That's No Leaf — It's A Spider!

a reply to: imitator

I'll cancel my internet and donate all my elecronics before watching that video.

A tree full of spiders. Are you being anti agoraphobic?
I'm sure others will enjoy it in a way that will confuse me for a very long time

a reply to: theantediluvian


Its yours! I dont need to be reminded of that spawn of satan!

a reply to: Greggers

originally posted by: Greggers
PhotonEffect: First of all, you're being far too literal here.

Really? Was it the bit about it taking millions of years and many incremental accidental mutations to get to a leaf like phenotype?

originally posted by: Greggers
Are you suggesting the mutational hotspots are not based on "genetic propensity?"

I'm not aware of that term

If you're referring to the probabilities of advantageous mutations occurring, then mutational hotspots would suggest the opposite of these being "accidents". These hotspots show higher "propensities" for the same types of mutations – ones with functional and morphological importance. Some are also reported to occur and be conserved across different taxa. So then - what's the probability that the same "accidents" keep happening to the same gene(s) in unrelated species?

There's a case I read recently where separate populations of the same species of hummingbirds evolved the same traits due to analogous genes mutating the exact same way (i.e. the same targeted amino acid changes). IOW the traits didn't propagate through the population from a single source genome/mutation, they evolved in parallel almost identically. The genetic implications of this are striking.

originally posted by: Greggers
A perfect adaptation such as this where an animal is able to accurately replicate its environment is very unlikely to have occurred as the result of a single mutation. Sure, it's possible. That would be pretty damned incredible though.

I'm sorry but why is this "very unlikely" to occur?

originally posted by: Greggers
Are you suggesting that this particular species developed via some manner other than speciation via natural selection?

I adhere to a position along the lines of Gould and Lewontin on this matter. Aside from that, I'm suggesting that a deeper study of this species, and its underlying genome, is required before any reasonable conclusion about how it actually evolved can be made.

a reply to: Arbitrageur

originally posted by: Arbitrageur
It doesn't seem like a stretch to say this is how natural selection works and we have plenty of evidence that's how it works in other species so it seems likely the same thing happened here.

I don't take issue with the explanation of natural selection here, just the blind application of it. I understand that to you and many others it doesn't seem like a stretch because conventional wisdom has permitted this leap of logic without having to do actual scientific analysis about the species' life cycle or genetic history. Really, all anyone has to do to conclude natural selection is pick a trait (any trait) then decide that it confers fitness or is adaptive regardless of whether it actually does/is. That's not science as far as I'm aware

This "plenty of evidence" you speak of exists mostly in the lab using the same computer models and the same model species. Far less research in nature though, where the dynamics are much different.

originally posted by: Arbitrageur
But if you are a little less pedantic you can acknowledge that if you've seen natural selection in thousands of other species, it wouldn't be a shocker to suspect it was also at work in a species you just discovered.

Have we really observed it "in action in thousands of species, or perhaps thousands of times in the same few model species and simulations?

Beneficial genetic mutations do not have to take millions of years.

The point of the Darwin theory is that specific species become the predominant species through natural selection etc etc.

Genetic mutation happens on micro and macro levels during an organisms life, and then happens again with conception of the next generation. There is no doubt things mutate, but for a species to become predominant it takes natural selection.

Flying spiders that spit acid could mutate tomorrow. That specific part doesn't always take 'millions of years'.

originally posted by: PhotonEffect

originally posted by: Greggers
PhotonEffect: First of all, you're being far too literal here.

Really? Was it the bit about it taking millions of years and many incremental accidental mutations to get to a leaf like phenotype?

It was the bit about suggesting that's definitely how it happened in this particular case, instead of how it has happened in millions of other cases and COULD have happened in this case.

