Proving Dominant Traits

So this is going to be possibly a beaten topic in other areas, but I did not see any imediate information on this available, so I thought I'd poke a dangerous bear and see what everyone thinks on this matter.

We tend to understate certain examples of dominant traits and need to better classify what we know and understand as dominant and how it truly relates back in the genetic community.

The Basics:

If we look at a Simple Dominance outcome you can say that the spider gene may look something like Xx and normal would of course be xx. Now, having that X makes it show the trait, spider. When we do a simple cross between a spider and a normal we would get the genetic ratios of half Xx and half xx. This is fine and dandy, and is where most people are fine with the concept.

The story of two hets:

Most of you should understand the concept of Het vs Homozygous, and when we refer to simple dominance we know that Hets and Homo individuals should be a represenative of this trait, whatever we may be dealing with, for my example, spider. So in order for us to consider spider dominant and not co-dominant, we need to do a cross between 2 adults that are both spider, this will theoretically be crossing Xx and Xx (again considering this was a first generation production for each, and again assuming simple dominance). Here's what the genetic wizard says about that . . .


Now, if we look at the combos of genes we would be getting a little bit different story, it would look more like 25% Normal, 25% Homozygous (XX), and 50% Het (Xy).

The truth and point:

So we've now broken it down pretty plain and simple, but I challenge you now to cross back EVERY spider produced by that previous clutch and cross it with a normal. In theory, at least 25% should be the Homozyous form, so when you find that individual, it will only be able to pass on an X rather than an x, thus continuing the spider gene.

The problem is, you won't be able to prove it, and the reason is simply that MANY of the morphs we associate as dominant, are actually co-dominant with Homozygous lethality in its super form.

Many people that seek out communities like this one, need to be properly educated about genetics if they want to pursue makin morphs. We also need to be careful about how we deem morphs when considering them for dominant vs co-dominant. For it to truly be dominant, you would still be able to get a super form, though it may not phenotypically be different than the het form, it would genotypically be vastly differnet and thus proveable. Think of a Blue-eyed Lucy (say lesser x lesser). If you breed that beautiful snake to a normal, you will get 100% Lesser offspring because Lucy can only pass on 1 gene. Co-dominant in its true nature usually works with genes. We can consider Lesser Co-dominant, because its super form is controlled by different alleles at the same Loci. However, things like Cinamon need NOT be referred to as Co-dominant, because our knowledge only demonstrates one known allele that can produce a super form, but at the same time we can't just refer to it as dominant because the super form is a different phenotype than it is in its heterozygous form!

Hopefully this doesn't confuse anybody, but perhaps encourages a beter look into this interesting subject. There are MANY factors at play when we mess with genetics and mutations, why do you think that Super Cinny are so prone to kinking? We're not just messing with the color of a snake, but we're also messing with its genetic make up that may very well be controlling something else. One last example would be Jaguar in Carpet pythons. We know that Jag is a form of Het Leacustic, when you produce a super form, it will die before it reaches its first shed, or early on in the stages of development due to poor lung development amoung other factors (Muton, 2011).

Cheers to those who read this fully and appreciate genetics for the science it really is!

2 questions.

1) For anyone to say that the super form of spider is lethal, then won't there need to be bad eggs in a clutch of spider x spider? If all the eggs are good and all of them hatch (for multiple generations) can you not then consider the possibility of the super spider to NOT be lethal?

2) Can you not say that a cinnamon is a co-Dom because also black pastels create the same super, and are x compatible? In the lesser example, I understood that you were saying that Mojave and butters also affect the same gene therefore lessers are a co-Dom? I may be wrong about my understanding of that paragraph.

Anyways good write up and I enjoyed the read!


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Super cinnies will come out kinked if you inbreed too much. Thats why i got mine from different lines. BHB is rumored to have a dominant pin (super form) in which when bred to a normal it produces all pins.

1) If you don't get any slugs that's fine. BUT my point is if you produce a theoretical Homozygous form, when you breed it in that next generation to a normal, you will get 100% spider since it would only be able to pass on the dominant gene since it has two copies. This has been challenged before with a lot of dominant morphs, and yet it has not been proven.

2) Yes, Cinny and Black-pastel can produce the super form I suppose, I have not seen that complex proved out though I may have missed it. If that's the case then Cinny is indeed Co-dominate and that term can be held true.

Glad you enjoyed it!

Mike - If they do that's impressive, but will be next to impossible to prove out, it may very well be a weird situation with that possible super pin. Pinstripe x pinstripe is also one of those lethal combos when you cross into the super form. Otherwise we would have people selling morphs as "Proven Homozygous Pinstripe" etc. etc.

I know that cinny x cinny make a chocolate brown snake. Black pastel x black pastel make a dark almost black snake. A cinny x black pastel makes a halfway black/brown snake. That's all I know. I don't know what the babies would be from a bp x cinny tho. I would assume half and half but I have no idea.


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Quote:

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Originally Posted by reptileexperts

2) Yes, Cinny and Black-pastel can produce the super form I suppose, I have not seen that complex proved out though I may have missed it. If that's the case then Cinny is indeed Co-dominate and that term can be held true.

Glad you enjoyed it!

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A cinny x bp will give you a 25% chance at the super form which is an 8 ball. An 8 ball bred to a normal will give you 50% cinny and 50% bp. (according to WOBP).

That doesnt make sense to me. I would think it would be 25% normal, 25% cinny, 25% bp, 25% 8 ball...

Quote:

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Originally Posted by reptileexperts

Mike - If they do that's impressive, but will be next to impossible to prove out, it may very well be a weird situation with that possible super pin. Pinstripe x pinstripe is also one of those lethal combos when you cross into the super form. Otherwise we would have people selling morphs as "Proven Homozygous Pinstripe" etc. etc.

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Yea true. Like i said it was just a rumour i heard on here one time before. Im not saying they do or dont;)

Quote:

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Originally Posted by interloc

I know that cinny x cinny make a chocolate brown snake. Black pastel x black pastel make a dark almost black snake. A cinny x black pastel makes a halfway black/brown snake. That's all I know. I don't know what the babies would be from a bp x cinny tho. I would assume half and half but I have no idea.


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The shades all vary from brown to black. Ive seen jet black super cinnies before.

Shoot, give us a harder question than that! :D

The definition of Codominance from Cornell is this just as a reference:

Mode of inheritance in which phenotypic expression of two different alleles occurs in the heterozygote as a result of neither allele being dominant over the other.

Again, in relationship to pythons, we can only consider it codominance If and only If muliple alleles can contribute without effecting the other. So in looking at it under a different light, any complex can be considered co-dominant even if they are not on the same loci and contribute to a super form. However, the main issue at hand is going to be dominance in this post, and rectifying that the super forms of MANY of the morphs out there are in fact lethal in their homozygous state.

Spider and Pin in our examples up to this point.