Stick Insects force Evolutionary Rethink

New Scientist ^ | 15 January 03 | Nicola Jones

[Ahban]

SRC="/img/shim.gif">

Wings could be a passing phase for the giant prickly stick insect (Image: OSF)

Researchers have discovered that on a number of occasions in the past 300 million years, stick insects have lost their wings, then re-evolved them. Entomologists have described the revelation as "revolutionary".

Michael Whiting, an evolutionary biologist from Brigham Young University in Provo, Utah, and his team stumbled upon the finding while examining the DNA of 37 different phasmids, the stick and leaf insects famous for camouflaging themselves against plants, in a bid to work out their family tree.

	The big wing switch

Entomologists have assumed that wings only evolved once in insects. The received wisdom is that a winged ancestor produced the winged phasmids we see today. The 60 per cent of stick insects that do not sport wings will, this thinking goes, have jettisoned them along their evolutionary journey so they could expend more energy on reproduction and less on flying.

But Whiting's analysis shows that the very first stick insect, which appeared 300 million years ago, had already lost its wings and that stick insects re-evolved the structures at least four times (see graphic). The study covers only 14 of the 19 known sub-families of phasmids, so it is possible that wings reappeared even more often.

Beyond repair

Researchers assumed wings could not come back once lost as the genes needed to create them would mutate beyond repair once the wings disappeared. But Whiting says there is evidence from the fruit fly Drosophila that the same genes contain instructions for forming wings and legs.

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Weblinks

Zoology, Brigham Young University

Evolution, Berkeley

Nature

If the same were true for stick insects, there would be an evolutionary pressure to stop wing genes from mutating, even in the insects that did not have wings. Those genes could then be turned back on in the future.

Whiting says, however, that while wing re-evolution may seem unlikely to insect researchers, the basic idea of switching regulatory genes off and on is well accepted. Even a single gene can sometimes switch on the growth of a complex structure - studies indicate that a master gene called Pax-6, for example, might control the development of eyes in all creatures that have them.

So Whiting suggests that eyes too could have disappeared and reappeared in animals over time. "I remember sitting down with entomologists and hearing them say 'impossible, impossible, impossible'," he says. But "re-evolution is probably more common than we thought".

[merak]

And yet every mature insect was once a segmented worm.

You sound like some sort of an expert.

How did metamorphoses evolve?

For that matter, nobody seems to have any real proof of evolution but we know that metamorphoses works. Has anybody ever investigated the possibility that metamorphoses may have been the basic mechanism for the world's biological diversity?

[Ahban]

But don't you see the lack of mechanisms on your #38? Its all conjecture. Unless that first worm had the genetic potential to develop abdomen, legs, antenna, wings, etc than that info had to be OBTAINED from somewhere.

Here (in the article) we have evidence that seemingly long-lost information can re-appear multiple times after a fifty million year break (ha!). If this is so, why do we not have earthworms with velvet-worm type legs appear from time to time? Or for that matter, the appearance of wings on any number of wingless insects, or eye spots on things that lack them. The observations that would connect your dots have yet to be made in the field, only in the imagination.

"If I can imagine how it might have happened then you must accept that it DID happen" is not my idea of science (not that I am accusing you of this).

Without observations, one cannot move past the HYPOTHESIS stage of the scientific method.

[Sentis]

"Do you mean that 20% of the population have the wing gene intact, or that any given individual has 20% of the whole infoset needed for wings? If the latter, does another member of this group have a different 20%? "

It doesn't matter the law of averages says that the recombination will occur on occasion. My example is very simple and isn't how genes work exactly, in any case, so its just an example of why the genes would recombine and isn't meant to be taken literally. To discuss the specifics we need a classroom type forum and an internet debate won't work.

As to numbers I'm quite willing to discuss numbers but it is difficult to discuss anything on a forum like this especially when most people don't even have a grasp of simple genetics much less basic knowledge of how DNA works.

