I did a write up on the spider, double check it for me?

[OhhWatALoser]

http://en.wikipedia.org/wiki/Dominance_(genetics)

http://en.wikipedia.org/wiki/Gene

http://en.wikipedia.org/wiki/Zygosity

http://en.wikipedia.org/wiki/Allele

???

[Serpent_Nirvana]

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?

[Serpent_Nirvana]

Also, if you are looking for criticism on the writeup in general, I think that the last couple of paragraphs regarding the wobble come off as a bit defensive. I have spiders, but at the same time I do think there is a lot of room for debate on the ethics of propagating them. I don't think it is fair to brand those who are opposed to their propagation as closed-minded and hypocritical.

I think that it might be better to explain that the majority of spiders have very minor clinical signs, eat and breed great (suggesting that they are thriving, unlike the pearl), and that the severely affected animals are few and far between. Let readers draw their own conclusions as to the ethics of breeding spiders -- those who are against it will continue to be against it regardless of your "official" position in the writeup, and taking up a defensive position looks a bit confrontational IMO.

[sho220]

That having been said, how many people really breed spider x spider?

Maybe not now, but early on??? Probably just about everyone that had a male and female Spider of breeding size/age...Who wouldn't want to create a Super Spider...?

[OhhWatALoser]

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?

you guys can't call phenotypes different things whent hey are caused by the same gene. while gene cause different phenotypes. we classify genes as recessive, co-dom and dom, not phenotypes.

you can't call the lethal part (if it exists) recessive unless you call super pastel also recessive because it doesn't show in the heterozygous form. this is not how we classify genes.... im sorry its just not. spider is dominate as of now, if we find out its lethal in homozygous(super) form its co-dom. i mean its the exact definition of co-dom, different phenotype in between heterozygous (spider) and homozygous (dead).

While i agree with the rest of what you said is possible, nothing points to it except "we havn't seen one yet" so that about where the debate ends as far as i can see

[OhhWatALoser]

Also, if you are looking for criticism on the writeup in general, I think that the last couple of paragraphs regarding the wobble come off as a bit defensive. I have spiders, but at the same time I do think there is a lot of room for debate on the ethics of propagating them. I don't think it is fair to brand those who are opposed to their propagation as closed-minded and hypocritical.

I think that it might be better to explain that the majority of spiders have very minor clinical signs, eat and breed great (suggesting that they are thriving, unlike the pearl), and that the severely affected animals are few and far between. Let readers draw their own conclusions as to the ethics of breeding spiders -- those who are against it will continue to be against it regardless of your "official" position in the writeup, and taking up a defensive position looks a bit confrontational IMO.

maybe if i put the words "I feel" in front of it? tho it is pretty much the definition of hypocritical lol. and yes this is exactly what i was looking for ty

how would you feel it reworded this way... If you don't like them, no one is forcing you to own or like them, but if you think there is something wrong with others owning them, I feel that is closed minded and hypocritical. This morph has been doing great in the ball python world since 1999

[Serpent_Nirvana]

maybe if i put the words "I feel" in front of it? tho it is pretty much the definition of hypocritical lol. and yes this is exactly what i was looking for ty

how would you feel it reworded this way... If you don't like them, no one is forcing you to own or like them, but if you think there is something wrong with others owning them, I feel that is closed minded and hypocritical. This morph has been doing great in the ball python world since 1999

I mean, I think it depends on what you're planning on using it for. If you're planning on making a web page with morph writeups that is heavily colored by your own opinions -- a bit more like Ralph Davis's site -- then that's fine, and frankly you can do whatever you want ... Heck, you can say whatever you want no matter what you're using it for, but IMO if you're looking to create an impersonal database of morph knowledge, I wouldn't put anything terribly opinionated.

I guess the thing is, I really don't see how it's hypocritical for someone to disapprove of breeding spiders (unless the person also bred, say, fainting goats or neuro Enigma leopard geckos -- then it WOULD be the definition of hypocritical!). Closed-minded, maybe, though I don't think it's that, either ...

