Inbreeding

Reitz

Arachnobaron
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Is inbreeding problematic with scorpions? It would seem that, since they're genetic structure is so much more simple than that of mammals, inbreeding wouldn't really have a negative effect, but is this correct?

Chris
 

Malhavoc's

Arachnoking
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I dont think there genetic structure is anymore simpler then ours different yes.. simpler I question Inbreeding would probably result in sterility and deformations
 

chau0046

Arachnobaron
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Interesting question,

This subject has come up a couple of times in the past concerning the ability to start a colony on just a few individuals. There isn`t anything ,to my knowledge, writen saying so... But i beleive it would have to have some sort of negative effect, maybe infertile scorps. But like Dave said " it would just make good scorp food if you have duds.:)"Lol. The subject came up on the same broods of C. gracilis` that you and me have had . Maybe we could trade on the next batch to keep the gene pool from getting too shallow.

Take care Chris,

Mat
 

Reitz

Arachnobaron
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That's a good point, Mat, I sold off all but two, both of whom are now in their 6th instar.

I still feel like there wouldn't be a problem. Here's my logic: Some scorpions are parthenagetic (spelling), meaning that they get the EXACT same genes--not one iota of difference. It would seem that if this is possible, inbreeding wouldn't be any worse. Now, granted, I am thinking about the C. gracilis, which do have to mate in order to reproduce, however, they're not any more complicated genetically than any other scorp, including the parthenagetic ones.

Make sense to anyone else, or is my ignorance of how genetics really works painfully obvious?

Chris
 

chau0046

Arachnobaron
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Good point Chris,

Guess someone will have to try ...


Mat
 

biznacho

Arachnosquire
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If I remember my high school biology class correctly, some bit of genetic material do get mixed around durring any sort of reproduction. So it is possible to have the exact same DNA as a parent, just in a differnt order along the chain. I could be wrong(read as probably). I was never all that great at biology, I barely got a C-.

biznacho
 

Eurypterid

Arachnerd
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Eeeeek! Genetics teacher nightmares! First, parthenogenesis is not the same as inbreeding. There are a number of ways in which it can occur, and I'm not sure about exactly how parthenogenetic scorps do it, but it's probably more like cloning (which is not the same as inbreeding at all from a genetic point of view).

The problem with inbreeding is this: in most natural populations, each individual will carry numerous defective single copies of genes. However, each defective form is very rare in the population, e.g., even though any one individual has several, the ones he has are unlikely to be the same ones found in any other individual in the population, unless the two are very closely related. These defective gene copies don't normally show, because the other copy that the individuals have is normal and good, and covers the presence of the defective copy (In most animals, each individual has 2 copies (called "alleles") of each gene, so there are three possible combinations: 2 good copies, 1 good and 1 defective, or 2 defective copies. For most defective gene copies, you must have two defective copies in order to have a genetic disorder). However, even if a defective copy is extremely rare, since closely related individuals are much more likely to share the same rare gene copy than unrelated individuals, a mating between them is drastically more likely to produce offspring that have both copies of the same gene be defective.

For example, let's say that you have two scorps and one of them carries one defective copy of one single gene (an extremely low incidence, by the way). Let's say that this defective form is extremely rare - your scorp is the only one of his species that carries it, and he only has one copy. You mate him to the female who has two good copies of this gene. There is zero chance that any of their offspring will have 2 defective copies, because even if they get the defective copy from the father (a 50% chance), there is no chance of getting it from their mother (because both her copies are good). So they are all physically normal, but each has a 50% chance of having got the one defective copy from their father instead of his good copy.

So, let's say you then cross two of these offspring together to produce the next generation. There is a 50% chance of having the defective gene copy for each scorp, so the chance that both of them have one defective copy is 1/2 x 1/2 = 1/4 (25% chance). And if they both do have defective copies, there is a 50% chance for each scorp that they pass it to each one of their offspring, which means that the chance that they both would do this is also 1/2 x 1/2 = 1/4. So, all together, if you cross two of these siblings, there is a 1/4 (the chance that they both have a defective copy) x 1/4 (the chance that they both pass on the defective copy if they have it) = 1/16 (6.25%) chance for each of their offspring that they will get 2 defective copies and have a genetic disorder. Compare this to essentially a 0% chance if they were mated with unrelated scorps.

6.25% may not sound like much, but if you had 32 offspring, on average 2 would suffer the defect. Then multiply that by however many other genes for which one of the original parents had even one defective copy, and you can see how sib-sib matings can lead to very rare genetic defects showing up in large percentages.

