Re: spider BP's and the head wobble
Quote:
Originally Posted by
WingedWolfPsion
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I think the bias some folks have against spiders that show the wobble trait is due to a desire to believe that what is clearly a neurological defect can't possibly be something that can't be eliminated from one of our favorite morphs...but really, at some point, the facts will have to be faced. Until proven otherwise, I side with the camp that believes the trait is part of the spider mutation itself, and cannot be eliminated. It rarely does harm in any case.
NERD's web-site still lists the mutation as Dominant: http://www.newenglandreptile.com/ner...ns/spider.html
Kevin himself on Reptile Radio also referred to the mutation as dominant.
As far as the morph being "out-bred" -not initially. He line bred the heck out of it initially. I do agree that now the morph is being out bred well. I also own a Spider that's 4 years old & has never wobbled, he dad is wobble free too. The new 'Bee I got in does not wobble & the breeder tells me he has not produced any wobbles from the sire who is also wobble-free...
Does it mean I won't produce wobbling snakes? Not 100%, but it does show there are animals out there without the defect. I'm not so quick believe this mutation can't be improved through selective breeding. Compared with other animals BP morph are new, time will tell.
Re: spider BP's and the head wobble
I'm really really hoping to do some serious research on this over the summer; problem is, it's not gonna be easy to get funding to research a disorder in a selective strain of captive snakes ...
I don't know whether I think the neuro signs are directly linked to the spider phenotype (ie, an epistatic effect of the gene) or not. It's tempting to say so, since it does appear that the spider gene is most likely homozygous lethal. However, even if the "neuro gene" were simply VERY tightly linked to the spider gene, that could still cause the same trends in terms of gene expression. In theory, if the genes are separate, and just super-tightly linked, we should eventually see spiders that don't wobble, with enough outcrossing. If the genes are REALLY tight, however, that might be a one in 1000 chance ...
It's pretty much impossible to know exactly why, physiologically, these animals show these signs, without doing various imaging and diagnostic tests (which, AFAIK, have never been done.) My guess would be either a cerebellar or vestibular lesion. To me, it sounds a lot like cerebellar abiotrophy (where the animal is born with a normal cerebellum, which degenerates over time), or cerebellar hypoplasia (born with a cerebellum already degenerated). That's a total guess, though; in fact, it may not even be cerebellar or vestibular, but could be degenerative demyelination, or maybe some other peripheral neuropathy. (I tend to doubt that simply because it doesn't seem to usually get THAT much worse as the animal ages -- sometimes even improves, from what I've read, but who knows.)
I think that the fact that the signs seem to be so heavily precipitated by stress/heightened arousal is very telling. To me, that suggests something cerebellar and not peripheral ... But hell, what do I know; my class got such a crappy average on our neuro exam Monday I'm surprised I even know that snakes have brains. :rofl:
