Tarantula Incest?

Bosing

Arachnoangel
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Just to add, I recently got two H. incei sacs from different females that bred with their brother in and out of communal tank captivity. In this case, all tarantulas fed as they wished while in my communal tank set-up. I just dumped a couple of roaches in there and they finish whatever is moving in their area of territory.
 

Poxicator

Arachnobaron
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I think you're getting a little confused by what's possible and what's ethical. Nobody would doubt its possible to mate from the same sac, however by doing so, and likely doing so again we condense the gene pool, perhaps with the result of weaker offspring.

Its hard to prove anything as hobbyists because our experiments and experience is limited. Perhaps my experience of breeding P. regalis last year was an example, (he mated with 3 females, 2 of which were mine, and all resulted in sacs although survival numbers were 5, 10 and 20) but not knowing the history of the male its hard to pinpoint anything. What we do have available is evidence that inbreeding in much of the animal kingdom results in weak stock and abnormalities.
I think you'll find most books covering tarantula breeding, eg The TKG, suggest inbreeding only as a last resort.
 

Introvertebrate

Arachnodemon
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No one's concerned about inbreeding with feeders however. People typically just order their starter colony, and sustain it for there. If heard of mealworm colonies lasting 10 years.
 

JC

Arachnolort
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I mean i dont think i will ever try to breed them just because im pretty sure they came from the same eggsac and the chances of getting 1 of each sex is only a 33.3% chance. which actually are ok odds. Just interested in knowing if it matters
If the species sex quantity is equally distributed, you have the following chances when acquiring 2 of each species:

25% - All male(male,male)
25% - All female(female,female)
50% - Both female and male(female,male or male,female)
 

ZergFront

Arachnoprince
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The male will mature sooner than his female sibling and mating will probably not occur before the male expires. I believe that this is natures way of preventing inbreeding and ensuring genetic diversity.

Ollie
What about a female that double-clutches? ;);P
 

ArachnoYak

Arachnoknight
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I think that there's a little too much anthropomorphising here. The laws of mammals don't apply to invertebrates. I personally don't see anything wrong with breeding sacmates(imho). Evidence of consistent deformities or weakening of the gene pool would have already shown up in some of the more commonly bred species. Keeping in mind that several generations could be produced yearly. That is why they are such good survivors. Sure we see mutations from time to time, but one sling in 400 getting a double abdomen is hardly cause for alarm. As natural mutations occur with great frequency in the natural world.
 
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Spiderman24

Arachnoknight
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Nov 19, 2010
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Also great statement well put mate. I mean like I stated it is very possible to get a sibling of a t you have.
 

Hobo

( ͡° ͜ʖ ͡°)
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Hobo, would you please post a link so I can read about these slings with two abdomins? I ran a search and couldn't find it. I am not doughting you at all, I am just curious.
He's a good thread, with links to various other mutations.


I think that there's a little too much anthropomorphising here. The laws of mammals don't apply to invertebrates. I personally don't see anything wrong with breeding sacmates(imho). Evidence of consistent deformities or weakening of the gene pool would have already shown up in some of the more commonly bred species. Keeping in mind that several generations could be produced yearly. That is why they are such good survivors. Sure we see mutations from time to time, but one sling in 400 getting a double abdomen is hardly cause for alarm. As natural mutations occur with great frequency in the natural world.
Anthropomorphising?
Tarantulas follow the laws of genetics just like any other organism, and genetic defects is certainly not limited to mammals alone.
IMO, thinking tarantulas will magically be "ok" in the long run with generations of inbreeding without culling/natural selection is foolish.
Sure, breeding sacmates may result in seemingly healthy offspring, but continued inbreeding over the course of decades may eventually strongly manifest all hidden "bad genes" of the F2. Like I said, we may be seeing some of those "bad genes" already.

In addition, I do not believe we have been breeding tarantulas long enough to see any significant damage yet, especially with the ones most commonly bred, as they are also typically the ones that regularly get "fresh blood" from the wild through WC imports.

Yes, natural mutations happen in the wild, but unlike captivity, there are many, many things out there waiting to eat something without good survival genes! Only the fittest, and luckiest individuals survive to procreate which alleviates the effects inbreeding. You can be sure that inbreeding happens in the wild as well.

Again, IMO, although you may end up with seemingly perfectly fine spiders from "incest", it would be prudent to avoid it whenever possible, unless you have no choice (breeding a rare, threatened tarantula, for example).
 

crawltech

Arachnoprince
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I dont have much to add to this thread besides whats already been stated....but what i can say is, my current versi sac had a double abdomen sling, and a conjoined abdomen sling....the male and female were not sac mates, nor were they direct desendents of each other.....
 

esotericman

Arachnoknight
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Anyone have any evidence of inbreeding depression in tarantulas? P. murinus has been sib crossed for 3 generations without any measurable problems, and that was in the BTS magazine. Also, it's a huge error to treat all 900+ species the same, M. balfouri and B. vagans would not have the same breeding ecology for example, neither would any arboreals. I do so wish someone would take the time to sibling cross a dozen or so species a few times and check for variations.
 

Poxicator

Arachnobaron
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"Anyone have any evidence of inbreeding depression in tarantulas?"

