Posted by:
Greg Graziani
at Wed Sep 20 11:37:01 2006 [ Email Message ] [ Show All Posts by Greg Graziani ]
Not to make things confusing but there is more going on here than codominance. The Lesser Platinum along with a number of other mutations in likely to be a null mutation, haploinsufficient or hypermorphic mutation not codominant. If that is the case you are correct. You have the possibility of producing Super Pastels, Super Pastel Lessers and double homozygous Super Pastel-Super Lessers AKA Blue Eyed Leucistics. Because your parental stock were both Super Pastels you know that all of the offspring are Super Pastels, but due to the Super Lesser wiping out all of the pigment you are left with a phenotype of an all white snake. Now if your breeding pair was a Pastel Lesser and a Super Pastel Lesser you would not be able to visually distinguish the difference between Leucistics that are Super Pastels and the Leucistics that are Pastels.
Most breeders/hobbiests are unaware of any other forms of domianace besides dominance and codominance here are a few other possibilities.
Null Allele (Null Mutation)- A nonexpressed allele; a mutation that completely eliminates function of a gene. Mutation that abolish the function of a protein encoded by the wild type allele. Such mutations either prevent synthesis of the protein or promote synthesis of the protein incapable of carrying out any function.
Haploinsufficiency- A rare form of dominance in which an individual heterozygous for a wild type allele and a null allele shows an abnormal phenotype because the level of gene activity is not enough to produce a normal phenotype.
Hypermorphic Mutation- Produces an allele generating either more protein than the wild-type allele or the same amount of a more efficient protein. If excess protein activity alters phenotype, the hypermorphic allele is dominant.
To my knowledge the above mutations can only be identified by chemical testing, but what is happening with a number of ball python mutations dose not phenotypically fit the definition of codominance.
Hope this helps,
Greg
Graziani Reptiles
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RE: mind-bender genetics question... - Greg Graziani, Wed Sep 20 11:37:01 2006