Quote:
Originally Posted by crotalusadamanteus
You might have me on the Salmon gene stuff. I have read pretty good arguments to back that it is dominant, but have read just as much to contradict that.
Example. If you breed a wild type with a Salmon.
If it was a dominant trait, it would produce a litter of salmons 100%, just as the wild type gene acts dominant when bred to an albino. You get all wildtypes. Granted, they are all het albino, but the dom gene is expressing itself as normal.
But you don't get all salmons, you get some of each, normals, and hypos. This supports the co-dom theory. Which I still believe it to be due to the way it acts.
Getting interesting though. I could talk this stuff for ever. LOL
But my friend, (lurking over my shoulder right now) still aint convinced. LOL
Ciao,
Rick
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Two alleles can be paired in one of three ways. Let's use the Salmon mutant (S<sup>S</sup>) and its wild-type counterpart (S<sup>+</sup>) for example. The three possible genotypes at the salmon locus are:
S<sup>+</sup>·S<sup>+</sup> Homozygous Wild-type
S<sup>S</sup>·S<sup>+</sup> Heterozygous Wild-type and Salmon
S<sup>S</sup>·S<sup>S</sup> Homozygous Salmon
If salmon is recessive to wild-type:
S<sup>+</sup>·S<sup>+</sup> = Normal phenotype
S<sup>S</sup>·S<sup>+</sup> = Normal phenotype
S<sup>S</sup>·S<sup>S</sup> = Salmon phenotype
If salmon is dominant to wild-type:
S<sup>+</sup>·S<sup>+</sup> = Normal phenotype
S<sup>S</sup>·S<sup>+</sup> = Salmon phenotype
S<sup>S</sup>·S<sup>S</sup> = Salmon phenotype
If salmon is codominant to wild-type:
S<sup>+</sup>·S<sup>+</sup> = Normal phenotype
S<sup>S</sup>·S<sup>+</sup> = Intermediate phenotype
S<sup>S</sup>·S<sup>S</sup> = Salmon phenotype
OR, as is done in some cases:
S<sup>+</sup>·S<sup>+</sup> = Normal phenotype
S<sup>S</sup>·S<sup>+</sup> = Salmon phenotype
S<sup>S</sup>·S<sup>S</sup> = "Super salmon" phenotype
The simplest question to answer is this:
Can you tell by looking at a snake if it is homozygous or heterozygous Salmon? If yes, the salmon mutant is codominant to wild-type, otherwise it is dominant to wild-type.
The other way to put it is this:
How many phenotypes are there? If there are two phenotypes, the relationship is dominant/recessive. If there are three phenotypes, the relationship is codominant.