the codominant mode of inheritance has been used for so long it is now part of our everyday "boa morph language."

The problem lays in the fact in a litter of potentially homozygous dominant and heterozygous hypos, there is phenotypic cline from "barely a hypo" to nearly blackless, fleckless animals (which many times prove out to be supers, or homozygous dominant hypos). There is such a degree in variation we want the mode of inheritance to be more than complete dominance. Even within known heterozygous hypos there is a high degree of variation.

In classical codominance, both alleles are generally expressed equally to yield a phenotype indicative of both allles. At the organismal level, this may result in heterozygotes having an intermediate phenotype (i.e. somewhere between a homozygote dominant and a normal).

In Rich's (and others) article on the Salmon hypo in the Journal of Heredity states the mode of inheritance of this character as being incomplete dominance, as the hypo mutation (or allele) incompletely dominates the normaly functioning allele yielding intermediate phenotypes.

If we were able to definitively decifer between a homo and hetero hypo from a litter, we would not be having this discussion. We would just say it is either codiminant or incomplete.

The whole thing is convoluted, but I agree, the safest thing we can say is this particular trait results from complete dominance.
-----
Ron Michelotti

Class Reptilia
www.classreptilia.com

[ Show Entire Thread ]