Again, keep in mind, the purpose of my statement was to counteract the notion that there is something supernatural or unexplainable about adaptations such as these.

originally posted by: Greggers
These hotspots show higher "propensities" for the same types of mutations

Exactly. Just to be clear, there is NO SUCH THING AS PURE RANDOMNESS in classical physics, nor in biology. Genetic propensity is simply a way of saying that the unknown factors that influence how the dice roll are based upon the creatures existing biological composition.

originally posted by: Greggers
I'm sorry but this is very unlikely to occur "why"?

Because it has all the appearances of a fairly complex mimicry. Again, there does exist a scenario, no matter how unlikely, wherein the "stemlike tail," the bloated non-segmented body, and the tendency to hang from branches all developed at once, but if you think it's more likely than multiple successive generations and standard honing via natural selection, when all we know about this particular specimen is how it looks in photographs, you and I will forever be on different pages.

And believe me, I'm fine with that.

originally posted by: imjack
Beneficial genetic mutations do not have to take millions of years.

Of course not.

The point of the Darwin theory is that specific species become the predominant species through natural selection etc etc.

Natural selection refers to the fact that creatures which are better suited to their environment will experience enhanced survival and will pass their genes on more often. In this sense, the natural environment "selects" which traits enhance survival and which do not.

originally posted by: PhotonEffect
Have you ever heard of a mutational hotspot ?
...
Maybe it was just one mutation of large effect.

Maybe but very unlikely, and there's nothing in that link to suggest that a spider that doesn't look like a leaf will suddenly have one large complex mutation to look like a leaf.

originally posted by: PhotonEffect
a reply to: Greggers

I'm sorry but why is this "very unlikely" to occur?

It seems very unlikely that a complex mutation will happen, and in fact it was Darwin who correctly pointed out the absurdity of something as complex as an eye appearing as a random mutation. Creationists have latched on to his observation while ignoring the rest of Darwin's explanation on how more complex structures like eyes can evolve as a series of much smaller changes, and where we have good fossil records we can see evidence of these smaller changes over time.

www.talkorigins.org...

Claim CB301:
The eye is too complex to have evolved.

This is the quintessential example of the argument from incredulity. The source making the claim usually quotes Darwin saying that the evolution of the eye seems "absurd in the highest degree". However, Darwin follows that statement with a three-and-a-half-page proposal of intermediate stages through which eyes might have evolved via gradual steps (Darwin 1872).

Do you understand why the appearance of a complex eye from a single mutation would be absurd? If so then a single mutation for a creature to suddenly appear like a leaf when it looked nothing like a leaf before seems almost as absurd, using the same rationale. If you don't understand why those seem absurd, then I don't think you understand how many genes would need to simultaneously mutate in such a serendipitous fashion. The odds of that may not be zero but they are close to zero due to the complexity of the changes and the number of genes involved.

A more plausible alternative to slow and gradual evolution of a complex change is rapid evolution, which isn't as common as gradual evolution but sometimes it happens:

evolution.berkeley.edu...

In that scenario there are still lots of small changes instead of one highly complex mutation, but the small changes happen so rapidly in geological terms that it's like the "blink of a geological eye" as this Berkeley source puts it.

This "plenty of evidence" you speak of exists mostly in the lab using the same computer models and the same model species. Far less research in nature though, where the dynamics are much different.

There is plenty of evidence in the fossil record that's not a simulation, and even examples of rapid evolution observed in modern times, cited in the link.

Have we really observed it "in action in thousands of species, or perhaps thousands of times in the same few model species and simulations?

I haven't tried to count but it's many. My guess is it's in the thousands.

a reply to: Greggers

originally posted by: Greggers
Again, keep in mind, the purpose of my statement was to counteract the notion that there is something supernatural or unexplainable about adaptations such as these.

Sure, I get that, but even after substantial analysis there could be aspects which are unexplainable, scientifically speaking. My issue is that natural selection is too often used to fill gaps in our knowledge when it may be irrelevant, or at least unknown as to how much of a role it plays.

originally posted by: Greggers
Exactly. Just to be clear, there is NO SUCH THING AS PURE RANDOMNESS in classical physics, nor in biology. Genetic propensity is simply a way of saying that the unknown factors that influence how the dice roll are based upon the creatures existing biological composition.

