Dominat gene Questions

[rebel750]

Another question..... Com-Dom genes,

Is a Mojave considered a Het? Because from what I have read the Homozygous Mojave would be a Blue Eyed Lucy or the super form of a Mojave.

This stuff is confusing!

[withonor]

I'm not sure this is the best way to explain it.

The dominant genes will always show up.

Co-dominant genes exist together.

So in the case of a bumblebee the spider pattern is apparent and only the color is taken from the pastel. Co-dominant genes mixed together result in a different looking snake than you started with. Sometimes extreme (Super Cinnamon) and sometimes not so extreme (Super Pastel).

[Eventide]

Spider x Spider gives

25% homozygous Spider*
50% Spider
25% normal.

* Note: Depending on whom you talk to, the homozygous Spider either doesn't exist or it looks exactly like a normal Spider.

[OhhWatALoser]

Another question..... Com-Dom genes,

Is a Mojave considered a Het? Because from what I have read the Homozygous Mojave would be a Blue Eyed Lucy or the super form of a Mojave.

This stuff is confusing!

yes het stands for heterozygous meaning it carying only 1 gene, homozygous aka "super" means carrying a pair of genes.

every single co-dom morph is heterozygous, and the super form being homozygous.

when it comes down to it, a dominant morph is only dominant because the super form can't exist for some reason, or hasn't been proven yet. "super spiders" havn't been proven so their considered dominant and it seems they can't exist for some reason, wether it being lethal or not has yet to be proven and most likly never will be.

another reason the super form might not exist is because its sex linked, but I've never herd of that in snake genetics.

but to answer your first question,
spider x normal = 50% spider / 50% normal
spider x spider = 25% normal / 50% spider / 25% unproven, possible lethal super spider

I donno what link your talking about but the genetic wizard can answer any question you have about genetic breedings....

http://www.geneticswizard.com/

[j_h_smith]

I thought I was pretty good at this genetics stuff, until I read this thread.

Jim Smith

[RandyRemington]

Maybe a help

http://ballpythons.ca/genetics_101.html

Basically I think some are confusing the mutation type (co-dominant or dominant) with the genotype (heterozygous or homozygous mutant). Because hets have an unmatched pair of genes there is a 50/50 chance of which copy they will pass to each offspring. As far as we know, all spiders so far are heterozygous for the spider mutation.

Most pinstripes are heterozygous but as the first proven dominant ball python mutation we know that a homozygous pinstripe looks the same. But a heterozygous pinstripe still has a 50/50 chance of giving pinstripe to each offspring even though the mutation type is dominant. Dominant just tells us how the homozygous pinstripe looks in relation to the heterozygous pinstripe.

[rebel750]

RandyRemington....There is not a homozygous spider correct(Im excluding claims of a super)? Then a every spider, a dominant mutation, is het for spider. Am I going in the right direction?

[rebel750]

So the spider being dominant is ultimately making the normal het for spider for that pairing?

[OhhWatALoser]

So the spider being dominant is ultimately making the normal het for spider for that pairing?

can you rephrase that? I don't understand what your asking.... spider being dominant means there is no homozygous (super) form. you breed a spider to a normal and you just get spiders and normals. het spider is a spider.

[RandyRemington]

So the spider being dominant is ultimately making the normal het for spider for that pairing?

I think you where headed in the right direction the post before this one.

Remember that heterozygous means having an unmatched pair of whatever genes you are talking about. Het does NOT necessarily mean normal looking or even half way to something else. Heterozygous just describes the genotype.

Individual snakes have a genotype classification for a given gene, like heterozygous for albino (having an unmatched pair, one with the albino mutation and the other copy of the same gene without the albino mutation).

Dominant is a way of classifying a specific gene mutation relative to another version of the gene (usually the normal or wild type version). It is constant for the mutation regardless of if the individual snake you are looking at is heterozygous or homozygous for that mutation.

The pastel mutation is an example of a co-dominant mutation (some would argue incomplete dominant but that's another discussion). A ball python that is heterozygous for the pastel mutation has an unmatched pair, one pastel mutant copy and one normal for pastel copy. This creates the pastel phenotype (another way of classifying an individual snake by how it looks). So all pastels are heterozygous at the pastel gene, they have an unmatched pair, a normal for pastel version from one parent and a pastel version from the other parent. The pastel mutation is still co-dominant even if you are looking at a super pastel phenotype. It's the genotype that changes from heterozygous to homozygous mutant between the pastel and the super pastel. The mutation type stays the same. In fact it the relationship between how the hets and the homozygous mutant genotypes look that defines the mutation as co-dominant. Unfortunately you sometimes read about the “dominant form” of a co-dominant mutation when really they are talking about the homozygous version and I think this causes much of the confusing misuse of “dominant”.

Pinstripe is the first proven dominant ball python mutation. The mutation type is classified as dominant because the homozygous pinstripe looks the same as the heterozygous pinstripe; both have the mutant pinstripe phenotype.

Spider is a tough one because 20 years after the founder was bought we still don't know the mutation type. If the homozygous spider genotype is lethal it could explain why we haven't seen a public proven homozygous spider yet. It could also just be that no one has been all that interested in producing and proving one. If spider is homozygous lethal I think this would technically count as co-dominant. The phenotype of the homozygous spider (dead, perhaps even before eggs are laid) would be different than the phenotype of the heterozygous spider (cool spider pattern with a tendency to wobble but alive).

So, the normals from a spider breeding are completely normal for spider. Because spider is not recessive, if a ball gets even one copy of the mutation it does not look normal. As far as we know all the spider phenotype balls produced so far are heterozygous for the spider mutation. They have one spider and one normal for spider copy at the spider locus and that's the real definition of heterozygous.

Mojaves like pastels are known heterozygous animals because they are co-dominant so the hets and the homozygous are both mutations but are different from each other.

A pinstripe hatchling from pinstripe X pinstripe would be a 33% chance homozygous pinstripe until breeding results eventually prove it het (producing some normals) or homozygous (producing a large number of only pinstripes bred to non pinstripes).