Kind of a good question that came to mind...

[zimbu]

Actually, if you "buy into" evolution any characteristic for which there is a selection pressure for is plausible. Evolution isn't animals running around and mutating randomly and illogically... its a process by which heritable genetics traits become predominant within a population due to differential survival of individual organisms which have varying genetic makeup, and this rate of survival is influenced by both biotic and abiotic environmental factors. Its only illogical if you don't bother spending the time to read and understand the theory behind it.

And what does sudden infant death syndrome being heritable have to do with evolution? Not all heritable mutations are beneficial. Nonbeneficial traits tend to be selected against, which is a possible reason its relatively rare.

A species can either evolve slowly or rapidly depending on the genetic makeup of a population and its size... In a small population with a large number of different alleles present evolution can be measured over the course of generations. In fast breeding animals like insects, species have been documented to evolve noticeably within a few years.

 

[Moltar]

As with any selective breeding and/or genetic engineering program, (I consider them basically the same thing with different technology) There's always the risk of introducing traits unplanned for. Say someone bred two generations of B smithi with longer lived males then began selling slings. Then the slings get bred with many different bloodlines. THEN somebody finds out that there is a recessive gene for small eggsacs or a gene that causes females to be driven to always eat their eggsacs or whatever. Maybe it's mutated spinneretes or delicate abdomens. You'd be 4 generations down the road before it really came to light and probably too late to isolate the suspect T's from the gene pool.

I'm not a breeder myself but i have seen lots of sci-fi movies so that makes me an expert (<-joke). It seems like selective breeding for any trait that is purely for our benefit and not the bloodline's is asking for trouble. These aren't like dogs where all species are domesticated. Since there are so many species in this hobby that are endangered in the wild we should strive to insure that the bloodlines remain as unsullied as possible.

I know this was just a hypothetical "what if" kind of question but this is what i thought of when i saw the thread.

 

[xBurntBytheSunx]

"Actually, if you "buy into" evolution any characteristic for which there is a selection pressure for is plausible."

certainly any would be plausible but species have many characteristics for which there is no "selection pressure" for.

"Its only illogical if you don't bother spending the time to read and understand the theory behind it."

I'm assuming this is an insult ;P I think if you take a hard objective look at the theory you will find "problems" or things that aren't always "logical." I'm not arguing species never alter characteristics. I'm just saying if animals evolve the process is not always logical.

"And what does sudden infant death syndrome being heritable have to do with evolution? Not all heritable mutations are beneficial. Nonbeneficial traits tend to be selected against, which is a possible reason its relatively rare."

if species tend to select charactaristics that promote the species SIDS shouldn't exist. I think the key word here is non-beneficial traits "tend" to be selected against. but often times they are not. so therefor, it would not be logical for male tarantulas to live longer, but the possibility could exist b/c of mutation or selection of a non-beneficial characteristic.

 

[zimbu]

Obviously species select for characteristics which promote the species. But unless SIDS manifests in 100% of the offsping of an affected parents the gene will still be passed on and never completely removed from a population.

Also, the process is never going to be 100% logical because species don't decide how they are going to evolve, but they WILL evolve in reaction to whatever environmental factors are causing differential survival. So there is a certain logic behind it a large part of the time, it just isn't always going to end up being the best solution for a species as a whole in the long run. Then again, because of random genetic mutation it is always possible for a completely random trait that doesn't help a species in the slightest to appear and be passed on to progeny.

Species may ahve characteristics for which there isn't a SPECIFIC selection pressure, that's true. I mean, and easy example is spiders having 8 legs. Why 8? Why not 6 like insects? Why not more like crustaceans? There probably IS no specific reason. But like I said, evolution isn't entirely logical and doesn't have to be to still make sense as a theory. It is entirely possible, and likely, that as both insects and arachnids moved onto land, a reduction in number of legs was for some reason beneficial to their lifestyle. I'm not even going to speculate as to why, because this thread was originally speculating about an entirely different characteristic of tarantulas.

Anyway,what I was saying was that there is probably no reason spiders have 8 legs specifically, but I'll bet that there was selection pressure which lead to a reduced number of legs compared to ancestral athropods.