Yes I agree, but we're not talking about randomness. We're talking about your claim that all mutations are accidents. The evidence doesn't support this notion.

originally posted by: Greggers
Because it has all the appearances of a fairly complex mimicry. Again, there does exist a scenario, no matter how unlikely, wherein the "stemlike tail," the bloated non-segmented body, and the tendency to hang from branches all developed at once, but if you think it's more likely than multiple successive generations and standard honing via natural selection, when all we know about this particular specimen is how it looks in photographs, you and I will forever be on different pages.

The one thing we can certainly agree on is that all we have is a photograph. But that's it. I believe the researchers have yet to fully sequence the genome of this thing, so I will leave you with this:

Analysis and understanding of a given mimicry system require a rather comprehensive knowledge of morphology, behaviour, ecology, and mutual relationships of animals usually in different classes—for example, wasps (Hymenoptera), flies (Diptera), insect-eating amphibians, reptiles, birds, and small mammals. Tracing the evolution of such a complicated system requires a detailed acquaintance with a large group of forms related to each of the animals involved. Such data, in fact, are seldom available.

www.britannica.com...

a reply to: Arbitrageur

originally posted by: Arbitrageur
Maybe but very unlikely, and there's nothing in that link to suggest that a spider that doesn't look like a leaf will suddenly have one large complex mutation to look like a leaf.

It's why I used the word "maybe". But, "very unlikely" is not a substantiated position. The purpose of that link was to show that mutations are not accidental. And there was more to that post than what you singled out.

Scientists are just now starting to fully sequence genomes, trying to detect, amongst other things, the genes involved in certain adaptations and if there are signals of selection present. New information is being realized every day, as well as more questions and puzzles. There are upwards of a trillion species out there, yet many folks suppose that we can paint the picture of evolution across all of them with just one brush.

originally posted by: Arbitrageur
There is plenty of evidence in the fossil record that's not a simulation, and even examples of rapid evolution observed in modern times, cited in the link.

The fossil record is a very useful tool, but most often it offers only very little about the ecological dynamics that lead to the phenotype of the specimen, especially when the fossils are incomplete. That's where the simulations/modelling come in. And unless we're fortunate enough to get a DNA sample, it's not very insightful about the underlying genome, where the true mechanics of adaptation reside.

originally posted by: Arbitrageur
It seems very unlikely that a complex mutation will happen, and in fact it was Darwin who correctly pointed out the absurdity of something as complex as an eye appearing as a random mutation. Creationists have latched on to his observation while ignoring the rest of Darwin's explanation on how more complex structures like eyes can evolve as a series of much smaller changes, and where we have good fossil records we can see evidence of these smaller changes over time.

www.talkorigins.org...

Claim CB301:
The eye is too complex to have evolved.

This is the quintessential example of the argument from incredulity. The source making the claim usually quotes Darwin saying that the evolution of the eye seems "absurd in the highest degree". However, Darwin follows that statement with a three-and-a-half-page proposal of intermediate stages through which eyes might have evolved via gradual steps (Darwin 1872).

Do you understand why the appearance of a complex eye from a single mutation would be absurd? If so then a single mutation for a creature to suddenly appear like a leaf when it looked nothing like a leaf before seems almost as absurd, using the same rationale. If you don't understand why those seem absurd, then I don't think you understand how many genes would need to simultaneously mutate in such a serendipitous fashion. The odds of that may not be zero but they are close to zero due to the complexity of the changes and the number of genes involved.

A more plausible alternative to slow and gradual evolution of a complex change is rapid evolution, which isn't as common as gradual evolution but sometimes it happens:

evolution.berkeley.edu...

In that scenario there are still lots of small changes instead of one highly complex mutation, but the small changes happen so rapidly in geological terms that it's like the "blink of a geological eye" as this Berkeley source puts it.

