Genetics ?? Hypo gene specifically

OK, maybe I can get some help with an ongoing debate here.
We all know that the Hypo/Salmon gene in BCI is a co-dominant gene. Correct?
Heres the debate..........I am currently breeding My 8ft Albino female (Kahl '99) to a male Hypo het for albino, (or sunglow if you choose).
I say that there will be +/-half a litter of normals het albino, and +/-half a litter of albinos. Then comes the co-dom Hypo gene.
It will distribute randomly through out the litter correct? Their is no way to tell which offspring will get that hypo gene. So you could get all yer normals being DH Salmons, or all your albinos being sunglow, or any combination in between. It's not a guaranteed ratio.
I am being told it "Will be 25% of each....Norm hets, salmon hets, albinos, and sunglows" by a friend of mine. I disagree as you can see.

It goes further yet................Same thing for the Super Salmons. Some say two co-dom genes will make a Dom gene. Again I say "random distribution" You may or may not get Supers from the two salmons. My friend believes they will all be Supers.

Don't get me wrong. My friend is not a breeder, or even a keeper at the moment. He's just sorta smart in the science department, and I talked genes in Boas to him one day and created a monster. He even has me doubting all that I have learned about this stuff.

It's time to settle it. I know there are breeders out there who have gone through these experiences, and am hoping they will give their opines.
Who knows, Maybe I got it all wrong. I doubt it, but maybe.


Ciao,
Rick

I just started working with Boa Morphs last year, and so I do not have the experience that others do however I just thought that I would come to your friends defense a bit.

I believe that your friend is actually correct, sort of. I haven't done the math, but he is probably talking about if you did a Pundit Square. It is by no means an exact forecast, but it gives you a general idea of what to expect.

I don't breed boas, but if the gene for hypomelanistic is co-dominant, and you breed an albino to a hypo heterozygous for albino, you would theoretically expect:
25% Normal heterozygous for albino
25% Hypomelanistic heterozygous for albino
25% Hypomelanistic albino (sunglow?)
25% Albino
So if that's what your friend meant, I guess I'd agree with him there.

As far as the "super" hypomelanistics, if you breed two co-dominant hypomelanistic animals together, you would theoretically expect:
25% Normals
50% Hypomelanistics
25% Super Hypomelanistics

Like I said though, I don't know boa genetics. However, if albino is recessive and hypomelanism is co-dominant that is what you could expect to produce. Keep in mind though that what you can expect is not always what you get.

Yeah, I know the Punit square numbers say that, and that's where he derives his numbers from. I admit that would be the answer if it were true. It's a rough idea, that he is trying make exact.

But I dont't believe the co-dom gene will distribute that evenly, (so as in reality) to come up with 25% each, this is where we dis-agree. It's not predictable, (the co-dom gene), which will get it. Even a litter of 19 would screw up the numbers.
A dominant gene you can predict. It will affect the whole litter. Not so with a co-dom gene, and it doesn't affect half the litter exactly. It varies from what I have read.

Any more opinions? Maybe I've been mis-learned.

Originally Posted by crotalusadamanteus

Yeah, I know the Punit square numbers say that, and that's where he derives his numbers from. I admit that would be the answer if it were true. It's a rough idea, that he is trying make exact.

But I dont't believe the co-dom gene will distribute that evenly, (so as in reality) to come up with 25% each, this is where we dis-agree. It's not predictable, (the co-dom gene), which will get it. Even a litter of 19 would screw up the numbers.
A dominant gene you can predict. It will affect the whole litter. Not so with a co-dom gene, and it doesn't affect half the litter exactly. It varies from what I have read.

Any more opinions? Maybe I've been mis-learned.

Punnett squares only give you odds. There are no sperm and egg sorting facilities, and the outcome is random, just like if you flip two coins you are not guaranteed to get one heads and one tails. Your friend is absolutely wrong.

A dominant gene you can predict. It will affect the whole litter. Not so with a co-dom gene, and it doesn't affect half the litter exactly. It varies from what I have read.

This is not true. One-locus Punnett squares are the same no matter which allele has what effect on the phenotype.

A dominant gene is not inherited any more often than a recessive or codominant gene. The only way a gene is inherited in all offspring is if it is homozygous in one parent or the other.

Also, whether or not a gene is codominant to its wild-type allele has nothing to do with how often it is inherited.

If a specimen is heterozygous for two alleles, each of its offspring has a 50/50 chance of inheriting either gene from it. If a specimen is homozygous at that locus, all of its offspring will inherit that allele from it.

Originally Posted by crotalusadamanteus

I say that there will be +/-half a litter of normals het albino, and +/-half a litter of albinos. Then comes the co-dom Hypo gene.
It will distribute randomly through out the litter correct? Their is no way to tell which offspring will get that hypo gene. So you could get all yer normals being DH Salmons, or all your albinos being sunglow, or any combination in between. It's not a guaranteed ratio.

For what it is worth, I'm siding with you on this one, Rick. Mind you, I am not basing my opinion on personal experiences...just good ol' fashioned common sense. Punnett squares offer a statistical expectation of outcomes - the problem here is that MOST of the reptiles I have encountered did not have a good working knowledge of statistics. Bottom line is that the results are not realistic given the sample sizes most "small" breeders are dealing with. When you are producing babies by the 1000s, and 10s of 1000s, you will probably find that the Punnett results are pretty close.

Serpwidgets is 100% correct.

And I would just like to add....................

Originally Posted by crotalusadamanteus

We all know that the Hypo/Salmon gene in BCI is a co-dominant gene. Correct?

Are we sure about that?

A dominant gene is simply a gene that is expressed or observable in the phenotype in the heterozygous state.

It is all about relationships.

The wild type gene is dominant to the amelanistic gene because wild type is expressed in the phenotype with relation to the amel gene. The salmon gene could be called dominant because it is expressed in the heterozygous state in relation to the wild type gene.

A codominant gene is a gene where BOTH genes are expressed and observable in the phenotype in the heterozygous state. The ultramel cornsnake is a perfect example of codominance.

But since there are no PREDICTABLE and CONSISTENT observable differences in the phenotypes of a salmon boa with one copy of the salmon gene and a super salmon with two copies I propose that salmon is a dominant gene.

A little more...

With a codominant trait you will always have three possible phenotypes. Using the ultramel cornsnake as an example you will have
1. Ultra
2. Amel
and because ultra and amel are codominant in relation to each other you will have..
3. ultramel.

With the salmon trait you can only have two possible phenotypes..
1. salmon
and
2. wild type

Therefore salmon can not be a codominant trait.

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

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

Two alleles can be paired in one of three ways. Let's use the Salmon mutant (S^S) and its wild-type counterpart (S⁺) for example. The three possible genotypes at the salmon locus are:

S⁺·S⁺ Homozygous Wild-type
S^S·S⁺ Heterozygous Wild-type and Salmon
S^S·S^S Homozygous Salmon

If salmon is recessive to wild-type:
S⁺·S⁺ = Normal phenotype
S^S·S⁺ = Normal phenotype
S^S·S^S = Salmon phenotype

If salmon is dominant to wild-type:
S⁺·S⁺ = Normal phenotype
S^S·S⁺ = Salmon phenotype
S^S·S^S = Salmon phenotype

If salmon is codominant to wild-type:
S⁺·S⁺ = Normal phenotype
S^S·S⁺ = Intermediate phenotype
S^S·S^S = Salmon phenotype
OR, as is done in some cases:
S⁺·S⁺ = Normal phenotype
S^S·S⁺ = Salmon phenotype
S^S·S^S = "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.