Homozygous Spider Morph

[Egapal]

I guess what I was trying to say is that even though Super's aren't considered Dominant, they should be. Think about it, a dominant means that when paired to a normal you get nothing but the visual het version of that snake.

Dominant is not defined as "when paired to a normal you get nothing but the visual het version of that snake." That's the definition of Homozygous. Homozygous means having two copies of the same gene. If that gene is dominant then you get nothing but visual hets that are the same phenotype as the homozygous parent. If the gene in question is co-dominant then you get nothing but visual hets but that visual het has a different phenotype. That means that they don't look like homozygous parent.

[Egapal]

Oh and as for homozygous spider being lethal. Absence of evidence is not evidence except when evidence would be expected. Basically that means that since basic genetics tells us we should see pairings of spider to spider produce 25% homozygous, we would have many of these animals in the population and thus should see a homozygous spider prove out. Since we don't see that we have to ask the question of where those animals are. Its pretty common to have a lethal gene so this theory is not without precedent. It won't be proven conclusively without a proper scientific test. Ideally this would include genetic testing. So not seeing a homozygous spider is evidence for the lethal theory but its far from conclusive. Not seeing a homoyzgous spider could also be evidence for aliens teleporting them out of the mother before the eggs are layed. Again the reason we are conjecturing its lethal is because we have proof of this phenomena in other species.

[Domepiece]

Oh and as for homozygous spider being lethal. Absence of evidence is not evidence except when evidence would be expected. Basically that means that since basic genetics tells us we should see pairings of spider to spider produce 25% homozygous, we would have many of these animals in the population and thus should see a homozygous spider prove out. Since we don't see that we have to ask the question of where those animals are. Its pretty common to have a lethal gene so this theory is not without precedent. It won't be proven conclusively without a proper scientific test. Ideally this would include genetic testing. So not seeing a homozygous spider is evidence for the lethal theory but its far from conclusive. Not seeing a homoyzgous spider could also be evidence for aliens teleporting them out of the mother before the eggs are layed. Again the reason we are conjecturing its lethal is because we have proof of this phenomena in other species.

LOL, Im going with the alien hypothesis.

[snakesRkewl]

LOL, Im going with the alien hypothesis.

Me too, aliens are stealing our homozygous spiders, AHHHHHHHHHHHHHHH

[Jabberwocky Dragons]

For what its worth, Kevin from NERD says they do the spider x spider crosses all the time and there's no such thing as a lethal homozygous spider mutation. He states this ~1 minute in on the Lethal Combinations Part 2 video (not sure if links are allowed).

Assuming there's no lethal combination, sometimes the simplest explanation is correct (Occam's Razor). There are several unnoticed homozygous spiders spread out amongst the sea of ball python keepers. Their offspring are quickly turned to het spiders by spider x non-spider crosses. Over the past half year, I have read several posts (not a lot but some) by people saying they have spiders or know of people whose spiders produce only spiders but they are quickly drowned out by dissenters. That may be all you get, not some grand coming out by a large breeder with 3 generations of documented records, but just regular people who hit the odds by chance.

I'm not saying I believe this but I just wanted to throw it out as something to consider along with Kevin's take on the lethal combination hypothesis. Personally, I'm leaning towards the alien abduction theory

[WingedWolfPsion]

There not anymore proof of the spider mutation being dominant than it being co-dominant. We list morphs as dominant until proven otherwise.

Here is a part of a write up I did on the spider gene

Actually, there is. NERD did a show recently on lethal gene combinations, and pointed out that champagne appears to interact with the spider gene, and the resulting offspring usually die in the egg, or shortly after hatchling. Those that survive have severe wobbles. That a similar pattern-affecting gene proves lethal when combined with spider suggests that double spider is most likely homozygous lethal. "Proven"? No, perhaps not...but readily inferred, and certainly logical.

I do not recollect them stating that there was no evidence that spider was homozygous lethal.
If spider is highly homozygous lethal, the eggs would die early in incubation, and would be discounted as simply 'bad eggs'. Unless every bad egg from a spider X spider clutch were to be opened and inspected under a microscope to check for abnormalities or a dead spider embryo, and nothing was found, there is no reason to believe that spider is NOT homozygous lethal.

Spider is not dominant, regardless, because if it were, homozygous spiders would be produced. They would look like normal spiders, and when bred to a normal, would produce 100% spiders. This has never happened, so homozygous spiders are different from heterozygous spiders (if they weren't different, they would exist, you see). Therefore, whatever the spider mutation is, it is definitely not dominant.

I do recall hearing that homozygous pinstripes, identical to heterozygous pinstripes, have been produced. That makes pinstripe dominant.

[OhhWatALoser]

Actually, there is. NERD did a show recently on lethal gene combinations, and pointed out that champagne appears to interact with the spider gene, and the resulting offspring usually die in the egg, or shortly after hatchling. Those that survive have severe wobbles. That a similar pattern-affecting gene proves lethal when combined with spider suggests that double spider is most likely homozygous lethal. "Proven"? No, perhaps not...but readily inferred, and certainly logical.

I do not recollect them stating that there was no evidence that spider was homozygous lethal.
If spider is highly homozygous lethal, the eggs would die early in incubation, and would be discounted as simply 'bad eggs'. Unless every bad egg from a spider X spider clutch were to be opened and inspected under a microscope to check for abnormalities or a dead spider embryo, and nothing was found, there is no reason to believe that spider is NOT homozygous lethal.

Spider is not dominant, regardless, because if it were, homozygous spiders would be produced. They would look like normal spiders, and when bred to a normal, would produce 100% spiders. This has never happened, so homozygous spiders are different from heterozygous spiders (if they weren't different, they would exist, you see). Therefore, whatever the spider mutation is, it is definitely not dominant.

