Reptile & Amphibian Forums

the spider trait is dominant right? so spiders are like super pastels as they are the homozygous form? so when a homozygous spider is bred to a normal/wild parent then the clutch would theororeticaly be 100% heterozygous spiders? i can't seem to find these het spiders anywhere? has anyone ever seen them, or no of a site with pics?
thanks

"the spider trait is dominant right? so spiders are like super pastels as they are the homozygous form? so when a homozygous spider is bred to a normal/wild parent then the clutch would theororeticaly be 100% heterozygous spiders? i can't seem to find these het spiders anywhere? has anyone ever seen them, or no of a site with pics?
thanks"

OK, let me see if I can smooth this out. In general, a gene is made up of two alleles. An individual inherits one allele for every [autosomal] gene from each parent.

In recessive traits, such as albino or ghost, the morph is only expressed in the homozygous form (both inherited alleles for the gene are the recessive form), which means that the heterozygotes (only one inherited allele for the gene is the recessive form) appear to be the same as a Normal, since the Normal trait is the more dominant form. The fact that the difference between a Normal and a het cannot be seen visually is the reason that % possible hets are sold; the breeder cannot tell any better than anyone else (until the animal is bred) what alleles the animal in question may carry, so the statistical probability of the animal being heterozygous is given as "% possible."

Dominant and Codominant traits are inherited somewhat differently. Most of the morphs we have found in Ball Pythons seem to be simply inherited (involving only one gene or a few genes that are very closely linked - this includes the recessive, dominant, and codominant traits). What is different about the inheritance of domaninant and codominant traits, is that they are expressed if even one allele of the gene is present.

In codominant traits, such as Pastels, the homozygous form (the Super Pastel - where both inherited alleles for the gene are the dominant pastel allele) shows the trait that both alleles encode/create together. The heterozygous form (the "Pastel" - where only one inherited allele for the gene is the dominant pastel allele) shows a combination of the normal trait and the (homozygous form Super) Pastel trait. This defines a codominant trait; that the heterozygous form expresses one degree of the trait, and the homozygous form expresses a greater degree of the trait. Think of it as if Pastel and Normal are equally dominant, and have to "share" the heterozygous form.

Now, to your question on Spiders. As I have heard it, the Spider morph appears to be a simple dominant trait. That means that if the allele encoding Spider is present at all, whether heterozygous or homozygous, the Spider trait is expressed. Unlike the problem of possible recessive hets, it is very "cut-and-dry."

I have heard several theories proposed saying that perhaps nobody has actually seen the homozygous form of Spider yet, maybe it is lethal and does not survive, etc... but my personal opinion is just that Spider is a simple dominant trait - after all these mutations did not get cooked up by 'Mother Nature' to impress silly humans. That we are so besotted with these mutations is our own preoccupation.

As of yet there is no fast way to know the difference between a heterozygous Spider and a homozygous Spider; the only way to tell is to spend your money and breed one. If it is bred to a Normal, and you have any Normal babies hatch, you know that your Spider is heterozygous. If after 5 years or so of breeding your Spider to Normals, and never seeing any Normals hatch, you can be pretty well assured that your Spider is homozygous.

That being said, nobody in their right mind should buy anything labeled "het for Spider."

I hope this helps. Please let me know if I should explain some of this any better. Cheers.
~Rebecca
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0.1 Dumeril's Boa '04 (Courtney)
0.2 American Pit Bull Terriers (40lb darling lap dogs:Brandy&Mara)
1.2 Ball Pythons
[1.0 '05 Orange Hypo (Specter)]
[0.1 '05 Het Hypo (Sylvia)]
[0.1 '03 Normal (Sue)]

"That being said, nobody in their right mind should buy anything labeled 'het for Spider.' "

This in and of itself is wrong, as every single spider out there is indeed 'het for spider' meaning that it possesses 1 copy of the spider gene, and one normal or other variation(allele) other than spider.

But I see what you were trying to say, that a normal sold as "het for spider" would not contain any mutant gene, since they are dominant/co - dominant and a "het" would appear as a spider.

Hope this clears it up a little,
Dan

So here is the deal with spiders. As of now, no one has proven a single spider to be homozygous, which would mean bred to a normal you would produce 100% heterozygous spiders. The super spider has so much mystery surrounding it, mainly because the only one to really even to have done Spider(het.) X Spider(het.) would be Kevin over at N.E.R.D., and his conclusion pointed in the direction of just dominant(dominant means het and homo phenotypically are the same), but with no super spider being made public (could just be Kevin not releasing info, but highly doubtful) it seems to me theoretically that Spiders are truly co-dominant, with the homozygous form being fatal since none have supposedly been produced. But like I've said before, there would need to be quite a few Spider X Spider clutches studied with average clutch sizes calculated in order to figure something like that out, and there are very few breeders who would be willing to waste a breeding year to try something like this.

Well anyhow hope this helps,
Dan

There are no het spiders. Hets are only available for recessive genes in snakes. Spiders are dominant not co-dom. Co-doms have super forms, regular dominants do not have a super form.

a pastel a heterozygous super pastel? i thought that hets are technically in both ressesive and dominant/co dominant the only difference is that the hets of dom/co-dom are visible where the hets of ressesive are not. i thought i read that at nerd

"Heterozygous" means that the two members of a gene pair are not the same. "Homozygous" means that the two members of a gene pair are the same. A snake with two pastel mutant genes (a super pastel) is homozygous. A snake with a pastel mutant gene paired with a normal gene is heterozygous. There is nothing in these definitions as to the appearance of either a heterozygous or a homozygous individual.

The appearance of the heterozygous form determines whether a mutant gene is classed as a dominant, codominant, or recessive mutant.
1. Dominant - a heterozygous individual looks like a homozygous mutant individual (the form with two copies of the mutant gene).
2. Recessive - a heterozygous individual looks like a homozygous normal individual (the form with two copies of the normal gene).
3. Codominant - a heterozygous individual can be distinguished from both the homozygous mutant and the homozygous normal forms.

This is pretty standard genetics terminology. The problem with herper genetics terminology is that for a long time there were only recessive mutants, so people got to thinking that a het was supposed to look normal. When dominant and codominant mutants started turning up, herpers went off on their own terminology tangent instead of sticking to standard genetics.

Paul Hollander

table - dominant, recessive, and codominant

I explained this before.
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0.1 Dumeril's Boa '04 (Courtney)
0.2 American Pit Bull Terriers (40lb darling lap dogs:Brandy&Mara)
1.2 Ball Pythons
[1.0 '05 Orange Hypo (Specter)]
[0.1 '05 Het Hypo (Sylvia)]
[0.1 '03 Normal (Sue)]