Proving Dominant Traits

[RandyRemington]

It's certainly a long hard project and IMHO with every expectation that it's unprovable. I could look through my old e-mails to get the details they sent me for the first few years but probably better if we can get an update direct from TSK. Just by memory it's only a few clutches of spider X spider and then years of raising up all the spider offspring. I think most or all of the first spiders where females too.

[Nick Mutton]

I could never look at a snake and say, yes that is het daddy, but they are different.

Im sorry but that statement is a complete contradiction, now who is grasping at straws!

[interloc]

Im sorry but that statement is a complete contradiction, now who is grasping at straws!

I think what he meant was if you presented him with a single snake, he couldn't say for certain if it was het daddy. But if there were 2 snakes side by side and one was het daddy and one was normal, he could tell the difference. No need to jump on somebody because you didn't understand a statement.


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[Nick Mutton]

You are also assuming that everyone involved in any spider project must be dishonest.

This is a complete misinterpretation of what I said. Obviously not everyone with spiders is dishonest. And I agree its pointless to mis-represent them now as they are $100 snakes. However it was not all that many years ago that these snakes were $15-18,000 each and that kind of money does provide sufficient motive.

So far 100% of the evidence supports that its a lethal gene and no evidence suggests its dominant. I will go with the preponderance of evidence on this one. You guys can remain optimistic if you want! Sure you can hold out forever I suppose, and demand some sort of impossible to attain proof, but really as has been pointed out, who cares.

You guys are also subjecting this morph to a higher standard of "proof" than any other. The statistical proof that you seek is conveniently impossible to obtain, yet you make no similar demands of statistical proof for any other morph.

I have a new morph (true story) that I proved out two years ago, I went for the super twice this year and in both cases there was no obvious homozygote, yet in each clutch (5 eggs and 6 eggs respectively) there were fertile eggs that died halfway through incubation, one in the first clutch and 2 in the second. I am well aware that its possible that I have a lethal gene here and am trying again with three females this season.

By your logic I should just sell the new morph as Dominant since I cant absolutely prove otherwise? If I get the same results this season (1 female just ovulated) and I lose roughly 25% of my fertile eggs at around 30 days of incubation (again), I still will not have "proven" anything, even though the answer becomes increasingly obvious.

By your logic, I cant say anything with certainty, yet to call it dominant when all the evidence suggests otherwise seems blatantly dishonest.


Nick

[gsarchie]

So far 100% of the evidence supports that its a lethal gene and no evidence suggests its dominant.

The statistical proof that you seek is conveniently impossible to obtain, yet you make no similar demands of statistical proof for any other morph.

There is no evidence to suggest that spider is homozygous lethal, at least not that I am aware of, and the statistical proof is not impossible to gain. Here is what I wrote in another thread:

"Until someone breeds and keeps records of spiderXspider pairings and then attempts to prove out the offspring, no one will be able to form an educated opinion. If people have kept these records as some suggest (and I'm sure some people have) then I would like to see them so that I could interpret them for myself. If somone could compile the data with a sample size (n) of 200 or more, and the probability (p) of producing a homozygous spider of <0.05 or lower, then I would be inclined to belive that it is improbable that any homozygous spiders exist.

Whether they exist or not, no one has proven that the responsible gene is homozygous lethal, at least not as far as I know. There could be other things that have prevented a homozygous form from being produced yet, and there could be some out there that aren't being bred or haven't been "discovered." Maybe they are sterile and can't reproduce? Is sterility common among 33% of spiders that result from a spiderXspider pairing? Short of seperating egg and sperm, taking one each with the spider gene and fertilizing the egg in vitro to see what happens, we won't know for sure."

After reading your post, another way would be to see if 25% of the eggs die during the incubation period, but no one has brought that up in the thread thus far.

Best of luck proving out your morph. Do you have any pictures of it and what have you decided to call it?