If you wanna continue argueing about evolution maybe we should start a specific thread, because this thread is getting seriously hijacked.

 

[xBurntBytheSunx]

i'm not arguing about evolution, i'm simply saying there is no reason, even evolutionary based, why a species shouldn't develop a trait that isn't necessarily beneficial.

 

[Stylopidae]

i'm not arguing about evolution, i'm simply saying there is no reason, even evolutionary based, why a species shouldn't develop a trait that isn't necessarily beneficial.

My last post is one suggestion about why males have a short lifespan, zimbu's post is another.

pretty sure it is possible. you can manipulate just about any characteristic via selective breeding.

and if you could do it to a few species there would be a DEFINITE market for it... pampho's, P. cancerides, some of the A's and B's.... mmmmm nice.

How would you propose we do this?

As I said, there's no way to tell how long a male will live until the day it dies.

If anything, captive breeding will do this by itself. The males which remain virile longer will be able to breed with more females and produce more offspring. Maybe in a few hundred years after the species we have in the hobby now have been cut off from wild populations for awhile, males will be around longer but I don't really think there's a way for us to intentionally breed this specific trait.

 

[Drachenjager]

someone mentioned that maybe its not that males ahve short lifespans but that females have exceptionaly long ones. And i tend to agree with that. It seems for some reason female Ts even male Ts live longer than the true spiders. Take the argiope in my garden. She will mate and make an eggsac, (which she has done already ) and later she may lay another but she is on her last leg now. she wont live any longer and the male ...well he is dead already and turned into a bolus. But he was this years sling and she was too... If Ts lasted as short of a time as the argiopes we wouldnt be having this discussion at all would we? SO maybe they have just devoloped long lives in particular and the males still follow general spider habits by not living long after thier maturing molt , it just takes them longer to mature.

 

[zimbu]

Yeah exactly Drachen, that's what made sense to me. And I think Cheshire was right when he was saying we would have to look into relative lifespans among the other primitive spider groups, especially the common ancestor of both aranaeomorphs and mygalamorphs.

Another thing I was thinking that might be useful to look into was any possible differences in lifestyle between female tarantulas and other spiders. If they did evolve to live longer, there has to be a reason, and it might have to do with the fact that they spend most of their time hiding, and thus are not often exposed to predators. If they don't often die due to predation then a longer lifespan would indeed be advantageous because more males (who ARE often eaten by predators, and thus have no reason to live longer) will find them during their lifespan.

Of course, if other groups of spiders show similar mating habits where the female hides and the male searches, but does not show similar differences in lifespans, then maybe we should be looking at other possible reasons as to why the difference exists.

Anyone who knows way more about spiders then me care to contribute?

 

[cacoseraph]

My last post is one suggestion about why males have a short lifespan, zimbu's post is another.



How would you propose we do this?

As I said, there's no way to tell how long a male will live until the day it dies.

If anything, captive breeding will do this by itself. The males which remain virile longer will be able to breed with more females and produce more offspring. Maybe in a few hundred years after the species we have in the hobby now have been cut off from wild populations for awhile, males will be around longer but I don't really think there's a way for us to intentionally breed this specific trait.

acheta domestica feeder crix were bred counter to this... but basically only the fastest breeders (quickest to mature, shortest gestation) were allowed to breed.... and of that set of offspring the fastest were allowed to breed... and of that set of offspring the fastest were allowed to breed... and of *that* set....

so you could do the exact opposite of that. powergrow all your males... and only take the ones that take more than a certain amount of time to mature to breed. wash, rince, repeat. from what i have gathered with Dr. Bustard's giant T. blondi experiments it takes 2-4 generations, cleverly bred, to start manifesting reliable differences compared to a sort of breed "baseline". you can even do a sort of generation compression since the males would mature faster than the females to super line breed. that should lock some traits in there =P i expect you would have to cull anything that started to manifest too bad of other concentrated traits, though. is how dogs and cats work. or sterilized, at least

 

[zimbu]

Couldn't you run into problems with that by accidentally selecting for animals that have smaller appetites and therefore eat less and grow more slowly though?

Although I guess they still have longer lifespans, even if it is as a result of something else...

