Reptile & Amphibian Forums

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 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. if you bred a normal "het" hypo to a normal wild type boa, the babies would get 1 allele from each parent. So the genotype of the hypo babies would be 1 hypo gene, and 1 normal gene. which is why if that "het" hypo baby was raised and bred to another normal wild type boa, the phenotype of the litter would be approximately 50% "heterozygous" hypos and 50% normal. As opposed to a homozygous hypo bred to a normal wild type, would produce a litter of 100% "heterozygous" hypos. Hence why a hypo het albino is called a DOUBLE-het sunglow.

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.

Very quickly, I have the definition of Heterozygous from the book Designer Morphs, by John Berry.

"Hetero means different. Having two different alleles for a genetically inheritable trait. Thus, although heterozygous snakes carry the gene or inheritable traits of the particular morph they represent, they look like the wild type. Some hets carry or show genetic markers but these are not always reliable. Designer morphs with multiple unmatched mutant allele pairs are referred to as double hets or even triple hets."

Now, my personal opinion, that definition is rather poor, but I had the book in front of me, and it gets the point across.

Nowhere in the defination of heterozygous is the word recessive ever used. Because 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.

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.

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.

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.

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

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

- F1 Hypos are technically considered "heterozygous" hypos

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

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.

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.

Thanks in advance
Tony

Wow... you're absolutely correct. I may have missed something, but everything I read was totally right. A normal hypo has the genotype "Hh" (or whatever letter you want to use). It is therefore heterozygous and if bred to a normal snake would produce half hypos/half normals. A super hypo is HH and can therefore only pass on the hypo allele (but the babies would all be "Hh" hypos, not supers.) Hetero and Homo have nothing to do with dominant or recessive, it simply depends on the nature of the particular morph.

For example, when dealing with the HYPO morph (a dominant morph) you can get:
HH= super hypo
Hh= hypo
hh= totally normal animal (no hidden genes)

And when dealing with the ALBINO morph (a recessive morph) you can get:
AA= totally normal animal (no hidden genes)
Aa= normal-looking animal that CARRIES the albino gene
aa= albino

Therefore, the difference between dominant and recessive genes is that a Dominant "Het" displays the morph, whereas a Recessive "Het" hides it and looks normal.

As far as your explanation of dom and co-dom, the hypo and motley morphs are great examples. A motley is technically Het for the solid black super motley...Just like a Yellow Belly ball python is Het for Ivory.

It's hard to explain Punnett squares to people, I've almost given up on trying to explain them to my boyfriend. Good luck though!

~kasey

The only thing i would disagree to is that you can get Homogenous hypos in a litter of F1s, if both animals in the P generation were at least heterogenous for hypo(Dominant form of hypomelanism). And everything else would be spot on. I'm not an expert, never took a class, just a boa enthusiast.
Andrew

there is one misleading point:

F1 Hypos are technically considered "heterozygous" hypos

Untrue as a homozygous F1 hypo could be created from any two non sibling hypo's including two non sibling homozygous hypos!!

The filial (sp?) nomenclature is:

P1 original unrelated parent animals

F1 ofspring from that pairing (by definition, EVERY animal is at LEAST a F1)

F2 = offspring from two related (I interpret that as sibling) F1's

F3 = offspring from two related F2's

etc. etc.

ANY time you breed a Fx to an unrelated (non sibling) animal, both revert back to P1's
-----
Thanks,

Dave Colling

www.rainbows-r-us-reptiles.com

0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)

LOL, to many snakes to list, last count:
21.29 BRB
19.19 BCI
And those are only the breeders

lots.lots.lots feeder mice and rats

in order to get lets say.... an F4 hypo, we would take 2 unrelated hypos (P1), breed them, and the offspring would be F1s. we then would take 2 siblings from that litter, breed them to eachother.... (F1 x sibling F1) and would produce F2s... Then take F2 x sibling F2, and produce F3s, and so on. So all of the Filials would have to be siblings to the snake they are breeding to. Basically a lot of generations of insest. Is that how it works? I've always been confused as to how the filials worked.

Um, let me think......YUP!

And dooesn't have to be from same litter.