I'm sure you are aware of what pleiotropy is. You know that genes work in networks, very rarely on their own. One mutation or transposable element can have a big impact on many traits simultaneously. Most of the genome regulates expression vs coding for proteins. Adaptation can and does happen quickly thanks to the plasticity of the genotype and phenotype. With regards to mimicry, It is widely accepted that this type of adaptation may result from only a small number of mutations of large effect in a specific gene [cluster]. This not to say that adaptation doesn't happen by small changes either, only that this is not the only way it must happen, which is the prevailing view.

On an important side note though, Arbitrageur :
I don't know you personally and although we haven't interacted much over the years I've come to respect you for your contributions to the science forum and in general on ATS. You are well schooled, and you take the time to explain and teach things to people. There's not enough of that around here and it's why your physics thread will go down as one of the all time best.

So it's unfortunate that you took my quotes out of context, then tried to spin this into a creationist debate in a science forum citing sources only ever used in creationist debates which haven't been updated in 10 years. I understand why you are using the eye example, but the context of it is completely irrelevant to this discussion. I'm not arguing against evolution in the least, just that we shouldn't be jumping to conclusions about the way this particular adaptation occurred. I have questions about categorizing all mutations as accidents and while I don't adhere to the conventional view of evolution that is dominated by selection, that certainly doesn't make me a creationist which it seems you were implying with this post. I could be wrong with that assessment since apparently I take things too literally. So if that's the case then please accept my apologies.

Either way it's nice to engage with you about something other than physics (which I know is your specialty)

originally posted by: Greggers
Natural selection refers to the fact that creatures which are better suited to their environment will experience enhanced survival and will pass their genes on more often. In this sense, the natural environment "selects" which traits enhance survival and which do not.

There is no definitive "will" in the definition of natural selection. That's a misconception

Natural selection is a probability that on average a trait may confer just enough fitness to allow an organism to propagate it's genome.

But almost never does a trait act in isolation to confer an advantage. It takes the entire phenotype, i.e all traits working in concert. So the issue then becomes deciding which trait leads to selection, and which gene or genetic network gets eliminated or passed along. This is why we must look at the genome for signatures of selection, when we can't be out in nature actually watching it happen. It's not at all a straightforward science

originally posted by: PhotonEffect
So it's unfortunate that you took my quotes out of context, then tried to spin this into a creationist debate in a science forum citing sources only ever used in creationist debates which haven't been updated in 10 years.

Thanks for the kind words but you completely missed the point of my post, because I wasn't trying to spin it into a creationist debate. Instead I was trying to explain how even in the debate about creationism, there was no debate on either side about the human eye being too complex to evolve in a single mutation.

Darwin said it was too complex for that, modern evolutionary biologists agree, and even the creationists agree on that point, I thought everybody would agree, even you! So while there were some deeper debates that people didn't agree on, I wasn't referring to any of those. I picked a point that nobody argued with on any side of the debate that I'm aware of and I thought you would agree with it too but I still don't know if you do or not.

So maybe this the change from a normal spider form isn't quite as complex as the human eye occurring in a single mutation, but it still seems quite complex to me. To say it might happen in a single mutation seems like an extraordinary claim and you haven't provided any extraordinary evidence to back it up, rather the evidence you've provided doesn't seem to support that claim to the extent you seem to think it does.

So my point had nothing to do with creation science and everything to do with the fact that everybody on every side of the debate accepted that extremely complex mutations don't happen all at once. I can't prove a negative so I can't prove the leaf mutation can't happen all at once but it will take a lot more evidence than you've provided so far to demonstrate such a dramatic change is possible in a single mutation.

A much simpler mimicry mutation involving patterns of pigment distribution could occur in a single step, maybe something like this:

Eye knew it! Markings on butterflies really DO mimic a predator's gaze


Even in that case I would expect multiple mutations of refinement but a single mutation is at least plausible. However the mutation to make a spider look like a leaf is far more complex and thus far less plausible for the entire change to have happened in a single mutation.

originally posted by: PhotonEffect

originally posted by: Greggers
Natural selection refers to the fact that creatures which are better suited to their environment will experience enhanced survival and will pass their genes on more often. In this sense, the natural environment "selects" which traits enhance survival and which do not.

