Extreme Genetics

I noticed that the majority of snake breeding takes the Mendellian genetics model. While this model rocks, it's incomplete. What begs the question and is the subject of this post, is the possibility for using crossing over to make new morphs. No John Edwards, this is some fun science.

Alright, So the way crossing over works, is that one gene spontaneously switches to it's sister chromosome during meitosis. So what's that mean to you?

If you have two gene's on the same chromosome, they often appear together. We'll say Blue eyes and the gene to make a leucistic. It's possible that the same gene codes for both(in the case of mojaves) but if you look at the Black Eyed Leucistics that fireballs produce. I might have those backwards, but the idea remains. Blue eyes and White scales might be two different genes. It's possible then that one of the genes would cross over and move to a normal chromosome, not containing say, the leucistic gene. So now you have one gene with leucism, one with the blue eyed trait. Your off spring winds up being a black eyed leucistic when you expected a blue eyed leucistic. If this happens, then one of the normals that popped out would have a recessive gene for blue eyes, and no genes for mojave. Breeding this guy to a blue eyed leucistic would produce .50 blue eyed normal, .50 blue eyed mojave. Wild eh?

The next question is, is this really possible and how likely. The answer depends on the distance the blue eyed gene is from the leucistic gene on the chrosome. The farther they are away, the more likely crossing over becomes. If they're close, the chance diminishes but is still there. So, if you're lucky enough to get a black eyed when you expected blue... you can likely make a really awesome new morph. I don't know a whole lot about different morphs that express two different genes, but if you guys think of any, try thinking of th possibilities and ways to breed it out.


Let me know what you think, or if anyone has heard of the blue eye trait missing.

that's all sweet in theory, but waht are the odds of that actually happening? obviously it hasn't happened yet. Or has it? i mean who's to say that a spider wasn't originally a spider at all. at one point and time it was something else, but since it "crossed over" the new sper gene took dominance and the other died out. this is really something exciting to think about. how sweet would a blue eyed killer clown look? i never thought of this.

The odds depend on the distance apart the genes are in the chromosome... the best way to prove this would be to breed blue eyed leucistics and black eyed leucistics. If you produce black eyed leucistic children, they would all be black eyed leucistic, and bred those children and got 1/2 blue eyed leucistic 1/2 black eyed leucistic you'd prove that the blue eyed gene is separate.... Then it's just a matter of time before blue eyeds bred together produce a black eyed or mojaves produce a black eyed. The other offspring would be the key to isolating the recessive blue eyed gene.

Only one way to find out and that is try! It would be cool to seperate the blue gene. I believe they are having trouble seperating the two traits platty daddy has also. It appears that he has a co-dom gene of the lesser platnim, but also some sort of hypo that I'm not sure if Ralph has been able to get it to show without the lesser gene pressent. Also with that gene it sounds as if it is hard to make additional platty daddies as the birthings don't seem to follow the odds!

If they don't follow the odds, what's probably happening is the genes are far apart on the chromsome and thus very likely to split off. It could be as likely as 50%, beyond that it'd be indistinguishable from different chromosomes... If you know a way I could get ahold of ralph, I'd be glad to send him some info about it.

If the platty has a few recessive genes at work, it could even be multiple it's possible that when it's bred these genes scatter and you wind up with bizarre offspring. Multiple genes on the same chromosome produce results that are much unlike punnet squares predict.

I was actually thinking wrong... each sperm would have a chance of crossing over... so you might have what appears to be a mojave or a normal carrying the blue eyed recessive gene....Basically breeding offspring to leucistics might one day produce a Blue eyed snake with an isolated gene..

Fantastic.

This sounds along the lines of Ralph Davis' "Platty Daddy" and his so called "hidden gene" and the same with NERD's woma's. Some of them carry a hidden gene which is why NERD's woma - Lesser pastel (http://www.newenglandreptile.com/ava...&cat=46&page=1) looks so much different than any others. Could it be that this wild gene is what you are talking about, and it only appears once it's overlapped so to speak?

