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".

[Ahban]

Wings were lost and then re-evolved at least four times in STICK INSECTS ALONE? Then how many times have wings been re-gained in all families of insects and other creatures? Surely more than dozens. Hundreds? And when these newly re-gained wings pop up out of nowhere, for every time it "takes" and results in a new genus there should be many thousands of examples where a mutation occurs, but is not passed on, or does not entrench itself and create a new population. Yet we have never observed wings, or ANY complex structure, arising out of nothing.

Even if we did, it says nothing to how the wing genes came about in the first place. The more we know, the less naturalistic processes explain what we know!

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[Ahban]

Wonders of Evolution Ping

[William McKinley]

Great pic for this thread. LOL

[RobRoy]

Oh no! Not another evolutionary "rethink."

[Ahban]

The grasshopper in post #2 loses and then re-evolves wings every dozen posts, if you don't believe it, it is because you are a closed-minded, ignorant, bible-thumper who is afraid to face the truth! Excuse me while I step to the den and evolve a complex new structure. HeHe.

[newgeezer]

...in a bid to work out [the insects'] family tree.

One wonders whether this team's parents still cling to even the slightest hope that their once-bright little boys and girls will ever become productive members of society, instead of welfare (research grant) recipients.

[Junior]

They're at it again ...

[stylin19a]

Do I have this right...a stick insect lost it's wings, got 'em back, so that proves it evolved into......itself ?
Or is it.. the stick insect did NOT have wings, grew wings and evolved into..itself ? then lost it's wings and evolved into itself...again ?

[merak]

Wings are the least of the problems involving insects from the point of view of evolution. Insects are presumed to have evolved from segmented worms and, AFAIK, the simplest insects are just vastly more complicated than the most complex worms.

[RobRoy]

Those BYU guys, always obsessed with family trees!

[RobRoy]

>>Do I have this right...a stick insect lost it's wings, got 'em back, so that proves it evolved into......itself ?
<<

Maybe it just takes 'em off at night, when it goes to bed.

Ever try to sleep next to someone that's forgotten to take their wings off. "Ow! you pulled my wing!" My wife's an angel and every now and then even SHE forgets to take them off before bed.

[Buckeye Bomber]

It's not that complicated of a procedure. At one point, it must have been adaptive to have the wings, so the animals with wings survived to mate more often than without. At another, it was adaptive to not have wings, so there was a glut of the creatures without wings.

If you accept the modern theory of genetics (what else is there?), you have to accept evolution as at least the best we can do for now.

You don't "evolve" things. Mutations occur in genes at random. If it is a beneficial mutation, the animals with the mutation have an advantage and are able to procreate more widely. If it is not a beneficial mutation, then no change occurs. When people say that bacteria are becoming resistant to antibiotics, and then say evolution is "just a theory", they obviously have no idea what they are talking about. Without evolution, there is no modern biology. Anti-evolutionists believe that when something wierd that doesn't exactly fit into Darwin's theories comes up, they have defeated evolution. They can't attack the elephant, so they attack the flies around it. Until a better theory comes up, thoroughly researched and examined by impartial scientific researchers, evolution is macrobiology.

[EBUCK]

The genetic data exists even if not used...it would be a mutation for a wingless stick bug to have wings (just like webbed feet are an anomoly in us) but if that mutation proved usefull to the bug its offspring would stand a higher chance of surviving. Is that so hard to understand?

In humans there is a relatively common mutation in some south american people to grow hair all over their bodies. Considering that ice ages are geologically common eventually that mutation will probably come in handy. Then when it warms up again the trait will no longer be favored by the environment and will therefore be bred out but the data for the hair will remain (as it obviously has even though it isn't an environmental imperative).

[VadeRetro]

Insects are presumed to have evolved from segmented worms and, AFAIK, the simplest insects are just vastly more complicated than the most complex worms.

And yet every mature insect was once a segmented worm.

[CalConservative]

When people say that bacteria are becoming resistant to antibiotics, and then say evolution is "just a theory", they obviously have no idea what they are talking about.

Two points: 1) bacteria resistance to antibiotics and insects gaining and losing wings hardly proves evolution. In both cases, the information is already there and we are merely talking about variations within that genus or species. In no case does a mutation add information to the genetic code. Even in the case of beneficial mutations, the information is already there and, in many cases, some of the information is lost. This is the case of bacterial resistance to antibiotics; and,

2) This, once again, is confusing variations (or micro-evolution, if you like), which we can observe, with macro-evolution, which we do not observe.

[PatrickHenry]

Probably some of you were pinged earlier by others, but I can't avoid some duplication.

[This ping list for the evolution -- not creationism -- side of evolution threads, and sometimes for other science topics. To be added (or dropped), let me know via freepmail.]

[Buckeye Bomber]

Macro-evolution only occurs after micro-evolution. Without micro-evolution, there is no macro-evolution. Even so, there is no better theory than evolution (micro and macro working together) for how speciation occurs. If you have a better theory, I'm ready for it. The only arguments raised against evolution are saying that's it's false. Then what is what really occurs?

We can observe how evolution happened using the fossil record. In fact, many species that are related genetically still exist today. We can analyze the genomes of these species for their similarities. Science isn't always what we can see. Data analysis is a large part of it also.

[MattAMiller]

2) This, once again, is confusing variations (or micro-evolution, if you like), which we can observe, with macro-evolution, which we do not observe.

You might not observe it but scientists have.

Anyway, what is this iron clad law which states that genetic information cannot be added?

[f.Christian]

data!