Then again, who knows if appetite is even heritable.

 

[Quizzler]

i think if you buy into evolution any possible charactaristic is plausible.

do species evolve slowly over eons or do they mutate rapidly? i think there are proponents for both and arguements against both theories.

why does the duck-billed platypus have a bill? this doesn't make sense. why is sudden infant death syndrome inheritable? this doesn't help our species survive.

according to the theory i don't think there is any reason for male spiders to live longer but i also don't think there is anything standing in their way. it wouldn't make sense if they did live longer but then again i don't think evolution has to have any logic to it.

SIDS is inheritable only as a recessive gene, only when two parents who both have the recessive gene is there a chance for it to happen, it's not passed on by the children because they die (duh), It wasn't passed on as a benefit but as a mutation of genes among humans that happened among us for whatever reason. Let's say A's genetic structure was slightly altered at birth from any of the various ways it can be changed, they're perfectly healthy, but they still carry it. Then when A mates with B and B also has a recessive gene it can be passed on and that infant will die. But if A and B have a kid who is heterozygous dominant then he is still going to carry the disease, that's how SIDS is passed on, it's not an evolutionary advantage, but a recessive genetic disorder.

 

[cacoseraph]

also, from my very weak understanding of all things genetic, there are like, complexes of genes that sort of get stuck together... so somethign that is highly beneficial could come with a price that is neutral or negative

one example is that there is a theory that for humans there is complex that gives high intelligence... and depression and emotional instability... but it is like, inheritable as a unit, for whatever reason


i am very seriously considering goign the opposite route and making lightning obts that have males that can reach maturity in 4 months. i think it would be fun to tune them down so tightly

 

[julesaussies]

or basically are we stuck with them living no longer than like 3-5 years or less??

Actually, i don't think this would be a good thing. You know how many people are looking for male B. smithi's right now?? They mature a lot slower than many other T's. i would guess that the mortality rate of slings in the wild must be astronomical. Since males are designed to basically only live up to maturity - i think it was greatly reduce the opportunities for breeding, even in the wild. i have absolutely no facts what so ever, just thinking outloud...

 

[demicheru]

SIDS is inheritable only as a recessive gene, only when two parents who both have the recessive gene is there a chance for it to happen, it's not passed on by the children because they die (duh), It wasn't passed on as a benefit but as a mutation of genes among humans that happened among us for whatever reason. Let's say A's genetic structure was slightly altered at birth from any of the various ways it can be changed, they're perfectly healthy, but they still carry it. Then when A mates with B and B also has a recessive gene it can be passed on and that infant will die. But if A and B have a kid who is heterozygous dominant then he is still going to carry the disease, that's how SIDS is passed on, it's not an evolutionary advantage, but a recessive genetic disorder.

I'm fairly certain that SIDS is *not* a genetic condition. I've never read that the condition is, but an associated arrhythmia is. A coworkers wife is a pediatrician, and has done with with SIDS. There has also been a number of studies showing that laying your baby FACE UP instead of FACE DOWN enormously cuts the incidence of SIDS.

Also, a platypus has a bill because it is a useful tool for sweeping up the type of aquatic plants it eats.

I think the argument that selective breeding should be avoided because you might accidentally selectively breed a negative trait alongside a desired trait is sort of silly. I don't think there is any statistically significant difference in the chances of that happening with selective breeding vs non-selective, random breeding. Incidences of this happening, especially in dogs and cats, are more likely attributable to line-breeding than selective breeding.

Evolution is a process that is accepted by pretty much every credible scientific body at the present time. There might be many aspect of evolution that appear "illogical" to you, and there might be things where we can't really point out and say "this is the specific environmental cue that dictates this particular selection", but that doesn't in any way mean that it doesn't exist. Absence of proof is not proof of absence.

