Proving Dominant Traits

[RandyRemington]

I think snakes use the zw sex chromosomes like birds, not the xy like mammals. Further, I think the females are the zw that determines the gender (zz male, zw female) of the offspring.

I know my original spider pair came from the same male spider to two normal girls. I just hatched a spider combo female from a spider female bred to a non spider male last night. There looks to be one more spider combo in the egg, I'll let you know if it happens to be male.

It would be very interesting and unexpected to me (but then what do I know) if somehow a spider sperm can't fertilize a spider egg. But it certainly would explain the results (or lack thereof) seen so far. I think the infertile super spider might be a more precedented explanation so will have to see what tattlife2001 has to say about that (i.e. have all the possible homozygous spiders been able to reproduce or are upwards of 1/3 failing?). If that turns out to be the case would be interesting how to categorize the mutation (is it still co-dominant lethal even if the homozygous looks the same because it is different in that it's removed from the gene pool by being sterile?). Anyway, jumping ahead, will need to hear some numbers on possible homozygous spiders reproducing first.

[paulh]

A few years ago I helped a professional geneticist work on his hobby project -- a similar project on the crested mutant gene in zebra finches. He mated crested x crested to try to get homozygous crested of both sexes. Then he mated the possible homozygous crested to a normal of the opposite sex. When normal offspring occurred, he marked that possible homozygous crested as a known heterozygous crested. He ended the project with 25 matings that produced either normal offspring or both crested and normal offspring. Zero matings produced only crested.

My point is that 5-10 matings are insufficient for the statistics.

[gsarchie]

My point is that 5-10 matings are insufficient for the statistics.

I don't think anyone is arguing that an "n" of 5 or 10 would be sufficient, are they?

I've never heard of the wz before but I was looking at a breeder's pairings online and saw where a spider male produced both male and female spider offspring when bred to a normal female, so there goes that theory.

[RandyRemington]

Paul, so after 25 33% chance possible homozygous animals in a row failed to prove did the breeder decide it's a homozygous lethal mutation? Did ya'll notice about 1/4 bad eggs from the het X het breedings or any infertile possible homozygous animals?

[reptileexperts]

It seems to be avoided that there is a possibility that no slugs would be generated, that a matter of non-fertilization could occur in some cases blocking egg development. . .

Again guys, the point of this discussion was to touch a topic that doesn't seem to get much touching. When we deal with genetics we tend to over simplify the situation and this leads to ambiguity in the community that leads to a poor understanding of what's really going on with snake morphs. Some morphs can be quite easy to understand like in the case of recessive genes where we understand perfectly that this follows simple dominance genetics. Things that we lump as dominate though are not being defined within proper reason. We can call any gene that shows up or even "blends" dominate, as long as the phenotype can be observed on any given animal that contains the gene. But other than a dominate gene, we can not call it a simple "dominate" trait. The purpose was to encourage people to draw lines with what we can, and can not understand so that we can have the "many eyes effect" on the problem and come to a conclusion based on the available information. Need I remind the community that as in chemistry, sometimes zero is a significant number, and in Biology, sometimes 0 has meaning. For us to have zero homozygous spiders / pinstripes in the ball python community, we can safely conclude that these animals are not capable of producing homozygous offspring, it is safe to assume that it is lethal in it's homozygous form. Does this make the definition of Dominant false? Well, Yes and No, does it qualify it as Co-dominate? Again, yes and no. It all depends on how we define each term within the community.

This thread is not meant to be a war on breeders who lie and misrepresent facts, but is more of a war on the language we use to define new morphs. Whether or not we use this language to benifit new morphs coming into the community or not is another story. Perhaps one should only refer to morphs as the genes they contain instead of lumpng them as a heridability type. Dominant Genes just mean that the trait is shown with one copy of the gene, it may or may not look different with 2 copies, that's beyond the scope of dominant gene, recessive just means that it is hidden in the presence of a dominant gene on the same loci, because recessive traits are so easy to understand, I don't fear any ambiguity to their languag .

So lethal, infertile, non-producing, a myth, godzilla, bigfoot, whatever, let the lack of evidence stand as evidence for the case against defining a trait as dominant, and let breeders acknowledge the presence of fatal genes, or at least "non-existent homozygous" forms. Will it take work, sure! Will it pay off? Probably not . . . But hey, it's part of the experience, after all I started breeding reptiles to learn and enjoy the hobby, now I get to breed for a profit, but it doesn't mean I can stop learning or enjoying it. Take that to the bank and recieve your two cents . . . or don't . . .

[OhhWatALoser]

It seems to be avoided that there is a possibility that no slugs would be generated, that a matter of non-fertilization could occur in some cases blocking egg development. . .

seems to already be addressed actually....

