Spider morph question

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Originally Posted by Mendel's Balls

As a training science educator I like to see people learning bio.....:partyon:

MY Gf (Username: Amy) has some pics of our snake in her gallery.:snake:

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Some great info there! And welcome to BP.net!! It's always great to get knowledgeable folks signing on! Maybe you could wander over to the "Off-Topic" forum and introduce yourself and Amy? We'd love to know more about ya! :handshake:

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Originally Posted by Mendel's Balls

As a training science educator I like to see people learning bio.....:partyon:

MY Gf (Username: Amy) has some pics of our snake in her gallery.:snake:

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Me too. I quite enjoy it and especially if I want to be a breeder and an educator I need to know my schtuff.

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Originally Posted by Mendel's Balls

If you cross a homozygous dominant Spider (SS) to a normal, you would expect only Spider. This is no secret!

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Actually it sort of is. I think most agree that if there is a homozygous spider and it is just like the heterozygous spiders then yes, SS X ss = 100% Ss spiders. The secret is whether or not a homozygous (SS) spider has been proven to be viable and/or what it's like. So you are right, the controversy is on the nature of the homozygous spider but not just whether there is a line of homozygous spiders with co-dominant tendencies but whether there are any homozygous spiders at all.

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Originally Posted by RandyRemington

Actually it sort of is. I think most agree that if there is a homozygous spider and it is just like the heterozygous spiders then yes, SS X ss = 100% Ss spiders. The secret is whether or not a homozygous (SS) spider has been proven to be viable and/or what it's like. So you are right, the controversy is on the nature of the homozygous spider but not just whether there is a line of homozygous spiders with co-dominant tendencies but whether there are any homozygous spiders at all.

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I posted a related question about this in another thread, but I didn't get a response so I thought I would post it here. Does anyone know of any specific dominant traits that are incompatible in homozygous form? Not just with Balls, but with any species?

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Originally Posted by xdeus

I posted a related question about this in another thread, but I didn't get a response so I thought I would post it here. Does anyone know of any specific dominant traits that are incompatible in homozygous form? Not just with Balls, but with any species?

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There are numerous examples of dominant alleles incompatible (or lethal) in the homozygous form.

Yellow coat color in mice is one example. Yellow coat color (Y) is dominant to normal coat color (y). When you cross two hetrozygotes (Yy) x (Yy) over and over again you dont see the expected phenotypic ratio of 3 Yellow: 1 normal. Instead, you see a 2:1 ratio of Yellow to Normal.

The expected genotypic ratios of (Yy) x (Yy) is 1 homo dom: 2 hets: 1 homo recessive. The homo dom dies before birth so you dont get the 3:1 ratio that is predicted by a classic monohybrid cross.

The lethality of the yellow dominant allele has been confirmed by removing the utreus of preganant females of the (Yy) x (Yy) cross. One-forth of the embyros there have been found dead.....

Furthermore,in mice we can easily genotype an adult or embryo by using the techniques of molecular biology to look at the actual DNA sequences....this allows us to quickly determine whether an organism is a het or homo without doing millons of crosses (which is still really easy in mice compared to snakes).

And it just happens to be that in other studies those one-fourth that died in utreo were homozygous yellow dominant when tested by DNA testing!

Another example is the Manx cat with no tail. The dominant allele is lethal in the homozygous state.

As far as the spider goes I would think if you breed a Spider to a normal enough times then you can pretty sure beyond a reasonable doubt that it homozygous dominant....If you breed a spider to a normal and got 20 spiders then there would only be a 1 in a million chance (1/2^20) that your wrong.

I dont know how easy it would be to carry out this experiment. I dont know the typical cluth size from a gravid mother. IS it 7-9? How many breeding seasons can a female have babies in a row? I guess what I am asking is....Does she get worn out after two seasons?

At the same time there seems to be speculation (edit with help of elevatethis, for original see next post) that certain (or all) spider alleles are lethal in the homozygous state.....I know I saw something about "Spider Spinnning".....

I dont know much about that...I'll have to look it up in another thread....but it would make sense if the strange behavior caused by the Spider gene was viable in a single dose (het state) but lethal in a double dose (homo state).

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Originally Posted by Mendel's Balls

At the same time there seems to be suggestive evidence that certain (or all) spider alleles are lethal in the homozygous state.....I know I saw something about "Spider Spinnning".....

I dont know much about that...I'll have to look it up in another thread....but it would make sense if the strange behavior caused by the Spider gene was viable in a single dose (het state) but lethal in a double dose (homo state).

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Making claims like that without providing a link or a place to go to see the evidence you speak of is just, well, not cool. I've read a little bit on this on various message boards but otherwise have NOT seen any kind of real data on it.