[T&C Exotics]

Just to show some numbers on this that I have produced myself. I have bred Spider to Spider 25 times in total, the last time was 4 years ago. Out of all of them I had 1 slug and 3 eggs go bad during incubation. I did use ultra sound and every number is the exact same for follicle count vs eggs/slugs. I was very lucky and hatched 5 males the first year and they were breeding normal females the next year and were not homo spiders. The females that were raised up that were spider and bred to normal males produced the standard outcome. This year is the last year I will be doing these breedings and currently have 91 eggs incubating from those pairings. So we will see. But so far nothing at all has shown any form of lethality or a super form at all. So with the amount of breedings done on this is a decent amount for a base case study and more can be done to add to it. As a side note there were no multi gene animals used through the entire process it was only spider to spider and then offspring to normals.

[Anatopism]

This is a complete misinterpretation of what I said. Obviously not everyone with spiders is dishonest. And I agree its pointless to mis-represent them now as they are $100 snakes. However it was not all that many years ago that these snakes were $15-18,000 each and that kind of money does provide sufficient motive.

Even when they were $15,000 what benefit is there to be gained from "hiding the truth" about a possible homozygous lethal spider (or any other perceived dominant) trait? If you are not of the mindset that anybody involved in a spider project is dishonest, then who are you accusing specifically of being dishonest? Is this something you'd feel comfortable posting about on fauna BOI, or is it speculation only? Regardless of any paranoia and suspicions on the topic, it's still no proof, or even can be remotely considered evidence, towards the conclusion of a homozygous spider.

So far 100% of the evidence supports that its a lethal gene and no evidence suggests its dominant. I will go with the preponderance of evidence on this one. You guys can remain optimistic if you want! Sure you can hold out forever I suppose, and demand some sort of impossible to attain proof, but really as has been pointed out, who cares.

I'm sorry, I guess I got confused and figured since you are so adamant that you KNOW something as fact, that it would be appropriate to request proof... but you're right. Lets remove the word proof entirely, as it really has no place in this conversation. Instead, please show me evidence that supports your theory(and pointing fingers at breeders for telling lies or keeping secrets doesn't count as evidence).

You guys are also subjecting this morph to a higher standard of "proof" than any other.

No, it's that the topic comes up time and time again, and most people are willing to accept that LOTS of morphs are unknown for certain. Most people call spider 'dominant' because it's simply easier, and seems to be the most suitable conlusion at the time, until enough evidence is compiled and presented, pointing towards a different conclusion. People don't have a specific agenda to "defend" the dominant status of the spider gene, it just happens to be topic that attracts quite a few people that claim theory as fact.

The statistical proof that you seek is conveniently impossible to obtain, yet you make no similar demands of statistical proof for any other morph.

I think you missed my bolded sentence previously. The one that said nobody is arguing it isn't lethal. We're all arguing semantics. The argument is that you claim to KNOW that which cannot be known. To KNOW for a fact requires PROOF. But you're right, proof is hard to come by, and since you claim to have lots of evidence pointing towards an incontrovertible conclusion, I ask you again. Please provide this evidence, that does not include the words "dishonest" and does not include stories of a friend who knew a guy, who knows some breeders in canada, who told him about some other guy in Kansas, who bred a spider to a champagne that died.

I have a new morph (true story) that I proved out two years ago, I went for the super twice this year and in both cases there was no obvious homozygote, yet in each clutch (5 eggs and 6 eggs respectively) there were fertile eggs that died halfway through incubation, one in the first clutch and 2 in the second. I am well aware that its possible that I have a lethal gene here and am trying again with three females this season.

By your logic I should just sell the new morph as Dominant since I cant absolutely prove otherwise? If I get the same results this season (1 female just ovulated) and I lose roughly 25% of my fertile eggs at around 30 days of incubation (again), I still will not have "proven" anything, even though the answer becomes increasingly obvious.

By your logic, I cant say anything with certainty, yet to call it dominant when all the evidence suggests otherwise seems blatantly dishonest.

No, you have evidence pointing towards possible lethal homo, and market it as such. More evidence points towards a more probable conclusion. There is very little actual proof in this world, so you label with the most likely answer for the evidence you have, and provide honest information. If more evidence points towards a different conclusion, then you change your theory, and you change your label.

