Quote Originally Posted by OhhWatALoser View Post
doesn't mean its recessive, in fact, if thats the case it would be co-dom. Recessive means the heterozygous form does not show, which it obviously does, the spider we all have in our collections.

There nothing that suggests that anything would happen to the eggs

You're misunderstanding blackcrystal's post. Recessive lethality does not mean that the spider gene is recessive. (And herein lies the problem with the traditional Mendelian classification system of dominant/recessive/co-dom, etc. -- it is WAY too simple to adequately explain genetics as we now understand it, and gets really confusing.)

What it would mean is that whatever causes the homozygous spiders to not be born -- the lethal part -- is recessive. We know that's recessive because heterozygous spiders are alive, and homozygous ones are not.

Basically, you're breaking down the different effects of the one single "spider" gene (the pattern part and the lethal part, whatever that may be) into two separate categories and saying that the spider pattern is dominant while the lethal whatever is recessive, even though they are caused by the same gene. (This is called pleiotropy, when one gene has multiple different effects.)

I like that theory, although I could also argue that the homozygous lethal condition may actually be an effect of the co-dominant neurologic part of the spider gene -- ie, in heterozygous form they are deficient in some protein, and that deficiency causes them to wobble, spin, etc., while in homozygous form they have none of that protein at all and so fail to progress past early embryogenesis.

I also agree with jjmitchell's post (except for the last line; see above) in that I don't see how it's possible for a homozygous spider to just not exist. Now, that IS what I've heard Kevin postulate, and it's also what I was told by another breeder who worked with spiders very early on (that breeder also claimed that spider x spider produced 100% spiders every time, which I don't particularly believe). I just don't buy it, though -- at some point if you breed spider x spider, a sperm with the spider gene is going to meet an egg with the spider gene and something is going to happen. Maybe the embryo forms and then dies (lethality), but something has to happen.

I mean, if someone can think of a reason why a spider sperm and spider egg may just never meet, please let me know; I just can't really picture it.

I really do wonder, though, if we've really honestly done enough spider to spider breedings to say conclusively. It does seem like, after all this time, if a homoz. spider was alive and breeding we would've heard of it. That having been said, how many people really breed spider x spider? As you said, I do believe that they are one of the most outcrossed mutations ... And heck, there's only one homozygous pinstripe that we all know of, and we all know of it because it's owned by a breeder who also does an Internet show, and is very vocal and active within the community. What if the one or two homozygous spiders out there just happen to be owned by breeders who don't get on the Internet that much?