Reptile & Amphibian Forums

Hello Everyone,

I must admit that since joining this forum I've become even more intrigued by Ball Pythons. Part of this intrigue stems from the many photos of variously beautiful morphs (?). Although, I'm still quite a bit behind on the lingo. (I'm not even sure I used the word "morphs" correctly.) Can anyone point me toward a semi-comprehensive article on breeding and the complexities of morphism? I'd like to finally understand what people mean when they boast "HET" in a sales ad.

Thank You Infinitely,
Chris =/

PS -- I think I came up with a nifty little user name if anyone is looking: Serpendipity. =)

Check out Ralph Davis' website. He has a section on genetics that will get you started.

Todd

http://www.ralphdavisreptiles.com/

Buy or borrow a decent genetics textbook. Paperback copies of Schaum's Outline of Genetics (either third or fourth edition, used) are going for around $5 on the web, I believe.

Going to 90% of the genetics web sites that I have seen is equivalent to asking to be shot in the foot. They are so bad because generally they do not start with Genetics 101. The major exception is www.ringneckdove.com, but it's not introductory. You need to start with a text to work up to its level.

Paul Hollander

I agree that there are some problems with many of the genetics pages out there. I think mine is good. Let me know what you think...opinions welcome. JP
Joe Pociask Pythons - Genetics

AH HA! I finally understand the whole 50% Het and 66% Het thing. Thank you! Now all I have to do is find out about the Double Het thing. Any idea when you'll finish construction on your Dominant and Co-Dominant pages?

Chris

LOL...yeah, dont know when I'll do more. By the way, what people call co-dominance in the snake biz should really be called incomplete dominance (in case you seach out a genetics book.

A "double het" is just a snake that is heterozygous for two traits. To simplify for you, the resultant offspring from breeding two snakes that are double hets are as follows:

1 in 16 chance of being completeley normal
1 in 16 chance of expressing both traits
1 in 16 chance of expressing trait "A" and normal for trait "B"
1 in 16 chance of expressing trait "B" and normal for trait "A"
2 in 16 chance of expressing trait "A" and being het trait "B"
2 in 16 chance of expressing trait "B" and being het trait "A"
2 in 16 chance of being het trait "A" and normal for trait "B"
2 in 16 chance of being het trait "B" and normal for trait "A"
4 in 16 chance of being het for both traits

Confused yet?

No. Actually that makes perfect sense. So if I'm looking for an Albino, and that's caused by a single gene (double recessive alleles), then i need to only look for a Het. If I'm looking for another type of morph that incorporates two traits, such as an albino striped, then I search for the Double Het. Think I got it.

But it makes me completely sick to my stomach to think that i can not buy a beautiful Albino BP for cheaper. Everyone wants $2500 or so. I suspect this is because they expect you to breed it, and they know that after you do, you won't be coming back to them to buy more. This sucks for those of us who aren't really planning on breeding. They should sell neutered or spayed albinos. I bet they'd be cheap and then I could own one of these beautiful creatures for $150. =)

Thanks,
Chris =)

The price is higher than $150 because there aren't enough albinos available to meet the demand at that price. I don't think neutering albinos is going to help increase the supply.

>LOL...yeah, dont know when I'll do more. By the way, what people call co-dominance in the snake biz should really be called incomplete dominance (in case you seach out a genetics book.

A lot of genetics texts are confused about the difference, too.

To really distinguish between "codominant" and "incomplete dominant", you need to know whether the mutant gene makes a functional or nonfunctional product. As far as phenotype goes, both produce a heterozygous form that can be distinguished from the two homozygous forms. For example, pastel (the heterozygous form) can be distinguished from both normal and super pastel (the two homozygous forms). As far as I know, nobody knows anything about what the pastel mutant does biochemically.

Codominant is simply shorter to type than incomplete dominant.

Paul Hollander
Dominance, codominance, and epistasis

So what would a spider be?

My take was that Co-dominant was a pastel. Why? Because it produced a super pastel. A super was dominant.
Now to my knowledge no one has produced a super spider that is when I called a spider an incomplete Co-dominant. Is my logic wrong? If so why?
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RicK @ BbI

Ball Boutique,Inc.
The home of the singing snakes!

The spider would appear to be dominant. This about it this way...albinism is recessive, right. If you have one or two copies of the dominant (normal) allele, you look normal.

In spiders, normal is not dominant, spider is. if you have one or two copies of spider, your a spider....

Make since?

>My take was that Co-dominant was a pastel. Why? Because it produced a super pastel. A super was dominant.

Pastel is a codominant mutant gene. A super is not dominant. A super has a pair of pastel mutant genes, making it homozygous pastel. The usual type of pastel seen has a pastel mutant gene paired with a normal gene, making it heterozygous pastel. There are three different combinations of the normal allele and the pastel mutant allele, and each one has its own phenotype. That's the basic definition of a codominant mutant gene.

As JP wrote, a dominant mutant gene produces the same abnormal phenotype whether heterozygous or homozygous. There are three different combinations of the normal allele and the dominant mutant allele, and they produce only two phenotypes. The phenotype pattern of a recessive mutant gene is the mirror image of a dominant mutant gene.

Using dominant when meaning homozygous codominant is one of the things that has me down on many herper genetics web sites.

>Now to my knowledge no one has produced a super spider that is when I called a spider an incomplete Co-dominant. Is my logic wrong? If so why?

There is no such thing as an incomplete codominant. OTOH, striped in the California king snake and salmon in the boa constrictor seem to be dominant mutant genes with variable expressivity. This does not seem to fit spider, though.

Possibilities:
1) As JP suggested, spider could be a dominant mutant gene. This is my favored hypothesis. If so, the only way to distinguish the homozygote from the heterozygote is to do a breeding test. As a homozygous spider would produce all spider babies when mated to either a spider or normal, a breeder would have an incentive to do the test.

2) Spider is a codominant lethal -- all the homozygotes die before hatching. This sort of thing turns up every so often, though not so far in snakes as far as I know.

3) Nobody has tried to breed a spider to a spider. I don't know who is breeding spiders or what matings have been done. Someone provide data to disprove this, please.

Paul Hollander

simple statement.... a heterozygous is a normal looking ball that carries the gene for the visible morph.
Like Albino, axanthic, clowns to name a few.
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RicK @ BbI

Ball Boutique,Inc.
The home of the singing snakes!

Common usage in this industry is to only use the term het for recessive morphs where the heterozygous animals should be normal looking.

However, in genetics the term technically means an unmatched pair of genes at a specific location and applies to dominant type morphs also. A pastel is heterozygous for the pastel gene (it has one normal copy of this gene and one pastel copy). If it turns out that spider is completely dominant and a homozygous spider looks just like a heterozygous spider then you will probably start hearing about "het spiders" all the time as a way to distinguish them from the similar looking homozygous spider.

I find it helpful to remember the broader definition of heterozygous so that I can apply the same genotype rules regardless of mutation type.

You are correct Randy.....but I was trying to get him past genetics 101. If you read his original post was asking the questions about the ad with the term het. I to this day have never seen an ad for a pastel that said 100% het for super pastel.
JMO
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RicK @ BbI

Ball Boutique,Inc.
The home of the singing snakes!