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Originally Posted by colemaj

If the platty has a few recessive genes at work, it could even be multiple it's possible that when it's bred these genes scatter and you wind up with bizarre offspring. Multiple genes on the same chromosome produce results that are much unlike punnet squares predict.

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The Lesser morph is from the off spring of "Platty Daddy". The super form of the lesser is the blue eyed Leucistics! This extra ressesive gene could be why the super form looks the way it does! A lesser could possibly prove out to be a dom by itself if recessive genes that can be seperated from the lesser are proven to exist. :weirdface Also the last time I checked the only way Ralph was able to make more Platty Daddies was to breed a lesser born directly from platty daddy to a normal looking off spring from platty daddy. I read somewhere that only 3 platty daddies had been made, but I think the publication was a 2006 release, but can not really remember. One way to possibly get the blue eyed gene by itself could possibly to breed two normal looking offspring from "Platty Daddy" together.

Just maybe Ralph has already done this and is trying to get this gene mixed with other morphs to give him a head start in using this gene before he releases the base gene into the public. Wouldn't that just be something a top notch breeder like Ralph to have going on in some back room! :rolleyes:

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Originally Posted by colemaj

What begs the question and is the subject of this post, is the possibility for using crossing over to make new morphs. No John Edwards, this is some fun science.

If this happens, then one of the normals that popped out would have a recessive gene for blue eyes, and no genes for mojave. Breeding this guy to a blue eyed leucistic would produce .50 blue eyed normal, .50 blue eyed mojave. Wild eh?

Let me know what you think, or if anyone has heard of the blue eye trait missing.

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This is a very excellent post, and I think it could bring about some very intersting debate. I understand the theory of "crossing over", however, I have a slight problem with your description above. If crossing over is not using Mendalian theory, then how could you end up with said normal that is Recessive for Blue eyes. If it is recessive, then it is following Mendalian theory.

That covered my issue, but as for the rest of the thread, I think that we could eventually seperate some traits from Ball Pythons for varying reasons, including, to eliminate a "bad" gene, or to put one trait with another, as described in your example. I think if we had some contact with a genetics lab, we could possibly make a Spider that didn't carry the spinning trait, a Caramel that didn't carry the kinking trait. a Green eyed Leucistic, or even possibly a Super Spider (if it is indeed lethal).

Thanks for the thought provoking thread so early in the morning. It usually takes me longer to get the gears turning.

I'm always interested in figuring out more of what's possible
do we know anything about what genes are on the same chromosome?
I was talking about that when we were discussing incompatible lines of...hypo I believe. (About the importance of knowing if they're on the same chromosome, not about crossing over, which can also be important)
The way I understand crossing over (and this is only from AP Biology, so I could definitely be wrong, although my Bio teacher was pretty much the best ever) is that it happens every time, but with only a few genes, so the location of the trait on the chromosome is really important.
Anyway, could be interesting...

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Originally Posted by muddoc

I think that we could eventually seperate some traits from Ball Pythons for varying reasons, including, to eliminate a "bad" gene, or to put one trait with another, as described in your example. I think if we had some contact with a genetics lab, we could possibly make a Spider that didn't carry the spinning trait, a Caramel that didn't carry the kinking trait. a Green eyed Leucistic, or even possibly a Super Spider (if it is indeed lethal).

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That's exactly what I was thinking, after all this debate over wobbling, lol
As for the Super Spider, why do people think it's lethal? Do all spiders produced from spider x spider breeding always have some normal offspring?

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Originally Posted by soy.lor.n

As for the Super Spider, why do people think it's lethal?

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AFAIK, it's simply because there has never been a proven SS.

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Originally Posted by soy.lor.n

Do all spiders produced from spider x spider breeding always have some normal offspring?

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Since the gene is considered dominant, I don't believe anyone has really made a project out of trying to prove an individual spider to be homozygous, since doing so would not be cost-effective, and, even if the subject were male, would take a number of seasons to reach a speculative conclusion, that could be undone at any point if the animal produced normal offspring.

