This was posted in the ball python forum by Paul Hollander last week. While it uses pastel ball pythons as an example, I still think it can help a lot of people out. Paul, I hope you don't mind me posting this.

Also, April, hypos are dominant because you can't distinguish a "super" hypo from a "non-super hypo". This is because when you pair a hypo allele with a normal allele, the hypo allele is dominant to the normal one and fully expresses itself. An example of a codominant gene is the motley. When the motley gene is paired with a normal allele, it partially expresses itself and the normal allele partially expresses itself. They are codominant, rather than one being dominant to the other. Now, when you pair two motley alleles together, you get the purple patternless (I know not proven yet, but come on). In this case the motley allele is able to fully express itself without the normal allele trying to bully its way in. Hope this helps April.

Now for Paul's post regarding pastel ball pythons:

""Super" has absolutely no standing in standard genetics terminology. In herper slang, a super is an animal that is, in standard genetics terms, homozygous for (has a pair of) either a dominant or a codominant mutant gene. This useage got started from the super tiger reticulated python and has been extended to animals that are homozygous for a dominant mutant gene like salmon in boa constrictors.

Animals are NOT dominant or codominant. Animals are (homozygous or heterozygous) for a (dominant or codominant or recessive) mutant gene. A mutant gene is dominant or codominant or recessive to its normal allele.

"Partial dominant" is a full synonym for "incomplete dominant". For practical purposes, "incomplete dominant" and "codominant" are synonyms. "Partial dominant", "incomplete dominant", and "codominant" are NOT synonyms for "heterozygous" except in herper slang, which has no standing in standard genetics terminology.

If a ball python has two copies of the pastel mutant gene, it is homozygous pastel. If a snake has a pastel mutant gene paired with a normal gene, it is heterozygous pastel. And pastel is a codominant mutant gene because a homozygous pastel can be distinguished from a heterozygous pastel just by looking at them.

In other words, a ball python with two copies of the pastel mutant gene is not a "dominant pastel". It is a homozygous pastel ball python. A snake with a pastel mutant gene paired with a normal gene is not a "codominant pastel". It is heterozygous pastel. And pastel is always codominant to its normal allele. It does not matter whether a snake has two copies of the pastel mutant or a pastel mutant gene paired with a normal gene; pastel is a codominant mutant, period.

Clear as mud?

Paul Hollander"



Hope this all clears some things up. Rainshadow, if I screwed any of this up, please correct me.

Thanks,
Matt Crabe

[ Show Entire Thread ]