As to the number crack I have noticed when creationists discuss numbers they tend to exaggerate the meaning or not grasp the concepts so why would anyone bother to discuss it with them. I have on numerous occasions sought a meaningful discussion only to be insulted which you probably will engage in as you have already sank to back-wards insults of all evolutionists.

[psychoknk]

In biology, there is a term, epistasis, which describes a gene that controls the expression of another gene. Such genes are fairly common; think of albinos. Albinos have all the genes required to give their skin pigment; they are without pigment because another gene is defective, and doesn't allow the pigment to be expressed. In this situation, a mutation in the gene does not act half-way, or partially. It completely turns off the expression of pigment.

My guess would be that there is a similar gene in these insects. It controls whether or not they have wings. In times when it is favourable to have wings, these genes allow for the expression of the wing genes. In times when it isn't, well, you get a lot of "albinos." I restate that this is a guess, however, it is plausible, and far more likely than your God periodically changing his mind (I see no mention of God changing his mind about creation in Genesis.).

As to the whole debate on whether or not new features can develope: it is an interesting arguement and one I have heard before. The main flaw with it is that it doesn't take into account all the "garbage" DNA beings have. It is fully possible for an organism to survive with the DNA for something it doesn't need; the cost of maintaining and replicating this DNA isn't significant enough for competing organisms who do not possess this DNA to have an evolutionary advantage. As such, over time, a new part may be added. It could be small at first, such as a protein that is able to detect light. Over time, the protein could be refined, and various versions of it to appear in the plant. Rods and cones, the two different receptors for light in our eyes, both contain a protein called rhodopsin. Perhaps this is the functional part of the original protein. Animals that had this protein were able to survive better than those who did not, and later on, some of their descendents were able to question why they had it. The animals who didn't have this protein - well, competition is a $*#(%, and they either died, or didn't develope the traits necessary for philosophy.

[Buckeye Bomber]

Dear Lord. What school district in what state do you teach? My kids will never go to school there. I'd prefer to send them somewhere where the Bible doesn't pass for a scientific text.

[balrog666]

Welcome to the club!

[Stultis]

But don't you see the lack of mechanisms on your #38? Its all conjecture.

However that may be, it was a relevant refutation of the post I was responding to!

I don't have the expertise, nor do I feel the need, nor is it a remotely reasonable standard of evidence, to explain in full detail all the paths of evolution, most of which occured among creatures all traces of which are permanently lost.

[Ahban]

As regards to the "small mutation" required to get wings back, please see my #40, and not that even the evolutionary scientists conducting this study were amazed that wings were reacquired multiple times.

As far as ruling out, a priori, the idea that God is responsible for some of this stuff, I will not but such limits as to how God might choose to play in His garden.

As far as the "junk" dna, the more we learn, the less "junk" there is. It may be a function of our incomplete knowledge rather than true "junk". I remember a study recently where most of the "junk" in humans and some distant critter was CONSERVED. If it is conserved, it is NOT junk, it just has some use we have not discovered yet.

Thats no refutation of creationism. Heck, I've cut and pasted some code in my time too. I left a little harmless junk in some of it. THAT code did not evolve by itself.

That brings me to my last point. The identical genes that are in bacteria and humans, the so-called "remants of lesser organisms" in our DNA is actually powerful evidence for creationism. Unless there is a mechanism by which we can acquire bacteria genes in every cell of our body, ID is the only explanation by which the EXACT same genes are found in a given bacteria and humans, but lacking in many types of critters alleged to be between us.

Think about it. Code was ripped from that bacteria and used in say, mammals. It was not needed and not used in fish, amphibia, birds, or reptiles. How did that happen by evolutinary means? God went to his box of code modules and said, "I have not esed this one in a while, but if I stick it HERE, it will do the job".

Crazy? Only if you decide in advance that it must be wrong.

[VadeRetro]

You sound like some sort of an expert.

Thanks, but I fake it.

How did metamorphoses evolve?

