Reptile & Amphibian Forums

What will i get if i bred a spider to a spider?
What hatches will be 100% spider, i already know!
But....will this hatchlings be a "homozygous" Spider? Wich means, if I bread them to a wildtype ball, i will get 100% spiders, too??
Are all dominant traits like this?

Sorry the photo has nothing to do with the tread!
....too fast fingers on board!

spider to spider will give you all spiders.

That was not the question!
I already know that!

Spider to spider would give you 75% spiders and 25% normals. If spider genetics behaved like a classical dominant gene, theoretically 1/3 of the spiders produced in the clutch would be homozygous and therefore if they were bred to normals they would produce 100% spiders. However, I do not believe that spider genetics have been completely determined yet. In fact based on the fact that to my knowlege there have not been any spiders bred to date that will through 100% spider clutches, it seems likely that there is a different genetic phenomenon which explains the phenotypic expression for spider.
Grant

Is this a fact for all dominant traits or only for the spider??
I mean, if i bred a granite to a granite, will it be the same?
Or has no one already done this?

I am not familiar with the genetics of the granite trait. In the case of "classical dominant" traits, homozygous and heterozygous animals would be phenotypically identical (express the trait)but 100% of the offspring from the homozygous animal would express the trait, whereas only 50% of the offspring of the heterozygous animal would express the trait.
In the case of spiders it is my understanding that of the few spider to spider breedings, there have not as yet been any documented cases of offspring that throw 100% spiders. For this reason it is suspected that some other "non-classical" genetic explanation. Genetics "outside of sweet peas" does not usually function according to classical mendelein genetic patterns. Vertebrate genetics is much more diverse and complicated.
Good Luck
Grant

Thanks Grant

75% spiders & 25% normals
see post below

As I understand it the issue of whether the morph is dominant or not doesn't matter; the problem is that dual spider genes are not viable for life so that it never makes it past conception. For example every spider now has these genetics:

S = spider gene n = normal gene

existing spiders are all "Sn"
a spider with the genetics "SS" will never make it to birth

this would lead me to believe that a spider to spider breeding would give you 2/3 spiders and 1/3 normals.

P.S. All this information is just a guess, oddly enough nobody seems to want to fund a gene mapping program for ball pythons...... Just Wierd!

It is possible that the homozygous spider genotype could be lethal and have heard this hypothesis previously. This could be the case, but I do not believe it has been proven. Equally likely is one of many other non-classical genetic explanations.
I have actually looked into the possibility of gene mapping and have some experience. I even went so far as to identify equipment etc. However, I would just say that it is not as easy as many think and takes considerable time even with the powerful DNA sequencing machines available today.

So we can say, now we know nothing more than:

Spider X Spider = 75% Spider
Spider X Wildtype = 50% Spider

But it would be interesting what the guys think, wich are the big ones in this buisness!

Hmm, and here I thought spiders were a Co-Dom trait like Pastels....oh well not the first time I am wrong in my thinking, very interesting read.

I am not surprised to hear that Spider x Spider may result in a 'lethal' combination. Many spiders have that head wobbling trait which may be the lethal gene in it's het form. But then again I am just guessing here. I can't even afford a single spider much less the time and space to do a serious breeding experiment to find out how often spider x spider produce normal or otherwise, non spider offspring or if the wobbling head common to many spiders, is related to the lethal genes etc.

Gene sequencing is no easy task, they have only recently mapped the human genome and that took what, 20 years? and that is just mapping it, figuring out what all the pairings do and affect, is still on going. Though snakes are a bit less complicated with, I think, fewer chromosomes, (then again, maybe they have more, seems most animal life have more than the human numbers), it will take a long time to really isolate what chromosomes and genes affect color and pattern, much less what mutant genes can be lethal etc.
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PHLdyPayne