All that being said, I have to agree with pretty much everyone else - there doesn't seem to be any drive for males to live longer than they currently do. They are existing in more or less the same environment they have lived in for thousands of years, so there is no real change in environmental variables that would cause such a significant gear-shift for them.
The only thing I can think of would be if their maturation was dependent more on some sort of hormonal/physiological time scale than a regular chronological scale. If there is a required buildup of some chemical or stimulus for the various stages of growth, and something in our environment (say continued global warming, massive overuse of pesticides and herbicides, continued deforestation - where are all the freaking BEES, by the way) and this upsets the availability of those required stimuli, it might take them longer to reach whatever action potential or "activation energy" and then each stage would last longer. I don't think this would cause mature males to live any longer, except perhaps a matter of a few months.

i'm not arguing about evolution, i'm simply saying there is no reason, even evolutionary based, why a species shouldn't develop a trait that isn't necessarily beneficial.

This is another thing people often use to argue against evolution. But its just a gross oversimplification of the process. It's not a checklist that just says "yes, giraffes with longer necks work better, so we'll keep those ones and get rid of the rest". It doesn't require that every single expressed trait be directly advantageous. Organisms that possess traits that make them better suited for their environment tend to have better chances of reproduction. It doesn't say that only those traits that made them better suited are passed down. If my kid was immune to all known diseases and also happened to have 11 fingers, then he/she would certainly have a significant evolutionary advantage, and the 11 fingers would be passed along as well (obviously, not necessarily expressed). You could also have someone with 11 fingers who is not really above average for environmental suitability, but because they are at least somewhat well-suited for their environment, and because we humans have to a large degree subsumed natural selection to artificial selection through modern medicine, he/she would still stand a good chance of reproducing and passing along the 11th finger.

 

[Stylopidae]

I'm fairly certain that SIDS is *not* a genetic condition. I've never read that the condition is, but an associated arrhythmia is. A coworkers wife is a pediatrician, and has done with with SIDS. There has also been a number of studies showing that laying your baby FACE UP instead of FACE DOWN enormously cuts the incidence of SIDS.

Also, a platypus has a bill because it is a useful tool for sweeping up the type of aquatic plants it eats.

I'll definitely be back to this later, but there are two things I must cover right away.

1.) There are actually some genetic correlations for SIDS, which I'll cover later tonight.

2.) The platypus's bill is actually a very acute sensory organ which helps it locate the prey it eats in muddy water. The platypus is NOT a herbivore.

 

[zimbu]

Neat...exactly what kind of sensory organ is it? Is it similar to sharks detecting electrical fields with their ampullae of Lorenzini (sp)? Or am I totally off base?

I never knew it was a sensory organ, that's really cool. Do they also rely on the bill to find buried prey or is it more of an adaptation to murky water/poor eyesight?

 

[cacoseraph]

Neat...exactly what kind of sensory organ is it? Is it similar to sharks detecting electrical fields with their ampullae of Lorenzini (sp)? Or am I totally off base?

I never knew it was a sensory organ, that's really cool. Do they also rely on the bill to find buried prey or is it more of an adaptation to murky water/poor eyesight?

i think it is mainly tactoelectric sensor. range very short. for eating bugs and small verts out of the mud and stuff

 

[xBurntBytheSunx]

once again, not arguing against evolution. i just think that if species do evolve there is no reason for them to not develop "random traits" with no biological benefit. that is my only point.

maybe duck billed platypus is not the best example for what i was saying. but i think a lot of species have traits that don't exactly help the species advance. after all don't humans have an internal organ that serves no purpose? i'm not sure the name of it off the top of my head.

"Evolution is a process that is accepted by pretty much every credible scientific body at the present time."

thats fine for them, and like i say i'm not arguing against it here. however i do not believe species have evolved in the way we are taught. there are simply too many assumtions for me. like we have been taught dinsours evolved into birds because of similar bone structures. here is an assumption. i read scientists recently discovered bones of a bird 26 feet long which they say will change this idea that dinosours evolved into birds. i think there are a lot of things we just simply don't and can't know.

and once again i'm not arguing against evolution. though i do admit i don't believe in evolution and i hope you can accept that. and i'm not knocking anybody that does either.

 

[rattler420]

the thing people often forget though is that science in itself is not fact. its only our best guesses until proven wrong.

 

[Drachenjager]

... but that doesn't in any way mean that it doesn't exist. Absence of proof is not proof of absence.

yeah, but if someone who believes in God says it to an athiest, it is scoffed at lol i guess its only true if you are backing evolution.