I suppose by watching for crossovers is how we might eventually find what is all part of the same gene and what is just closely linked separate genes. I suspect that blue eyes, kinks, and spinning are all part of the same gene that makes the lesser complex, caramels (and cinnamon), and spiders respectively and can't be crossed out but certainly worth trying.

With the large number of ball python mutations we might eventually find some close linking of separate mutant genes. One speculation is that since it’s taken a long time to produce a true ghost (axanthic + hypomelanistic) that could indicate linking between those two recessive mutations. Maybe we'll need a crossover to make progress toward the double homozygous recessive true ghost. Once we have a crossover to pair two closely linked mutations it will make for some interesting breeding results in later generations.

A good question is why there appear to be so many different mutant variations of the blue eyed white snake gene (lesser, mojave, phantom, Vin Russo, mocha, hidden/dilute). Maybe these are separate but closely linked genes. But given the interactions they have with each other (producing white snakes generally) I'd also guess here that we are talking about the same gene without crossover potential. I think the hidden/dilute allele that pairs with lesser to make a platy is just like the other alleles except that it isn't visible by its self or even when homozygous.

Alright, yeah, I was incorrect about isolating the gene to make the normal blue eyed recessive... they are a possible offspring but it would be hard to know without breeding.

Basically, if you have a clutch of, we'll say two mojaves for BEL. You get 1/4 normal, 1/2 mojave, 1/2 blue eyed leucistic. Now... If the Gene for blue eyes is separate than the leucistic gene, it may have crossed over in a percentage of the offspring. If it crosses over on the normal chromosome of one of the mojaves, you'd have a blue eyed mojove, if it crosses over onto either chromosome for the normal, breeding it to a blue eyed leucistic would produce 1/2 blue eyed mojove's. A blue eyed mojave would have one Mojove/blue eyed chromosome and one blue eyed chromosome. That could be bred out to isolate the blue eyed gene. It's basically a matter of waiting for a blue eyed mojave, or breeding the normals from the Mojave children to mojaves/BEL.

The same goes with spider wobble, etc. The difference is, I'd guess the blue eyed gene is recessive while the wobble might be co-dom/dom.

Now, let me know what you think about this next part. Perhaps Homozygous wobble is deadly, but hetero is survivable. This would explain why no super spider exists.... If you isolated it, you'd have yourself(potentially) a new morph.. or a homozygous spider.

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Originally Posted by colemaj

If it crosses over on the normal chromosome of one of the mojaves, you'd have a blue eyed mojove, if it crosses over onto either chromosome for the normal, breeding it to a blue eyed leucistic would produce 1/2 blue eyed mojove's. A blue eyed mojave would have one Mojove/blue eyed chromosome and one blue eyed chromosome. That could be bred out to isolate the blue eyed gene. It's basically a matter of waiting for a blue eyed mojave, or breeding the normals from the Mojave children to mojaves/BEL.

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You're saying that the blue eye trait is recessive or possibly homozygous co-dominant, so if the blue eye gene crossed over in one, wouldn't you have a mojave that was double het for blue eyes, since what you're effectively doing is pulling one of the mutated allelles from the chromosome that would normally need both copies to express the phenotype, and pairing it up with another non-mutated allelle on a different chromosome? This is a new and interesting concept to me, but I'm a little confused about how the cross over phenotypes would be expressed.

For normal people it would mean breeding it out (this could take years) or waiting for some one else to do it and buy the "hets" for $50,000. it would be some what easier for other people with connections at a lab who could actually monitor chromosome blueprints . the guesssing game would be minimal.

wow this is a great post but my head is spinning so much info its great

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Originally Posted by KCBALLer

For normal people it would mean breeding it out (this could take years) or waiting for some one else to do it and buy the "hets" for $50,000. it would be some what easier for other people with connections at a lab who could actually monitor chromosome blueprints . the guesssing game would be minimal.

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They would still have to map the ball python genome first, before any genes could be seen or studied.