Just to show some numbers on this that I have produced myself. I have bred Spider to Spider 25 times in total, the last time was 4 years ago. Out of all of them I had 1 slug and 3 eggs go bad during incubation. I did use ultra sound and every number is the exact same for follicle count vs eggs/slugs. I was very lucky and hatched 5 males the first year and they were breeding normal females the next year and were not homo spiders. The females that were raised up that were spider and bred to normal males produced the standard outcome. This year is the last year I will be doing these breedings and currently have 91 eggs incubating from those pairings. So we will see. But so far nothing at all has shown any form of lethality or a super form at all. So with the amount of breedings done on this is a decent amount for a base case study and more can be done to add to it. As a side note there were no multi gene animals used through the entire process it was only spider to spider and then offspring to normals.

Very interesting, Tat! Thank you for sharing this information. I would love to be updated on your results

[RandyRemington]

Just to show some numbers on this that I have produced myself. I have bred Spider to Spider 25 times in total, the last time was 4 years ago. Out of all of them I had 1 slug and 3 eggs go bad during incubation. I did use ultra sound and every number is the exact same for follicle count vs eggs/slugs. I was very lucky and hatched 5 males the first year and they were breeding normal females the next year and were not homo spiders. The females that were raised up that were spider and bred to normal males produced the standard outcome. This year is the last year I will be doing these breedings and currently have 91 eggs incubating from those pairings. So we will see. But so far nothing at all has shown any form of lethality or a super form at all. So with the amount of breedings done on this is a decent amount for a base case study and more can be done to add to it. As a side note there were no multi gene animals used through the entire process it was only spider to spider and then offspring to normals.

Wow, I had no idea anyone had done this much to try to prove homozygous spider. Thank you for your diligence on this! One of the theories on why we don't have a public proven homozygous spider yet is that there just haven't been many spider X spider breedings due to lack of interest. Are you ready to put numbers to how many spiders and how many normals were produced from the 25 spider X spider pairings? Even if we are only talking 100 - 200 total offspring the ratio might be significant (i.e. is it closer to 75% or 67%). Of course if you hit on proving a homozygous spider this year that will put it to rest but if not I'd also be very interested in how many potential homozygous spiders where bred failing to prove as 50 - 100 of those could also be a statistically significant sample size. If both stats point toward there not being a homozygous spider then it's very interesting how this can be given your follicle counting. I'm pretty ignorant on the technical details of python reproduction. Are the follicles not yet even fertilized when you are counting them? Someone mentioned something I took to be the possibility that a female spider egg could only be fertilized by a non spider sperm. I don't really understand how that could be but if anyone could elaborate on that I'd be very interested as it would seem the only way to explain these results given the low count of bad eggs and the follicular counts seeming to rule out homozygous spiders dying early. I think TSK's much smaller sample early on happened to have right around 1/4 small bad eggs so I was really expecting that but of course can't argue with actual numbers, especially such a nice sized sample. Did any of the spiders prove infertile? That’s another angle I guess that someone brought up. I once heard someone assert that the definition of homozygous lethal extended to infertile but that seems a bit of a stretch to me but whatever it would be called would be nice to know about.

[OhhWatALoser]

I did use ultra sound and every number is the exact same for follicle count vs eggs/slugs.

There is the "impossible" evidence. I look forward to seeing your numbers. Anyone spending time on this deserves a great deal of respect.

[gsarchie]

I brought up the issue of sterility in a homozygous spider as well as the possibility of a pre-zygotic barrier to a homozygous spider.

In a spiderXspider pairing, where both parents were produced from spiderXnormal pairings to ensure that they were heterozygotes, we can expect 1 normal, two homozygous spider and one homozygous spider. If the homozygotes were sterile then we would expect 1 in 3spiders produced from the spiderXspider pairing to exhibit sterility, which is what I tried to get across in a previous post.

The existence of a pre-zygotic barrier to a fertilization that would create a homozygous spider seems like a very real possibility based on the data given in regards to follicle count vs. egg count in multiple spiderXspider pairings. Since both males and female spiders can produce viable spider offspring when bred to a normal, it is likely that a sperm with a y chromosme and the spider gene may not have the ability to fertilize an egg, meaning that only gametes with an X chromosome can carry the mutation (an X linked mutation?). This could be proven out by seeing if a male spider can father a male spider. If not, you have your answer, but if so, one would have to dig deeper to find out the reason that no homozygous spiders have been produced.