On the other hand, if scorp parthenogenesis is essentially cloning, even if the parent has many genes for which it carries single defective copies, it won't have any offspring that have 2 defective copies of the same gene. Instead, they will all be genetically identical to their mother, and only carry single defective copies. Besides, the fact that some species may reproduce this way cannot be used to understand anything about genetic effects of inbreeding in species that don't. It's apples and oranges.

The short version is that, assuming scorps are like most other sexually reproducing species, severe inbreeding (like sib-sib mating, or parent-offspring mating), even for a single generation, has a high likelihood of producing a greatly increased percentage of individuals with genetic disorders, including lethal genetic combinations.

Good questions, but I wouldn't try it.
 
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Silver.x

Arachnoangel
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re

All in all, just keep the inbreeding to a minimum or you'll get some defective and possibly mutated scorpions.
 

krtrman

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i believe that with parthenogenic (spelling?) species they do get the same genes but it is the arrangement of these genes that makes them a different critter altogether. since the egg has no sperm to fertilize it some temp change or a chemical signal has to do that. thus the egg draws on its own genetic material to complete the stages of growth. this is by no means an ideal situation but a last resort effort. some lower forms like aphids do this when no mate can be found past a certain portion of the mating season. it seems that most parthenogenic offspring tend to be male at least with bees ants and aphids and some small fish. and some of these males have turned out to be sterile or die quite quickly without having mated. natures way of keeping things diverse. life has a wonderful way of turning something simple into a huricane of complexity. someone please corect me if any of this info is wrong.
 
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Reitz

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Thanks everyone, esp. Eurypterid, I'm sure you make a great teacher! I was kind of hoping that scorpion genetics would be somehow simpler than more evolved animals--but no luck I guess.

The problem for me is two fold. First, I want to keep all my C. gracilis together, but they're all related, so how can I prevent them from mating?

Second, I want to breed again, and can't find a male!

Chris
 

Eurypterid

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No problem Chris. I actually enjoy teaching topics in biology. That's why I do it. And one of the things I love about people that keep "unusual" pets is that they are usually actually interested in the biology of their animals.

If they just happen to mate because they are in a communal tank, I wouldn't worry too much about it. You'll get mostly inferior quality animals, but they'll feed the others. But if you want to intentionally breed scorps and want the offspring, then you need to introduce some genetic variation and keep inbreeding to a minimum. Maybe remove females until they have mated with a known-unrelated male, and then remove them again after they give birth, in order to prevent an unwanted mating.

That is, unless you you are trying for a specific morph or something, and don't mind working on it for several generations. If that's the case, PM me, and I'll give you some advice on how to accomplish that. You'll have to accept that most of the offspring in each mating (maybe all sometimes) will be write-offs though.

As far as parthenogenesis, like I said, there are many different ways in which this can occur that can be very different from each other. It's not just one process. It's completely different things in different species. We just use the same term to refer to it since in each case the result is offspring from an unmated female. In some organisms it is only an option, usually excercised under particular environmental conditions, or in the case of the insects in the order hymenoptera (ants, bees, wasps), in order to produce males (and in this case it is very different from most other organisms, in that males only carry half the number of gene copies that females do). Other organisms reproduce only parthenogenetically. In either case, it usually does not produce inferior offspring, and in the species that only reproduce by parthenogenesis, the offspring are all females (otherwise there would be no next generation).

Also, as far as the genes rearranging themselves during the process, that depends what you mean. In some forms of parthenogenesis (but not all), they may undergo recombination, which is when two copies of the same gene switch places (a process that also occurs during the normal formation of eggs and sperm in all sexually reproducing organisms), but each gene usually retains its position in relation to all the others. Unless this happens though, the offspring will be genetically identical to the mother. Also, in species that only reproduce parthenogenetically, even with recombination the offspring will be identical to the mother, because the mothers have no variation in their genes. The reason why would take a whole post as long as this one to explain, so I won't go into it. But unless a species frequently switches between the two modes of reproduction, parthenogenesis will usually produce offspring virtually, if not completely, genetically identical to the mother, and they will not run the same risks of genetic defects that inbreeding causes.

For anyone really interested in this stuff, try to find a book on Population Genetics. Unfortunately I don't know of any decent ones for the layman, and to really understand how it all works requires a pretty decent working knowledge of statistics. But if you're up for a challenge, I think it's one of the most interesting disciplines in biology.

Gary
 
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AK47

Arachnosquire
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Bad Idea

Against the Holy Bible!!! Your scorpions will go to h_ll !;P
 
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