>Me and a friend of mine had a disagreement about genetics yesterday. So I would much appreciate anything anybody could contribute to find the correct answer. And if it wouldn't be too much trouble, please mention any education recieved on the subject. For example I know some people have taken college classes on specifically genetics. Just for credibility purposes when me and him look over the responses.



My qualifications: I took a college course in genetics and worked five years as a full time technician in the Iowa State University Genetics Laboratory.



>My Arguement was that a hypo that is not a homozygous (super) hypo is technically a Heterozygous hypo. The reason being that it carries 2 different alleles from 2 different genotypes of parents.



This is 100% correct. It is the standard genetics definition. The appearance of an animal has nothing to do with whether it is heterozygous or homozygous. Also see the definition at http://dictionary.reference.com.



>My friend's side of the arguement was that the term heterozygous means that a normal looking snake carries a recessive gene. The gene just does not show in the snakes phenotype. And also argueing my point that F1 hypos are not considered a heterozygous hypo because heterozygous has to be referring to a recessive trait.



Many herpers believe your friend's statement. It gained currency because for many years only recessive mutants were known in snakes.



>...it does not matter if a trait is recessive or not, it simply refers to the alleles being different, which can be caused from a co-dominant gene, dominant gene, or recessive.



100% correct as far as you go. As you write, a heterozygous gene pair can be a normal gene and a mutant gene, and the mutant can be dominant, codominant or recessive to the normal gene. A heterozygous gene pair can contain two different mutant genes. For example, it seems likely that a paradigm boa has a gene pair containing a Sharp albino mutant gene and a boawoman caramel mutant gene. The two mutants are different, which makes the snake heterozygous.



>Another thing I would like to mention, although me and him did not get this far into it yesterday, but I know his thoughts on it. Lets make it clear that co-dominant and dominant have NOTHING to do with being a homozygous (super) animal. I think that is a huge misconception in breeding boas that a lot of people do not know the truth.



Sadly, true.



>Hypos are dominant. I hear people refer to them as co-dom because if bred to a normal boa, the litter would be 50%/50%. This is the wrong way of thinking. They are dominant because the phenotype of a "het" hypo looks almost identical to the phenotype of a "homozygous" hypo. If a "het" hypo was bred to a "het" hypo, the babies would be approximately 50% het hypos, 25% normals, and 25% "homozygous/super" hypos. It works on the punnet square the same as a recessive gene would. We can make an educated guess on how to distinguish which is which between "het" hypos and "homozygous", but until its proven through breeding, it is unknown for sure.



True.



>This is different from the Motley gene. The motley gene is co-dominant. This is because if a "het" motley was bred to another "het" motley, the phenotype of the homozygous form is jet black with black eyes, looking completely different than its sibling "het" motley. And breeding a "het" motley to a normal wild type boa, would produce 50% "het" motleys, and 50% normal boas.



I'm not up on motleys, but if the phenotypes are as described here, this is all true.



>The bottom line is these 3 points.....

>

>- Heterozygous does NOT mean carrying a ressive gene, it means carrying 2 different alleles



I'd prefer to write "having" rather than "carrying", which has connotations of not showing the effect of the gene. Otherwise, right.



>- F1 Hypos are technically considered "heterozygous" hypos



Ideally both parents in the P generation are homozygous for different allelels. If a homozygous hypo is mated to a homozygous normal, then all the F1 babies are heterozygous hypo. If the hypo in the P generation is heterozygous, the hypo F1s are heterozygous hypos and the normal F1s are homozygous normal.



>- Hypos are considered a dominant gene, while motleys are co-dominant.



This seems the best explanation today. The salmon mutant gene (AKA hypo) was originally described as an incomplete dominant (= codominant) mutant gene. After many more breedings than in the original paper, we now know that many homozygous hypos cannot be distinguished from heterozygous hypos. The change in interpretation comes from more information than was originally available.



>Can I please have the opinions/support of everybody else who knows anything about genetics and how they work? If I am wrong about all of this, please say so, but I think I've just about hit the nail on the head for most of it.



Yes, you have.



>Also, a question for my own knowledge, generation hypos... how does it work? I am under the assumption that F1 x F1 = F2, F2 x F2 = F3, F3 x F3 = F4, and so on. is that correct? And what would be produced by breeding F4 to normal wild type? Im under the assumption of F1s would be the result. Any knowledge to this would be greatly appreciated.



The F1, F2, etc. system is not much use outside a formal genetics cross designed to figure out whether a mutant gene is dominant or recessive to the normal allele. Your F4 could be either a heterozygous hypo or a homozygous hypo, and is better described that way. With the possible addition of a pedigree.



Cheers,

Paul Hollander

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