Well, it seems a researcher has rediscovered that genetically, evolution is not “Use it or lose it.”
http://www.sltrib.com/2003/Jan/01162003/utah/20633.asp
This is news… how? Anyone remember the bit where they got the fruitflies to regrow their front mandibles into legs, if I recall correctly?
You know what this means, don’t you? If re-evolution is possible, then the Aquatic Ape Theory comes out of the closet and into daylight. That’s the one where humans evolved from aquatic mammals, which would involve mammals evolving on land, then going into the water and evolving into marine mammals, then evolving into marine hominids from some unspecified marine mammal protoancestor, and then coming back out onto the land and evolving back into terrestrial hominids (humans).
Geez,Duck Duck Goose , I could barely get out of bed, much less decide the species needs to become amphibean. (Ba da bing).
I think that if it’s true, which is somewhat dubious, it’s going to shed some interesting light on the preconceived notions that evolution theorists hold to. (FWIW, I believe in evolution).
I believe this is the study that the OP referred to (but I could be wrong):
http://www-acs.ucsd.edu/~idea/wellsshrimp.htm
I read a book by a Jonathon Safarati just last night! He writes that the gene mechanism discovered dealt with placement of existing codes. So it shuffled the leg growth to where the antenna should be, but it was not new genetic information, just a different order. Interesting point.
It will take a hell of a lot more than the concept of re-evolution to make that scenario even remotely plausible.
As for flying stick bugs, it is interesting that they might have re-evolved wings, but not, in my opinion, all that earth-shattering. So long as their non-flying ancestors still had the genes for the wings, it isn’t all that surprising that these genes would eventually be re-expressed. Now, if the wing genes were completely absent in the ancestors, and then showed up anew later on, that would be exciting!
To quote the first line of the article:
Brigham Young University researchers have uncovered genetic evidence in stick insects – a group of bugs that resemble tree twigs with legs – that could force scientists to rethink long-held beliefs involving a part of the theory of evolution.
And there’s your problem right there. In one sentence, the topic slides from an intriguing new discovery in entomology all the way to presenting the impression that evolutionary theory itself is somehow in jeopardy. That’s the trouble with Sunday supplement-level science writing in general, it seems–no sense of perspective. One can also perhaps understand how the Salt Lake Tribune would like to consider Brigham Young University as being the vanguard of a revolution in biology. It certainly seems like this would upset a lot of apple carts in the halls of insect taxonomy, I’ll give them that.
Not really, at least not to me. I really don’t see what the big deal about this is. Think about it. We see examples of convergent evolution all the time. Hummingbirds and Sunbirds look very similar, yet have completely different evolutionary origins. The sunbird didn’t need to have dormant humming bird genes to evolve it’s beak and hovering wings, it did it on it’s own because it was in a similar environment.
So re-evolution isn’t that surprising. The stick insect has wings, but the environment changes, and it loses those wings. Later, the environment changes again to one where wings would be an advantage. The same evolutionary pressures are there now as when insects developed wings the first time, so why can’t they do it twice? They could use the dormant genes from the wings of their ancestors, or as the humming bird and sun bird show us, they could use a completely new set to get the same result.
Well, I think it’s a good point DDG makes, but I have an emotional, but not logical amount of support for the Aquatic Ape theory. Behavorially and hair pattern wise, it seems to make so much sense!
If only there was evidence.
As far as this goes, I was thinking essentially the same thing as Bmalion. Gen1 has wings. Gen2 has a transcription error, a byte-shift stops the wings from developing. Gen3-3000, no wings. Gen3001 has a reverse byte-shift error. Wings.
What it does do is give support for punctured equlibirium, by showing a method of rapid change being possible. I think.
The problem is you are comparing two birds: both have the same basic genetic makeup (because both have a common ancestor), and therefore operate under many of the same constraints, as well as possess similar degrees of plasticity with repsect to their variation. So, given the similar starting points, it is not all that surprising that, also presented with similar environments, two lineages might converge.
A better example would be vertebrate flight (as opposed to insect flight) – it’s only evolved three times in the entire history of verebrates. But, here’s the kicker: each time, the exact solution was rather different. The wing structures of birds, bats and pterosaurs have similar general forms (because of similarity of function, as well as constraints imposed by all having a common tetrapod ancestor), but are quite different in any number of important details.
Similarly with insects: if insect wings evolved only once, then we would expect to see the same general structure throughout the history of flying bugs. If they evolved separately, we could reasonably expect differing solutions, based on the particular lineage and its inherent constraints.
This is why I see a true re-evolution of wings as being more than simple convergent evolution; that a wing must represent an airfoil is fairly essential to its function. But, beyond that, there aren’t many environmental factors which would necessarily dictate a particular solution. Similar selective pressures do not ensure that a given adaptation will evolve. So, there is no real expectation that just because, in a given environment, a given trait might be advantageous that it will evolve. The organisms in that environment must be capable of generating the necessary pool of variation, and a variation which can be successfullly built upon must emerge from that pool. If the flying stick-bugs’ ancestors did not have the genetic equipment necessary to make wings (or a precursor thereof), there is no reason to expect that their descendants would acquire them.
The evolution of complex structures from scratch is generally accepted to be a rare (though not necessarily one-time-only, as the article states) event. However, if, as in this case, the genes to make wings were already there all along, simply lying dormant, well, that’s not so special.