Also, the terms dominant and recessive DO refer to phenotypes. NOT genotypes. That's a common misconception. Therefore, it is perfectly possible for one given phenotypic manifestation of a gene to be dominant while another is recessive. And if you don't believe me, it is even on Wikipedia, the Source of All Knowledge of Everything (okay not really but it IS on Wikipedia):

http://en.wikipedia.org/wiki/Dominan...is_dominant.3F

[blackcrystal22]

as far as no homozygous form existing.... It is a gene that affects an allele with locusts..... just like everything else.... To think that there is no way for an animal to inherit a gene from both parents is ridiculous...... I dont know if the homozygous form is lethal, I personally dont think any of us do... The woma gene is homozygous lethal we see the offspring fail to thrive.... There are a million threads on homozygous lethal spider and the only conclusion we ever seem to come up with is simply we dont know.... As far as recessive lethal we would not see the spider pattern show in a heterozygous animal if the gene was recessive.

You obviously don't understand a word I said. The gene is recessive for lethality, but dominant in nature when the animal lives.

Recessive means that the trait needs both alleles to exist. In this case, the trait of lethality is recessive because it only happens with both alleles. The spider coloration itself is not recessive, but is associated with the lethality when both alleles are present.

For example, the normal gene becomes a recessive gene when paired with the spider gene because the spider gene acts dominant. Genes can change from dominant to recessive in the presence of other dominant genes.

The day you can breed and prove a homozygous spider, you will disprove the idea of recessive lethality for that gene. Pinstripes were also thought to be like this but Brian at BHB claims to have a homozygous pinstripe, so we'll have to wait and see if that proves out. (You really need 4-5 generations of clutches with all pinstripe offspring to convince.)

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.

co-dom means the heterozygous and homozygous form are different. which if it was lethal, het would be spider and homozygous would be dead. still homozygous lethal anyways. the "XX" means homozygous, has nothing to do with recessive, co-dom, or dom.

Way I see it, it doesn't change the odds, sure it changes the ratio of things that actually come out of eggs, but as far as follicles go you still have the 1:2:1 ratio.

That's assuming its even homozygous lethal which there is next to nothing that suggests this lol.



There nothing that suggests that anything would happen to the eggs

You didn't understand what I said either. Read what I wrote above.

Also there are a lot of other types of genes that have the heterozygous and homozygous form as different traits. I'm not going to teach you all of them, you can go take a class on genetics for that.

I'm trying to understand what you're saying, but it's really confusing.

co-dom means the heterozygous and homozygous form are different. which if it was lethal, het would be spider and homozygous would be dead. still homozygous lethal anyways. the "XX" means homozygous, has nothing to do with recessive, co-dom, or dom.

I even got out my genetics notes for you.
Codominance means that both traits are present in the F1 generation but only one shows. A lot of ball python genes are actually Incomplete Dominant because when they are bred with another morph gene, they create a new mixture of the two.
We tend to use codominace for all of the traits, which is fine for layman terms most of the time but is incorrect for what you're saying.

It is lethal only in a homozygous dominant individual which makes the gene for lethality recessive, but the spider trait itself seems dominant in a heterozygous individual. If the homozygous individual was not lethal, then it would probably look the same since the gene acts dominant; but we don't actually know if it would show a codominant different trait since it's never been achieved.

[OhhWatALoser]

Also, the terms dominant and recessive DO refer to phenotypes. NOT genotypes. That's a common misconception. Therefore, it is perfectly possible for one given phenotypic manifestation of a gene to be dominant while another is recessive. And if you don't believe me, it is even on Wikipedia, the Source of All Knowledge of Everything (okay not really but it IS on Wikipedia):

http://en.wikipedia.org/wiki/Dominan...is_dominant.3F

this is right off the link you posted

"It is critical to understand that dominance is a genotypic relationship between alleles, as manifested in the phenotype. It is unrelated to the nature of the phenotype itself"

[OhhWatALoser]

blackcrystal22

I donno what to tell you everything you are saying seem to conflict 100% with anything i have read on this site or anything to do with genetics on the web. even seem to conflict with the wiki link posted, so i donno what to tell you.