normal" is a phenotype -- a physical appearance -- that we use to mean that the animal is not expressing any mutant color or pattern genes.

When referring to specific genes (such as spider, albino, etc.) the "normal" gene on any given gene locus is more properly referred to as the "wild-type form." At each gene locus (again, such as albino, spider, etc.), there are two different alleles, one from mom and one from dad. An animal that is heterozygous ("het") at any given locus has a different allele from each parent at that locus. So, a het albino has one "albino" (mutated) allele and one wild-type (non-mutated) allele at the "albino locus."

Because on this specific locus (albino), wild-type is dominant to mutated, an animal with only one wild-type gene (a "het albino") will look "normal" (have a normal phenotype); you only get an albino-looking animal when you have NO wild-type alleles on the albino locus.

Pinstripe, however, is dominant to wild-type. This means that wild-type is recessive to pinstripe. If you have only one pinstripe gene, the animal will look like a pinstripe. If you have two pinstripe genes, (we think) the animal will still look like a pinstripe. The majority of pinstripes are heterozygous pinstripe, and also, technically, "het for normal (wild-type)."

Spider is also dominant to normal; if you have one copy of the "spider" gene, the animal WILL look like a spider. There is no such thing as a normal het for spider because if the animal had one copy of the spider gene, it would look like a spider, not a normal. Ditto for pinstripe, lesser, cinnamon, etc., etc..

As to WHY, on a molecular level, the spider and pinstripe genes are dominant to normal ... I have no idea. I don't think anybody knows, because this stuff has not yet been studied in snakes. (And if you do know, please tell us! )

I can tell you that, oftentimes, when a mutant gene is recessive to wild-type, that means that the animal can get by with only one copy of the wild-type gene producing protein. So for albino, you only need one copy of the wild-type gene to make enough enzyme to make enough melanin for the animal to look normal. You only see the albino form when there is no enzyme at all making melanin.

I hope that didn't confuse anyone more ... And for the other genetics geeks on here, YES, I oversimplified it. Apologies. (Yes I could talk about this crap all day long, thankyouverymuch ... )