*Originally posted by Beeblebrox *
** We see examples of convergent evolution all the time. **
I’m beginning to think we don’t.
** Hummingbirds and Sunbirds look very similar, yet have completely different evolutionary origins. The sunbird didn’t need to have dormant humming bird genes to evolve it’s beak and hovering wings, it did it on it’s own because it was in a similar environment.**
Similar environment? So what ever lives in trees and eats the same food will eventually wind up looking like a hummingbird? What about insects?
**The stick insect has wings, but the environment changes, and it loses those wings. Later, the environment changes again to one where wings would be an advantage. The same evolutionary pressures are there now as when insects developed wings the first time, so why can’t they do it twice? They could use the dormant genes from the wings of their ancestors, or as the humming bird and sun bird show us, they could use a completely new set to get the same result. **
But that’s my problem with that line of reasoning. If the genes are already there, then growing or not growing is merely a matter of changes within an existing type. Yes, evironmental pressures do have an effect, but not to the point of creating any new information. Sort of like passing a law that only red-haired people can have babies. Eventually you’d only see people with red hair. But if you remove the law, then as soon as baby is born with black hair, you’d know that it is not new genetic information, only old information allowed to be re-used. I agree with your example of dormant genes, but we do not see evidence of a “completely new set” do we?
Sorry about the code-clumsiness, I’ve got to preview my answers more often!:smack:
Created ‘from scratch’ but lying ‘dormant’ ? that doesn’t seem to make sense. So the theory is that the genetic information code for how-to-make-wings was accidently generated, but not used, until much later?
No, we don’t, at least not here. All I was saying is that I wouldn’t be suprised to see two separate instances of wings evolving in insects. It was a hypothetical responding to what Darwin Finch said he would find exiting.
He touched on a better example than my birds when he mentioned vertebrate flight. It evolved three separate times with three separate gene sets. Why would we be suprised to see this happen in insects? I never said they had to be the exact same wings, just that the thing would be able to fly. Insect flight evolving twice using seperate gene sets wouldn’t be that suprising to me, especially considering their short life span. In short, if that hypothetical were to come true, it wouldn’t shock me in the least.
Mind you, I’m not saying it will happen or that it has happened, just that it could.
Well, the basic problem here is that if the genes aren’t being used, mutations will turn them into pseudogenes. So the real questions are as follows:
1.) What kept the genes from turning into pseudogenes?
2.) Does this study indicate that it’s easy to turn on and off complex structures?
The answer to 1), from what I’ve read, is that the genes used for wings are generally the same ones used for legs. (I can’t provide a link to Science’s news article, because it requires a membership.) Thus the bulk of the genes don’t really disappear- they just quit being used for wings, presumably because of mutations to simple regulatory regions.
As for #2, that’s no surprise. We’ve known that for ages. Only two mutations are needed to make a fly grow four wings instead of two, for example.
The real significance of this study is that it teaches us a little more about the regulatory pathways involved in forming complex structures, and suggests that because different structures share the same pathways, some structures can go dormant until needed. All in all, more evidence for evolution.
As for Jack Sarfati, bear in mind that he once hailed the genetic similarities between birds and reptiles as evidence against evolution. If he can make that kind of mistake, I’d take anything else he says with a grain of salt.
Ah, I got a good analogy for my earlier point. There’s a fish. It’s genes make it a great swimmer, but then it moves into tidal pools and starts eating bugs. Over time it develops stumpy little fins and can crawl around on the bottom and even spend short times on land. Eventually, it’s ancestors spend almost all their time on land. They develop lungs, legs, and teeth. These pack hunters look a lot like wolves, and have moved on to much larger prey than bugs. Fish become easy prey and the animals wade out into the water alot. Eventually, their ancestors are spending all their time in the water. They lose their hair, their hind legs fuse and we have… a dolphin!
The dolphin’s genes make it a good swimmer, but they are not dormant fish genes. All this time we have stayed in the sub phylum vertebrata. It wouldn’t suprise me if the class insecta were to have pulled something similar off during their millenia on this planet.
I agree with Ben, that the work is interesting and important, but the article makes it sound like re-evolution should be shocking. It doesn’t shock me, regardless of the genetic mechanism.
That really doesn’t have a lot to do with the study in question, though. The winged stick insects all have very similar wings- not just analogous wings like bats and birds. That’s why they’ve explicitly ruled out convergent evolution in favor of the original wings going dormant.
Actually the “created from scratch” bit was a separate clause: “created from scratch” is relatively rare, but does not appear to represent what happened in the stick-bug example. The stick-bug’s ancestors’ had the genes. These genes were later switched off, then even later switched on again. My point is that this type of “appearance of new characters” is probably significantly more common than the “created from scratch” version; therefore, to me at least, less exciting, though nonetheless interesting.
And I agree, Beeblebrox, that re-evolution or convergent evolution or any other kind of evolution may not be shocking , but it’s still darned fascinating 
Ben, yeah, I know. All my posts in this thread are about a hypothetical scenario, and had little to do with the cited study; They were instead directed toward a small remark made by Darwin’s Finch.
Sorry for the highjack.
Darwin’s Finch, I agree, it is fascinating. All this stuff is. Anyway, sorry for taking us so far afield on such a minor thing.
[just wanted to say “good point” to Terrifel]
Carry on, with the bugs ‘n’ stuff…
I’m afraid I don’t understand. What is the point, exactly?