There is no definitive "will" in the definition of natural selection. That's a misconception

It may be a misconception, but not by me. Of course natural selection has no will. The word "selects" tends to make people think there must be a will involved, but selection has nothing to do with will.

Since the process has been called "Natural Selection" for a very long time, one would think people would be accustomed to this by now.

originally posted by: Arbitrageur

originally posted by: PhotonEffect
So it's unfortunate that you took my quotes out of context, then tried to spin this into a creationist debate in a science forum citing sources only ever used in creationist debates which haven't been updated in 10 years.

Thanks for the kind words but you completely missed the point of my post, because I wasn't trying to spin it into a creationist debate. Instead I was trying to explain how even in the debate about creationism, there was no debate on either side about the human eye being too complex to evolve in a single mutation.

Darwin said it was too complex for that, modern evolutionary biologists agree, and even the creationists agree on that point, I thought everybody would agree, even you! So while there were some deeper debates that people didn't agree on, I wasn't referring to any of those. I picked a point that nobody argued with on any side of the debate that I'm aware of and I thought you would agree with it too but I still don't know if you do or not.

For the record, I just wanted to say that your point was articulated well and was easy to understand for anyone interested in actually understanding it.

So maybe this the change from a normal spider form isn't quite as complex as the human eye occurring in a single mutation, but it still seems quite complex to me. To say it might happen in a single mutation seems like an extraordinary claim and you haven't provided any extraordinary evidence to back it up, rather the evidence you've provided doesn't seem to support that claim to the extent you seem to think it does.

Yep.

a reply to: Arbitrageur

originally posted by: Arbitrageur
.. I wasn't trying to spin it into a creationist debate. Instead I was trying to explain how even in the debate about creationism, there was no debate on either side about the human eye being too complex to evolve in a single mutation.

Darwin said it was too complex for that, modern evolutionary biologists agree, and even the creationists agree on that point, I thought everybody would agree, even you!

Look, it's no surprise that Darwin would opine gradualism, it was the foundation of his theory, and the only way he thought evolution occurred. I understand you're trying to make a point, but it seems like a stretch to say that creationists now agree with him about how the eye evolved. I don't know where that idea came from, but if you've rummaged through the O&C forum lately you'd realize this isn't the case. The eye argument has been one of the hallmarks of creationists' beef with evolution because of what they call "irreducible complexity", so I'd be surprised if they've suddenly conceded that idea. Regardless I see no reason to bring it up here.

originally posted by: Arbitrageur
So maybe this the change from a normal spider form isn't quite as complex as the human eye occurring in a single mutation, but it still seems quite complex to me. To say it might happen in a single mutation seems like an extraordinary claim and you haven't provided any extraordinary evidence to back it up, rather the evidence you've provided doesn't seem to support that claim to the extent you seem to think it does.

So your issue is with the perceived complexity of the Poltys' adaptation as a leaf, and the inconceivability of it arising from a mutation of large effect. Maybe to you it sounds extraordinary, but the manner by which crypsis/mimicry evolves has been debated about for well over 100 years (see Punnett, Fisher, Goldschmidt for starters). Mostly re: whether or not it happens in big leaps vs. small incremental steps. A good summary here.

originally posted by: Arbitrageur
So my point had nothing to do with creation science and everything to do with the fact that everybody on every side of the debate accepted that extremely complex mutations don't happen all at once.

Well, again, I think your point was misplaced. Whichever way the eye evolved has no bearing on how everything else must evolve, especially this spider. Everything in biology is complex, so I don't see that as a reason to assume that several mutations across several genes over several thousands of years were required.

