Incomplete dominance in snakes?

[Camille]

Hey everyone. Were doing genetics in college right now and i was woundering if theres such a thing as incomplete dominancein snakes. I know that there is co-dominance like the bloodred gene in corns and the tiger gene in retics but what about incomplete.when two dominant genes bred together mix together. say a red flower polinated with a white flower would give you pink. Co-domnant would mean both dominant genes are visible, like the rusty underbelly of a bloodred if the snake is het for blood. Just curious about it. woundering if anyone knows about any.

 

[Serpwidgets]

I think it's the other way around. That is, if you're going to split hairs by going into "codominance versus incomplete dominance," then diffusion would belong in the "incomplete dominance" category, since the phenotype is a blending of the two. If it were the other way, you would have areas of partial checkering and areas of completely normal checkering, etc.

Also, I don't think tiger retics have areas of normal patterning and areas if tiger patterning, so they would also fall into the subdivision of "incomplete dominant."

 

[paulh]

To really distinguish between a case of incomplete dominance and a case of codominance, you have to know two things. First the heterozygote must be distinguishable from both homozygotes. Second, you need to know whether a gene produces a functional product (such as an enzyme) or a nonfunctional product. If both genes produce a functional product, then it is a case of codominance. If one gene produces a functional product and the other does not, then it is a case of incomplete dominance.

Many genetics texts are out of date with their definitions.

Without the molecular data, we can't tell which is which. And we don't have the molecular data for any snake mutants. So for convenience, we lump the two cases together under the blanket term "codominance". Because it has fewer characters than "incomplete dominance", making it faster to type.

In my opinion, making a federal case out of the distinction isn't worth while, at least not from the breeder's standpoint. Because the breeding pattern is the same in both cases.

 

[Serpwidgets]

In my opinion, making a federal case out of the distinction isn't worth while, at least not from the breeder's standpoint. Because the breeding pattern is the same in both cases.

Agreed 100%. Splitting hairs or trying to split hairs in this way adds no practical value to the description of the heterozyguos phenotype. Either way, all you know is that it's somehow different than the two homozygotes.

 

[SnakeAround]

So, a 'het' showing through like with diffusion is also called co-dominance?

 

[Serpwidgets]

The idea of "hets showing through" is a psuedogenetics nonsense phrase, based on the false assumption that "het" means something is carrying a hidden mutant, and the false assumption that mutants are "supposed to be" recessive to the wild type allele.

When something is het, it is het for two different alleles at that locus. It's not possible to answer the above question in terms of the actual meaning of heterozygous.

There are three situations:
1- A mutant is recessive to its wild type allele. In this case genotype "A⁺·a^a" would look normal.
2- A mutant is codominant to its wild type allele. In this case genotype "A⁺·A^A" would look like something different than either homozygote.
3- A mutant is dominant to its wild type allele. In this case genotype "A⁺·A^A" would look like a mutant.

 

[SnakeAround]

So B says that the slight diffusing going on in a morph het for bloodred (and het for normal on the bloodred locus too), is caused by codominance of the wildtype allele and the bloodred allele on the bloodred locus? That would confirm what I was thinking, only explained better... tnx!

 

[Serpwidgets]

Yep, that's right.

 

[SnakeAround]

Okidoki! Learning moment!