Think about what metamorphosis really does. It lets the growing insects and the adult insects live in different ways on different food--and thus not compete across generations. Or you can think of it as exploiting more than one niche at a time. Adult butterflies sip nectar while caterpillars chomp leaves and wait to spin their cocoons.

Most of the mechanism is already in place, since all the sexual multicellulars already start from a fertilized egg and tend to resemble, at various stages of their history, different primitive stages of their development. You were once a one-celled animal, then a simple colonial multi-cellular, then a chordate, then a vertebrate, etc.

So in any event, you have to go through the stages. There can be environmental pressures that say there's an advantage to be had in staying stuck in a certain stage for a while, just to grow to a certain size or whatever. So you have the stages, you have some pressures conveying an advantage if your species stays at a stage for a time and exploits a different niche from the adult. Stumble onto the right answer, beat out the competition.

[Pharmboy]

You are on a roll my freepfriend...

[Pharmboy]

Uh oh...it's internet therapy time at the sanitarium again (with apologies to PatrickHenry who said it first).

[Ahban]

But I was not insulting you, therefore I could hardly be insulting all evolutionists.

It is a pity you are choosing not to elaborate on your stats...... I thought I had found an exception to my experience of evolutionists being extremely adverse to having their ideas subjected to numerical analysis.

[f.Christian]

If you belive the hype // meta-mega morphofoolisness of evolution . . . you need meds - - - daily indoctrinations too ! ! !

"The most important cultural event of the past decade is the ongoing release of the film version of J R R Tolkien's The Lord of the Rings. No better guide exists to the mood and morals of the United States. The rapturous response among popular audiences to the first two installments of the trilogy should alert us that something important is at work. Richard Wagner's 19th-century tetralogy of music dramas, The Ring of the Nibelungs, gave resonance to National Socialism during the inter-war years of the last century. Tolkien . . . does the same ((link )) - - - for Anglo-Saxon democracy."

[Sentis]

why expand on stats that I stated in the original and the second post that are merely extrapolations of the argument and not serious data. It was an example, give me some real numbers to deal with rather than numbers I made up to make a point. A insult is a insult is a insult regardless of who you directed them at, remember you started them. :)


Here is a number we can discuss, what number of years do you believe that this Earth has existed?

[Ahban]

Your points are addressed in my #40 and #48.

[f.Christian]

To: Dataman

dm...

You exercise faith minute by minute-- look it up in the dictionary. It is not faith you despise, but faith in God.

fC...

evolutionist . . . faith // love in lies (( EVOPOLUTION )) ! ! !

[Ahban]

I think the Earth has existed for about 4 and a half billion years.

As far has who started the insulting, read #24 and the last bit of #23 and tell me which side is exercising high class restraint and which side is hurling abuse.

[psychoknk]

As far as the "junk" dna, the more we learn, the less "junk" there is. It may be a function of our incomplete knowledge rather than true "junk". I remember a study recently where most of the "junk" in humans and some distant critter was CONSERVED. If it is conserved, it is NOT junk, it just has some use we have not discovered yet.

What study are you referring to? And what do you mean by conserved? Do you mean that cells actually go and make sure junk is present? In some cases it is true; there are pieces of DNA that are useless to the body but get copied and put into other places on the genome. It exists solely because the DNA has an aptitude for it, and doesn't kill the cells harboring it. Read Richard Dawkin's The Selfish Gene.

EXACT same genes are found in a given bacteria and humans, but lacking in many types of critters alleged to be between us.

I haven't heard of such DNA. I am not denying it exists, but it may be possible that you misinterpreted the results of an experiment (i.e. there are bacteria known as archaebacteria which live in extremely savage conditions which more closely related to humans than "regular" bacteria.) In either case, I would be very interested in seeing an article about this.

[Ahban]

I think the Earth has existed for about 4 and a half billion years.

As far as who started the insulting, read #24 and the last bit of #23 and tell me which side is exercising high class restraint and which side is hurling abuse.

[Sentis]

at least we can agree on the age of the earth. :)