Perhaps you've heard of the hopeful monster theory. It was first postulated by Richard Goldschmidt in the mid 20th century. The idea raised a ruckus mostly because genetic evidence was lacking (it was 1940) and also because large mutations were thought only to be lethal (again, an old idea). Times have changed though, and so has the evidence. The return of the hopeful monster? Some more reading on the subject. Point is, mutations of large effect are important to adaptation and mimicry, so no it's not extraordinary in the least.

originally posted by: Arbitrageur
A much simpler mimicry mutation involving patterns of pigment distribution could occur in a single step, maybe something like this:

Eye knew it! Markings on butterflies really DO mimic a predator's gaze

Even in that case I would expect multiple mutations of refinement but a single mutation is at least plausible. However the mutation to make a spider look like a leaf is far more complex and thus far less plausible for the entire change to have happened in a single mutation.

A mutation of large effect need not happen in a protein coding region to have a large impact either, as one occurring in a GRN can have great influence on expression of phenotypes during development. Epigenetics also plays a significant role in gene regulation, that more and more evidence is showing is induced by environmental cues. There is known evidence from research in butterfly mimicry that a single gene or a supergene (i.e. a tight cluster of genes) is responsible for the color patterning in wings. Supergenes in mimicry of butterfly wings does not produce intermediate forms. And don't forget the possible pleiotropic effects that just a single mutation can impose on multiple traits.

It seems for now biologists are maybe finding some common ground with punctuated leaps followed by stepwise refinement. europepmc.org... But the debate is far from settled and tends to be dependent on a number of factors, most of which we don't even know with regards to this spider. So again, that's why I said "maybe".

Here is evidence that evolution in one leap can happen, this instance in moths: Evidence of repeated and saltational evoltuion in sphinx moths.

If I haven't addressed these points in a satisfactory manner then please let me know where I missed the mark and let's move forward. I ran out of space and had to edit this epic post down, but I have more resources. In the end the point is that evolution of mimicry of this type can happen in leaps and not necessarily by incremental small steps overs thousands or millions of years.

But for now consider these images of another mimicking spider in the same Poltys genus as our friend in the OP:
They mimic a tree stump, P. illepidus and twigs P. elevatus




Perhaps there's a foundational body plan involved here. Questions abound.

originally posted by: Greggers
It may be a misconception, but not by me. Of course natural selection has no will. The word "selects" tends to make people think there must be a will involved, but selection has nothing to do with will.

Since the process has been called "Natural Selection" for a very long time, one would think people would be accustomed to this by now.

I was referring to your usage of the word will in your claim about natural selection.

originally posted by: PhotonEffect

originally posted by: Greggers
It may be a misconception, but not by me. Of course natural selection has no will. The word "selects" tends to make people think there must be a will involved, but selection has nothing to do with will.

Since the process has been called "Natural Selection" for a very long time, one would think people would be accustomed to this by now.

I was referring to your usage of the word will in your claim about natural selection.

Yep. And it sounded like you needed a primer in basic biology, since me saying that the environment "selects" the trait denotes no will, but rather the natural process as described initially by Darwin and subsequently by thousands of other scientists.


Plus, there was a reason the word "selects" was in quotation marks.

originally posted by: PhotonEffect
aybe to you it sounds extraordinary, but the manner by which crypsis/mimicry evolves has been debated about for well over 100 years (see Punnett, Fisher, Goldschmidt for starters). Mostly re: whether or not it happens in big leaps vs. small incremental steps. A good summary here.

You mean there are actual scientists who for well over one hundred years have postulated that this happens in small incremental steps? Huh.... It sounds to me like what I said in my original post did in fact bear some resemblance to science. Imagine that!

I'll see you in three weeks when you get around to reading this.

a reply to: Greggers

Once again, you're showing your lack of basic comprehension of english sentences.

originally posted by: Greggers
You mean there are actual scientists who for well over one hundred years have postulated that this happens in small incremental steps? Huh.... It sounds to me like what I said in my original post did in fact bear some resemblance to science. Imagine that!

I'll see you in three weeks when you get around to reading this.

Uh, no, get your head out of your own bubble.