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

For us to have zero homozygous spiders / pinstripes in the ball python community, we can safely conclude that these animals are not capable of producing homozygous offspring, it is safe to assume that it is lethal in it's homozygous form

Why are you still on about a lethal homozygous pinstripe, when not only is there zero evidence of it, there is a case of a homozygous pinstripe.....

Now ill try to look past the fact twisting and repeat misinformation and lets actually look at what you claim is your concern.

This is how the general community classifies morphs.


Obviously this is a problem, here is my proposal


problem?

[wwmjkd]

you realize that the terms we use, the vernacular of the trade including most all reptiles and not simply ball pythons, are not meant to be scientifically accurate, correct? they're meant to be expedient and convey a commly understood meaning so that everyone is on the same page, or at least reading the same book.

are co-dominant and incomplete dominant synonymous terms? of course not. but we use them in the trade interchangeably. it's just how the terminology has developed. I am still not sure what your point behind these discussions is, but it's a futile mantle to take up in my opinion. especially when you inject other information without anything to back it up.

it's an interesting idea, but one I don't think is fully formed or worth the debate.

[T&C Exotics]

Here are some of them numbers so far and my opinion on what is really going on with the spider gene.

194 spider to spider offspring of those there were 153 spiders, was the sex ratio. So that is 78.86% spider offspring hatched. So our of those numbers you can see the ratio of spiders. So that puts that to rest. There is no fatal gene at play at all if there was there would be something in those numbers to back it up. Next is the offspring from the spider to spider pairings being bred to normals. I have done that with every single one and as stated the rest are waiting to hatch this year. So far there have been the expected odds mostly split in half of normal to spider ratio. I do not that the exact number of offspring on hand but it was aright around 53% spiders produced. So unless these 91 eggs hatch and something throws all spiders, which would I then would have to breed it again next year to prove it wasnt a fluke, then it is proven that we are still not knowing exactly what is going on with the spider gene. I may not ahve the scientific terms like everyone else but something that makes sense to me is that when the spider gene is present nothing else can attach its self to the same location in the DNA. I think I will be going with that statement rather than anything else because from what I have seen that would appear to be the case.

[RandyRemington]

Again, wow, just wow. The work to raise up 153 potential homozygous (33% chance) spiders must have been astronomical. Just because I couldn't come up with a theory to explain how there could be no proven homozygous spiders without it being homozygous lethal means nothing compared with the actual numbers. Of course 1,530 would have been better but already you have me trying to come up with new theories. Letting the data push our imaginations might be how we'll figure this one out.

So do I understand right that with the eggs incubating this year all or almost all of the potential homozygous spiders will have produced? The infertile homozygous spider theory would expect about 50 of those not to have been able to produce but if you are well over 100 and closing in on 150 I think we can put that theory to rest.

While testing out the possible homozygous spiders if you happen to have separate results for male spider to normal for spider from female spider to normal for spider I'd be interested if both where around 53% or if male spider to normal female was a lot higher. If spider sperm swim faster or otherwise are advantaged in fertilizing eggs it could explain your 78% spider ratio in the spider X spider clutches even with homozygous spiders somehow not making it (hard to explain the follicular count against that though).

Another wild theory I just came up with is parthenogenesis. Did a lot (like 25) of the male possible homozygous spiders throw very high spider ratios but eventually had just one or two normals disqualify them from the hunt for a proven homozygous? I've long wondered if female ball pythons might regularly produce parthenogenic babies. For this to be happening and disqualifying actual homozygous spiders (because they aren't the father of all the babies) it should be noticed first in known homozygous animals like leucistics and super pastels. Do these regularly produce a few normals and no one talks about it because it's so messy for the market? Problem with this theory is that it doesn’t explain how the expected roughly 25 homozygous spider females failed to prove (unless babies sometimes only get genetic material from dad by the same mechanism I'm proposing they sometimes only get from mom).

[gsarchie]

Another wild theory I just came up with is parthenogenesis. Did a lot (like 25) of the male possible homozygous spiders throw very high spider ratios but eventually had just one or two normals disqualify them from the hunt for a proven homozygous? I've long wondered if female ball pythons might regularly produce parthenogenic babies. For this to be happening and disqualifying actual homozygous spiders (because they aren't the father of all the babies) it should be noticed first in known homozygous animals like leucistics and super pastels. Do these regularly produce a few normals and no one talks about it because it's so messy for the market? Problem with this theory is that it doesn’t explain how the expected roughly 25 homozygous spider females failed to prove (unless babies sometimes only get genetic material from dad by the same mechanism I'm proposing they sometimes only get from mom).

I have never heard of cases of parthenogenesis occuring in balls, or any snakes for that matter, and there is definitely no way that babies could get genetic material from dad only.