An Hypothesis - True or False

[Mark Newton]

Does fecundity increase the lifespan of an adult female scorpion? In other words, if an adult female scorpion fails to mate and become gravid does her chances of an early death increase? This doesn't mean she dies a virgin, it means even after multiple parturitions, does mating increase survivability?

 

[emmille]

ok

probably, i didn't think about that....hmmmmm...

 

[Rigelus]

does mating increase survivability?

Having just had a quick check through "The Biology of Scorpions" and without being able to find any other references relating to this hypothesis my off the top of head answer would be no, it doesn't.

Sure, mating will increase the survival rate of a species (common sense!) but for an individual i would have thought that the stress of regular parturition would "wear" the females body down.

My wife is very much into praying mantids (to short lived for me) and it's apparently common knowledge (say's the missus) that an unmated female lives longer than a mated one. She once had a unmated female Phyllocrania paradoxa live for almost 14 months as an adult whereas the normal life expectancy for a mated female is in the region of 8-11 months.

Interesting question though and i'd be interested to hear if anyone else has a more definitive answer on the subject.

 

[sick4x4]

yeah im going with no either....besides i don't really think there is a mating clause when it comes to reproduction or the lack there of....sooo with that being said , as long as the protocols are met such as food, heat and the ideal environment are matched...a longer life can be fulfilled...but just because you don't mate out a female doesnt mean a shorter life is expected. though a great question....i just don't think there is enough research on the topic to really conclude a definite answer

 

[Thaedion]

I would only be guessing, but since a scorpion has a "life span" and it lives within this span whether mated or not the act of mating neither helped or hindered it's survival. but say you have litter mates and take one and mate her as much as possible, take the other and keep her secluded from a mate. see who lives longer.

 

[Rigelus]

take one and mate her as much as possible, take the other and keep her secluded from a mate. see who lives longer.

One wouldn't be enough..
If your unmated female did indeed live longer would it be because she hadn't been mated or because she had a better genetic disposition...!

You'd have to have many pairs of the same species. Temp and humidity would have to be identical in all enclosures as would the feeding regime.
You would then be able to reach a statistical probability for or against the hypothesis

 

[Mark Newton]

The reason I asked this question was because more than once now I have had WC females die some time after parturition if they have failed to mate post parturition. It does seem odd that a lack of mating might increase the chances of death, but scorpions arent exactly model organisms.

I wonder if its possible that females that fail to successfully mate have increased susceptibility to death as a mechanism to increase resources available to those with a higher fertility rate. The species I have experienced this with are solitary rock dwellers that are very aggressive and will defend their rock space to the nth degree, they have zero tolerance on anything entering it. This is because real estate is a major issue with some rock dwelling species, in fact the number of suitable rocks would have a large influence on population size and structure. A female that has low fecundity would be a burden to the species as she is taking up rock space that could be utilised by a more fertile female. Any thoughts...

 

[Rigelus]

It does seem odd that a lack of mating might increase the chances of death

Oh, i see, you're not wondering if a lack of mating increases survival rate but rather whether it decreases survival rate...(thats what you get using all those big words ;-)

A female that has low fecundity would be a burden to the species as she is taking up rock space that could be utilised by a more fertile female

That makes sense when taken at face value however why do we not then see other animals whose lifestyle creates a need for a particular resource that is not abundant do the same.
Also why should nature allow weak females to die. Why stop there...what about all the other unperfect specimens who are taking up space..

Natures usual method is that one creatures death is another creatures sustenance together with the survival of the fittest.
Your hypothesis would mean nature is intervening with her own rules..

 

[skinheaddave]

I have had WC females die some time after parturition if they have failed to mate post parturition.

Did these females fail to mate for absence of a male or by refusal? It seems to me more likely that fecundity decreases with age after a certain point. If fecundity and survival are, indeed, correlated, the most likely causation is that old age causes reduced fecundity.

Cheers,
Dave

 

[Mark Newton]

Did these females fail to mate for absence of a male or by refusal?

Absence

It seems to me more likely that fecundity decreases with age after a certain point. If fecundity and survival are, indeed, correlated, the most likely causation is that old age causes reduced fecundity.

Very true...and what I would expect too. Female scorpions can only have so many broods until they run out of oocytes. What I need to do is look for diverticula that have not been fertilised to get an idea of how many matings might have been left in the scorpions life.

Certainly not saying my hypothesis is true or false at this stage, just a thought, seems a little too coincidental.

 

[H. cyaneus]

What I need to do is look for diverticula that have not been fertilised to get an idea of how many matings might have been left in the scorpions life.

Get a fast growing species, get a few broods from several adult females. Raise the young, then breed those females until they stop breeding or get eaten/die for unkown reasons.

Since over is Oz you have some slow growing species, someone from the American or European hobby could do it. Just get some C. gracilis or something similar.

I think that the amount of broods a female could have will differ from species to species. I remember reading that T. serrulatus can only have 5 broods then they stop reproducing. But they still live.

You could to the experiment to see how long the females will live if they are constantly bred, or don't get any action. It won't be hard, but it will take several years to get any good data.

Mike

 

[Bayushi]

I think that the amount of broods a female could have will differ from species to species. I remember reading that T. serrulatus can only have 5 broods then they stop reproducing. But they still live.

yeah but they are parthenogenic, so you don't actually have to mate them.

 

[H. cyaneus]

The only thing different is that the female doesn't get dragged around to the spermatphore. The parthenogenic process just seems time consuming, not very hard/painful.

Mike

 

[EAD063]

I wonder if its possible that females that fail to successfully mate have increased susceptibility to death as a mechanism to increase resources available to those with a higher fertility rate. ......... A female that has low fecundity would be a burden to the species as she is taking up rock space that could be utilised by a more fertile female. Any thoughts...

When I read the thread this morning, this is what had first struck my mind. I would say that is definently a plausable theory, especially with such an old class of organisms.

Natures usual method is that one creatures death is another creatures sustenance together with the survival of the fittest.
Your hypothesis would mean nature is intervening with her own rules..

Rigelus,

I'd like to argue those are our rules of nature rather than it's own, but eitherway survival of the fittest is more of an evolutional theory than being said in regards to a specific specimen, I do not believe that application fits in this discussion. What does fit in my opinion is the basic strategy that organisms live by, which is survive, reproduce, die. From a species standpoint, even humans if you think about it, our only true purpose as individuals is to reproduce.

Have a good day all
Ed

 

[skinheaddave]

What I need to do is look for diverticula that have not been fertilised to get an idea of how many matings might have been left in the scorpions life.

A better first step may be simply to confirm the correlation. How many females of that species have you had go through your care? If you add up the numbers in each potential category (died w/o any event, died post parturition, parturition followed by mating etc.) then you may be able to find out whether there is an effect at all.

Cheers,
Dave

 

[kahoy]

the male goes insane and stabs the female...