If you started with two boas and labeled every one of their offspring each year as "F1" then in the future anytime you bred two "F1"s together would then have F2's any of those F2's when bred together (cousins even?) would be F3's etc.

Line breeding is valuable to get and/or refine morphs but new fresh bloodlines IMO MUST be crossed in from time to time!!
-----
Thanks,

Dave Colling

www.rainbows-r-us-reptiles.com

0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)

LOL, to many snakes to list, last count:
21.29 BRB
19.19 BCI
And those are only the breeders

lots.lots.lots feeder mice and rats

I like this forum. There are obviously very thoughtful, intelligent and passionate people responding to the threads. Thanks to all...this makes the forums more helpful and enjoyable.

I was about to respond to the general genetics question when I read Dave's post and decided to elaborate with my two cents. The line breeding (selective breeding) of morphs is not that much different than what the kingsnake/cornsnake breeders have done for 20 years to refine the look they are going for. The reason that the F3's, F4's and F5's are nicer is probably because the breeder SELECTIVELY picked the nicest looking babies (morphs) in each litter to breed together. I doubt that the higher F generations would be sought after if the breeder selected for the most drab offspring with poorly defined markings to propagate the next generation. There is definitely an element of inbreeding here as you work toward 'fixing' the genes and making the production of the traits you are selecting for more reliable in the future offspring. BUT I cannot underestimate the power of a diverse gene pool. My thought is that you should start with high genetic diversity (or outcross your line with phenomenal 'normals') before you embark on line breeding (inbreeding) ventures. Also, even if you are on F20....if an unrelated animal (morph or nice normal) has characters that you really like, ...incorporate it into your project. Although you will return to F1, they will be VERY NICE F1's because of all the selection that went on during the past 20 generations. I would consider these offspring sort of a parallel bloodline that has added diversity from the new unrelated parent.

Since I have already gone off on a tangent, I will not respond to the initial post but to say that I have more college genetics than I care to have and I think the post is correct. .... But I do have problem with using the term hypomelanistic for the 'salmon' hypos.... there is a reduction in black to be sure, but I also think there is something that intensifies the red pigment!!!! Otherwise a sunglow would not have additional red pigment and would look very similar to an albino.

This has probably already been discussed, and is a discussion for a separate thread, but the term always bugs me a little.

Thanks guys,
Enjoy your week,

Bryan Hummel
Rainbowboas.com
210_218_7915

Ok I understand calling normal hypo's heterozygous.
I also think that beginners should keep het and co-dom or dom out of the same sentence all together.
Heres what I dont get. I am no college grad, I know boa genetics as well as anyone from a non-technical stand point. But to me any mutation that yields 50% visuals in the first generation and supers if those sibs are bred together should be co-dom or incomplete dom. A spider or pinstripe ball is considered dom because there is no super form. There is a super form in hypo's whether or not you can pick them out of the crowd to me is irrelavent.
Paul and Dave you guys know way more than I do from a technical stand point (I cant even spell technical or irrelavent.LOL) so I'm not saying your wrong and I'm right. It just doesnt make sense that a spider ball is dom because there is no super but in every other "co-dom" mutation there is a super its just that hypo's are the only ones you cant pick out from a crowd so this makes them dom???
-----
1.0 Poss super PC Salmon 05 (Rich Ihle)
0.1 Dubay Pastel 04 (Clay English)
1.0 Sharp Albino 05 (Mike Wilbanks)
0.1 Normal BCI 04 (????)

Well, not familiar with ball morphs but, IMO from what I've gleamed about genetics

Dominant = Two possible phenotypes:

1, Normal, having 2 normal genes
2, Morph, having one or two mutant genes, can only prove out by breeding.

Codominant, having multiple distinct morph phenotypes:

1, Normal, having 2 normal genes
2, Heterozygous Morph, having one each normal and mutant genes.
3, Homozygous Morph, having two mutant genes.
-----
Thanks,

Dave Colling

www.rainbows-r-us-reptiles.com

0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)

LOL, to many snakes to list, last count:
21.29 BRB
19.19 BCI
And those are only the breeders

lots.lots.lots feeder mice and rats

>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

and also everybody else for their input. I'm sure this will not be the last we see of this genetic discussion, it seems to come up randomly every few months. But that's why we are all here right?
Tony