I do recall hearing that homozygous pinstripes, identical to heterozygous pinstripes, have been produced. That makes pinstripe dominant.

talk to kevin directly if you want to hear him say it. I would also disagree that that it would make it a most likely scenario, just because something looks similar doesn't make it the same. your using another gene to make the comparison, I don't see that as evidence at all... by your logic how can spider + hidden gene woma be fine? looks like champ has a better chance of being the issue.
champ + spider = not good
spider + hidden gene woma = good
champ + hidden gene woma = not good
the evidence is no more of a stretch, than its completely normal gene and we just haven't had one proved out publicly.

anything else I have to say has already been said, this argument goes round and round. want to skip to the bottom line there is no proof of any theory, so why not wait until there is something worth talking about to come out? you use words like definitely when there is nothing definite about this entire subject......

[WingedWolfPsion]

I said it was logical and likely that spider was co-dominant, and homozygous lethal, and I believe that.

I did say it was definite that spider isn't dominant, because, by definition, there is no difference in phenotype between a heterozygous and homozygous animal, with a dominant gene. The very absence of homozygous spiders means that the homozygous animals cannot be identical to the heterozygous animals--something is different, or they would exist.

Now, this is simplistic, as there quite simply are more options than just recessive, incomplete dominant, and dominant, but without getting incredibly complicated, spider simply can't fit into the definition of a dominant gene, so it has to be something else.

Now, I'm personally unaware of any scenario that would prevent 2 copies of a gene from ever winding up in the same animal, and I'm unaware of any scenario that would enable a snake with two copies of a gene to pass on a normal gene. That doesn't mean no such scenarios exist, but do you know of any such instances? That would, logically, seem to be the only alternative to the idea that homozygous spiders die before hatching.
Obviously, either homozygous animals are created, but don't live, or they are not created. If you believe there are other options, I would be curious to hear what else you think it might be.

I do not think either of the two above scenarios could be said to be present in any normal case of dominance, though.

[OhhWatALoser]

I said it was logical and likely that spider was co-dominant, and homozygous lethal, and I believe that.

I did say it was definite that spider isn't dominant, because, by definition, there is no difference in phenotype between a heterozygous and homozygous animal, with a dominant gene. The very absence of homozygous spiders means that the homozygous animals cannot be identical to the heterozygous animals--something is different, or they would exist.

Now, this is simplistic, as there quite simply are more options than just recessive, incomplete dominant, and dominant, but without getting incredibly complicated, spider simply can't fit into the definition of a dominant gene, so it has to be something else.

Now, I'm personally unaware of any scenario that would prevent 2 copies of a gene from ever winding up in the same animal, and I'm unaware of any scenario that would enable a snake with two copies of a gene to pass on a normal gene. That doesn't mean no such scenarios exist, but do you know of any such instances? That would, logically, seem to be the only alternative to the idea that homozygous spiders die before hatching.
Obviously, either homozygous animals are created, but don't live, or they are not created. If you believe there are other options, I would be curious to hear what else you think it might be.

I do not think either of the two above scenarios could be said to be present in any normal case of dominance, though.

how bout the case where its a completely normal gene and we haven't had one prove out publicly? There has only been one public pin and only one public congo. You do realize what It takes to "prove" out a homozygous dominant animal, correct? It's not out of the realm of possibilities that there just isn't one publicly. The absence means nothing, since there could be homozygous spiders out there, just not proven publicly.

there no more proof of a lethal spider than the scenario above, you keep saying absence is proof..... it's not, i'm sorry.

know what else we haven't seen homozygous of? Avalanche, Banana, Black Belly, Black Head, Black Lace, Calico, Champagne, Coral Glow, Daddy Gene, Desert, Ember, Epic, Fader, Granite, Het Highway, Spark, Josie, Marble, Napalm, Orange Glow, Philistine, Reaper, Shatter, Spector, Sugar, Whirlwind, Whitesmoke, Woma. Are they all co-dominant also since there is an absence of homozygous forms of them, or maybe it's just not proven yet.....

[paulh]

For what its worth, Kevin from NERD says they do the spider x spider crosses all the time and there's no such thing as a lethal homozygous spider mutation. He states this ~1 minute in on the Lethal Combinations Part 2 video (not sure if links are allowed).

Assuming there's no lethal combination, sometimes the simplest explanation is correct (Occam's Razor). There are several unnoticed homozygous spiders spread out amongst the sea of ball python keepers. Their offspring are quickly turned to het spiders by spider x non-spider crosses. Over the past half year, I have read several posts (not a lot but some) by people saying they have spiders or know of people whose spiders produce only spiders but they are quickly drowned out by dissenters. That may be all you get, not some grand coming out by a large breeder with 3 generations of documented records, but just regular people who hit the odds by chance.

I'm not saying I believe this but I just wanted to throw it out as something to consider along with Kevin's take on the lethal combination hypothesis. Personally, I'm leaning towards the alien abduction theory

I do not know if links are allowed either. Please try to post the link. If it gets deleted, please send it to me by personal message. I really want to know what evidence Kevin has for that statement. If he has made many spider x spider matings, then he should be able to do breeding tests to find homozygous spiders. Or could he be just be saying that that such matings produce plenty of spider offspring without specifying whether these spiders are heterozygous or homozygous? Even if all the homozygous spiders die early in egg, spider x spider matings would produce plenty of heterozygous spiders.

"All" is a pretty slippery term. I'd like to see numbers. "All" = 30 means more than "all" = 3.