The problem lies 2 fold IMO.
1. Research on tarantula is in its infancy. We don't have correct ID to many species in the hobby and whole genus are being disputed. Research costs money, so its rather unlikely we'll see papers based on the curiosity or needs of hobbyists. We're far more likely to see papers based on the properties of silk web/venom/urticating hairs etc. Even within these areas the information is likely to be restricted, based on an individual species rather than a comparison of many species.

2. Many hobbyists seem to take a view based on their limited experiences, or the information they find via forums. Many seem content that if issues are not displayed within a short timeframe then the issue is discredited and unfortunately if proof isn't shown they revert to the limited experiences provided by other hobbyists. They are content to continue with their opinions until proved wrong. People consider no signs of issues as proof, whereas issues are often revealed over time/quantity because the issues may not be globally attributed.
To use an analogy its like asking someone how safe a particular city is, the likely reply might be personal experience or hearsay, its not likely to be backed up with statistics.

What I often find amusing is so many people suggest they want to provide the best for their inverts, they want to make them happy, and yet when it comes to breeding they're more likely to seek what's immediately available, discarding the issues of inbreeding and hybridising. Its often quoted that this exists in the wild, as if that's a good measure, whilst not recognising the issues that develop from such natural activities.

So, to find our answers we need to go beyond forums and perhaps attribute scientific reports on related species. Its often the case that inverts that reproduce quickly and have short lifespans make it easier to report findings. There are plenty of sources, but few are free.

Here's a paper worth a read (1997):
Consequences of inbreeding on invertebrate host susceptibility to parasitic infection
Stevens, Lori; Yan, Guiyun; Pray, Leslie A.

"The causes of inbreeding depression are ambiguous, with two major hypotheses being: (1) the overdominance hypothesis, in which homozygosity per se reduces fitness; and (2) the dominance hypothesis, in which the exposure of deleterious recessive alleles causes inbreeding depression. Results from the cSM strain of the flour beetle Tribolium castaneum, the host used in the present study, suggest inbreeding depression is a mix of these two phenomena (Pray et al. 1994; Pray and Goodnight 1995, 1997; Pray 1997). Using the same inbred lineages as the present study, Pray and Goodnight (1995) found inbreeding depression to be genetically variable. Five of seven traits showed inbreeding depression (egg-to-adult viability, female and male relative fitness, female and male adult dry weight); two traits (male and female development time) did not. "
 

esotericman

Arachnoknight
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I agree with most of your post, but drawing conclusions based on species with high dissemination rates like red flour beetles is pretty weak for most tarantulas. Lab cultures are carried on for hundreds of generations, and maybe Drosophila studies might give us a few clues, but again, these organisms are pretty far removed from tarantulas.

I will add that the postage stamp collectors which prevail in the US do not allow for any specialization in a species. Noting inbreeding problems then is impossible within the hobby, but does result in "grab any male you can".

As for falling back on what is "known" in the hobby, most of it comes from mammal examples or reptiles, and honestly if folks want to be careful or even paranoid about inbreeding, I can support that. What I can not support is claims that it's deleterious or a fact inbreeding has negative effects. There is no data.
 

Poxicator

Arachnobaron
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Finding the data is always the issue.
I'd be curious to read more on Stan Schultz claim "In a 1998-January-23 e-mail posting to the arachnid mailing list, Mr. Rick C. West related the results of experiments in inbreeding two species of tarantulas (a Phlogiellus sp. from W. Malaysia and Grammostola iheringi from N. Argentina). In both species, inbreeding caused severe deformities, difficulty molting, and reduced size after only one or two generations. Based on his experiences, we may safely say that inbreeding is to be strictly avoided except in the most extreme circumstances."
 

bloodpythonMA

Arachnosquire
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Jan 20, 2011
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what problem with metallica?
have I missed something?
I hear they have a high mortality rate. Might just be something in the US, as there don't seem to be as many available as over seas. There are tons of factors that could contribute to such things, I was just wondering if that might be a problem with the U.S. population of P. metallica? :?
 

Nerri1029

Chief Cook n Bottlewasher
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Diet?.... so basically he stopped feeding a t so he could mate siblings.... cause its not like you can give him a salad...... he cut back the poor guys food.... but to the guy stating that the male will mature before the female. I do somewhat agree with you except I had a female obt mature two molts before the male. They were fed on the same days as one another. From the same sac. And molted about a week apart. But your theory in the matter makes very good sense
ok?

Using what criteria did you consider this female "mature" ?

I have in my collection (from another breeder) 4 OBT's that are 8th generation inbred. They show no sign of any differences; they exhibit only typical behaviors. I believe this person is collecting the very data being discussed.


ANOTHER thing to consider... in captivity the 'environmental pressures' are different. NO PREDATORS. we might be selecting those specimens who thrive in captivity, i.e. do better with tap water; thrive on low variety in diet etc.

so while "survival genes" may be less prominently selected for, there is a new set of pressures... albeit less threatening.
 
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esotericman

Arachnoknight
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I'd be curious to read more on Stan Schultz claim "In a 1998-January-23 e-mail posting to the arachnid mailing list, Mr. Rick C. West related the results of experiments in inbreeding two species of tarantulas (a Phlogiellus sp. from W. Malaysia and Grammostola iheringi from N. Argentina).
Which list? The archives of the ATS yahoo list are still up, and I believe so are a few others hosted on yahoo.

Since it has not come up since then, I do wonder about the quote though.
 
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