Genetics....

[paulh]

So have been doing a lot of reading and studying on genetics due to the Dom, Co-Dom, Recessive terms thrown around with the occasional Allele and Locus thrown in there.. So in trying to further my understanding of what I am seeing in breeding I am starting to believe there are some truths misrepresented. The first one would be our labeling of dominant genes. Dominant gene would mean that anything on the same locus and the corresponding allele would be overridden by the dominant gene. We have called Spider and Pinstripe dominant genes, when in reality they may be dominant to some alleles but they are in fact incomplete dominant, hence the spinner that comes from the mixing of the two. Also, Co-Dominance means that there will be evidence of the individual alleles present in the resulted phenotype, for example if Mojave and Cinnamon were true Co-Dom you would see part Mojave and part cinnamon on the same snake (which from study sounds a lot like paradox but I am not even going there), instead we once again see incomplete dominance because the result in most of our breeding shows a mixing of different alleles that are not distinctive of the originals. I am not saying I have this 100% down, because I surely don't but I think based on what I read you could refer to Mojave as an incomplete dominant gene with most other allelic combinations and co-dom is mostly in reference to genes like Spider/pinstripe, but in truth these alleles lie on different parts of the genes or possibly another place on the DNA strand all together... and fire away and bash me!!! lol

You are correct in writing that herpers misrepresent some truths. That is why I prefer standard genetics definitions to the herper versions. You might like to look at the Genetics Home Reference -- http://ghr.nlm.nih.gov/handbook. It's free.

The dominant/codominant/recessive classification results from a comparison. For example, both the mojave gene and the lesser gene are codominant (for this discussion a synonym of incomplete dominant) to the corresponding normal gene. However, the lesser gene is dominant to the mojave gene. Because both the super lesser and the het lesser/mojave snakes are blue-eyed white, while the super mojave is nearly a blue-eyed white but has some pigment on the top of the head and neck. The classification is different because the comparison is to different gene. I could point to several examples (not in snakes, yet) where one gene is dominant to a second gene, codominant to a third, and recessive to a fourth.

The comparison can be either explicit or implied. "The lesser gene is dominant to the mojave gene" is an explicit comparison. "The lesser gene is a codominant mutant gene" is an implied comparison. And when the comparison is implied, the assumption is always that the comparison is with the corresponding normal gene.