I've got a normal girl that exhibits some of the "spinning" traits, but I wouldn't consider her to be a true spinner. The way she moves around is noticably different than the rest of my collection. I didn't even suspect anything was wrong until I got to see spinner in person. I wonder how many other people out there with pet snakes, who don't live breathe and eat the issues around bps ever day like we do, that have spinners and don't even realize it. It makes sense for people to notice every little detail in animals that cost as much as morphs do. With that in mind, is it right to directly associate ANY of these defects (spinning spiders, kinking carmels, etc) with the actual morph without solid data?

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Originally Posted by elevatethis

Making claims like that without providing a link or a place to go to see the evidence you speak of is just, well, not cool. I've read a little bit on this on various message boards but otherwise have NOT seen any kind of real data on it.

I've got a normal girl that exhibits some of the "spinning" traits, but I wouldn't consider her to be a true spinner. The way she moves around is noticably different than the rest of my collection. I didn't even suspect anything was wrong until I got to see spinner in person. I wonder how many other people out there with pet snakes, who don't live breathe and eat the issues around bps ever day like we do, that have spinners and don't even realize it. It makes sense for people to notice every little detail in animals that cost as much as morphs do. With that in mind, is it right to directly associate ANY of these defects (spinning spiders, kinking carmels, etc) with the actual morph without solid data?

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Sorry I wasnt more careful with my words.....it's more speculative than suggestive as you pointed out.

I wasnt tying to make a defiantive conclusion on Spiders.......I was just hypothesizing that maybe the reason why people havent seen or have proof of a homozgous spiders is that it is lethal in the homozygous state. If het Spiders are more prone to Spinning, and that is a big if, then that would make sense.

Thanks for keeping me honest and on my toes....I corrected my error but acknowledged it above as well. The Peer Review on this site works well!:D

I dont know if there is any consensus (doesnt seem like it from this site) on whether or not a homozygous spider exists. Makus Janye Ball Python Site (http://www.ballpython.ca/what_get/dominant.html) shows breeding pairs with homozygous spiders....

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Originally Posted by Mendel's Balls

I dont know if there is any consensus (doesnt seem like it from this site) on whether or not a homozygous spider exists. Makus Janye Ball Python Site

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Thanks for all of the info on the Homozygous Lethal trait. That expression has been thrown around a lot with Spiders, and it always stirs up a big controversy. It's understandable because a lot of people have a lot of money invested in these snakes, and unfounded rumors can have a huge impact on the demand.

The reason I asked wasn't so much directed at Spiders, but rather I was curious about what had been substatiated in actual experiments.

Personally, I don't think the spinning attribute associated with Spiders has anything to do with the lack of a homozygote. From what I understand, Pinstripes are very similar and may not be able to produce a homozygote as well, but seem to lack the spinning quality.

I'm sure a lot of these questions will be ironed out in the next few years as people produce more of these little guys.

Oh, and to answer your question about breeding females, I think generally breeders will try to give their females off a year in between clutches, or at least give them a season off for every two that they breed. A lot probably depends on the individual snake, though, and how soon they are able to get back up to their original weight.

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Originally Posted by Mendel's Balls

I wasnt tying to make a defiantive conclusion on Spiders.......I was just hypothesizing that maybe the reason why people havent seen or have proof of a homozgous spiders is that it is lethal in the homozygous state. If het Spiders are more prone to Spinning, and that is a big if, then that would make sense.

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Ok, well I'll keep it going, and I think I disagree:

If there are so few heterozygous spiders exhibiting the trait, then the chances of EVERY homozygous spider exhibiting this trait in lethal form would be just as slim.

I think the real reason that not many or zero people have made a claim to having an homozygous spider is more political. No one wants to make a claim to having an homozygous spider, and then have it sire normal babies the next season.

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Originally Posted by elevatethis

Ok, well I'll keep it going, and I think I disagree:

If there are so few heterozygous spiders exhibiting the trait, then the chances of EVERY homozygous spider exhibiting this trait in lethal form would be just as slim.

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Its all speculation... but I was thinking of it as the spider allele in a single dose may prone to develop abnormally if subjected to certain environmental stressors......The double dose that the homo domainant has might be too much.....it might push viabiablity pass some point of no return.....

Yellow het mice as far as I know are completely normal and a double dose of this dominant allele leads to complete lethality...so it might not be as unlikely as you think....

The spider allele either way has interesting genetics.....spider also tend to have better presonalities I hear? Smells like this allele does have multiple effects, one of which could be viability.....

Maybe someday there will be a ball python genome project....:P

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Originally Posted by elevatethis

I think the real reason that not many or zero people have made a claim to having an homozygous spider is more political. No one wants to make a claim to having an homozygous spider, and then have it sire normal babies the next season.

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Agree that this is likely and also agree with what you said about how people with morphs tend to more observant about their snakes behavior.