Hey JW, you're the first Ron Paul supporter I've noticed on here!
:gj::salute::gj:
/hijack

To resolve the confusion, I'll try to make this make more sense

During Gamete production, crossing over can happen.. So we'll say you've got your two parental chromosomes here.. I'll Use Be for blue eyes and M for mojave. Below are matched chromosomes

---Be------M----
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Before sperm/egg are produced crossing over can happen so you'd have


-------------M---
---Be------------


Each chromosome would have it's own sperm, so you'd have a sperm with Be recessive/codom gene(I would speculate that it's recessive) And one with whatever other gene/genes gives mojave their flavor.

So we'll say that this animal is paired with a sperm containing a normal mojave set of genes

---Be---------M---
---Be--------------

So now that blue eye is heterozygous, and would be expressed at is in the Blue eyed leucistic, seen below.

---Be---------M---
---Be---------M---

If the other Be chromosome is paired with a normal chromosome you'd get

------------------
---Be------------

I hope this helps.

While it's certainly possible that blue eyes are a mutation of a separate gene closely linked to the gene containing the various mutations that make blue eyed leucistics (mojave, lesser, butter, Vin Russo, Mocha, phantom), it doesn't seem likely given that all these different (with the possible exception of lesser and butter) mutations would be found linked to the same separate blue eye gene. I think it's more likely that blue eyes are just one of the expressions of being homozygous for a mutation of a single gene just like the white skin.

Perhaps a more likely example to demonstrate crossover would be when trying to combine two presumed separate mutations, like axanthic and hypomelanistic. However, again, not particularly likely for any given pair with the limited data available yet.

I agree, and my knowlege of morphs is admittedly, rather low. I think that accounting for the possibility of crossover when breeding in the future might come in handy. Maybe before too long it won't be very expensive to sequence the BP Genome. Wouldn't that be a fantastic source of information?

Absolutely the possibility of crossovers should be considered. Ball python people are just starting to think of multiple mutant alleles and linking/crossovers will be very extreme should we eventually encounter it (and I suspect we will). I did hear of a case with leopard geckos once that might indicate two linked mutations and a crossover but I don't remember the details. Also, years ago I wondered if green and labyrinth might be linked in Burmese pythons but I've not followed that close enough to know if it's yet been disproved.

I don't personally think the Blue Eye gene is separate for one reason. Blue eyes can easily be explained by Leucism. The dark coloring of the eye is pigment, just like in humans. So Leucism is just working with the eyes as well as the skin pigments.

From my eye doctor. I have blue eyes and when he was dilating them he said it should be really quick and I asked why. He explained that blue eyes lack pigment that dark eyes have, so the dilating solution doesn't have to go through as much pigment.

Hope that helps.

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Originally Posted by colemaj

I agree, and my knowlege of morphs is admittedly, rather low. I think that accounting for the possibility of crossover when breeding in the future might come in handy. Maybe before too long it won't be very expensive to sequence the BP Genome. Wouldn't that be a fantastic source of information?

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there are a ridiculous amount of animals that have already been sequenced, I'm not sure if BP's are one of them. but then the question becomes: so what? how do you aim to find the locus of certain genes coding certain traits?

JonV

One thing I think we could use would be a commercial paternity test for ball pythons. I searched a couple years ago and found they even had tests for some fish. With the very real possibilities of retained sperm and perhaps even parthogenisis a paternity test could be good insurance with recessive mutation. It could also serve as a deterrent to theft as even the offspring of stolen animals could be identified.

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Originally Posted by Brimstone111888

I don't personally think the Blue Eye gene is separate for one reason. Blue eyes can easily be explained by Leucism. The dark coloring of the eye is pigment, just like in humans. So Leucism is just working with the eyes as well as the skin pigments.

From my eye doctor. I have blue eyes and when he was dilating them he said it should be really quick and I asked why. He explained that blue eyes lack pigment that dark eyes have, so the dilating solution doesn't have to go through as much pigment.

Hope that helps.

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But what about black eyed leucistics?