A Case Of Convergent Evolution, Oh My!

I have to wonder what the creationists will say about this? The usual hand waving and wailing about how they are still crickets I suppose. This is another nail in the coffin for creationism.

I was perusing one of my favorite sites this morning National Geographic’s Phenomena, home of a handful of great science blogs. Ed Yong’s “Not Exactly Rocket Science” has the post titled “The Silence of the Crickets” (x2 which was odd, but read on)

There is a species of cricket on the Hawaiian island of Kauai that is being predated by a parasitic fly and I quote: “whose larvae burrow inside them and eat them alive.” These flies zeroed in on the crickets by listening to the characteristic cricket chirp, then did the nasty business of implanting eggs when they found the source of the chirping.

An observant professor Marlene Zuk, PHD, University of Michigan, who had been studying these crickets had noticed on subsequent trips that the crickets chirp was being heard less and less every trip. An investigation shows why. The crickets were caught, in real time, evolving wings that no longer allowed for chirping. The crickets that had flatter wings which were bad at chirping were surviving, because they were invisible to the parasites. The survivors offspring of course had wings unsuitable for chirping to the point now where there are hardly any chirpers left. Which is a pretty awesome story, but…

What is even awesome-er, is the neighboring island of Oahu has the same crickets, with the same problem, that also independently evolved flatter wings unsuitable for chirping, over the same time period as the crickets on Kauai! This evidence was brought about by genetic testing that showed:  “the flatwings are caused by a mutation on a single gene, somewhere on the X chromosome. But both mutations arose independently! So the same mutation, flatter wings, happened on both islands, roughly at the same time, in two different populations, in differing area of the genome.”

Absolutely fucking incredible.

Get the full story here: http://phenomena.nationalgeographic.com/2014/05/29/the-silence-of-the-crickets-the-silence-of-the-crickets/

EDIT: Geez, I’m slow, my excuse is I was just on my first cup of joe when I posted this story…I get it now why the original post’s title was duplicated, 2 cases of mutations, on 2 neighboring islands…doh.

Also, I hate it when my attempts at posting links fail to work. I suppose a copy and paste will get you there. In the meantime anyone have link posting tips?

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8 thoughts on “A Case Of Convergent Evolution, Oh My!

  1. Absolutely incredible.

    • I know!

      My mind was blown this morning. A huge case for evolution. A huge hit for creationists. A win win.

      I expect the slimy slugs will find a way to slither around the problem… The 3 “I’s” Sigh, deny, and lie.

  2. It is an amazing story, but I think one must be careful to not conclude that the evolutionary mechanism is convergent, only that survival pressures in both case allowed for the same mutation to occur. It could also be that given the same set of conditions another alternative to defending against the flies might have been a harder exoskeleton. Because there are also plenty of example of species that have been separated and didn’t develop the same adaptation even if it would have been advantageous. If a species is still able to thrive without adaptation because they don’t face the same environmental pressure, as a similar species in a different reason, then they won’t need to change in order to survive. Those in favor of intelligent design would love to prove that evolution is a convergent process because then it means that evolution has a specific goal which was to lead to a complex intelligent being like us, so thus there must have been a divine guiding hand to complete that plan. This is an argument I’ve seen before and they didn’t even have lovely examples like this to make their point.

    • But really fucking amazing though…really! I am glad you shared this.

    • I see your point, but…does not the indication that the mutations occurred in a different area of the genome indicate convergence?

      I lifted this definition from an online dictionary I am fond of (http://www.thefreedictionary.com/): “Biology The adaptive evolution of superficially similar structures, such as the wings of birds and insects, in unrelated species subjected to similar environments. Also called convergent evolution.”

      I suppose technically the crickets and the parasitic flies were of the same species, however the wing changes in both populations occurred at different points in the genome. Granted my understanding of evolution might not pass the high school exit exam, but I am trying!

      Had the evolved trait occurred in the exact same spot of the genome perhaps the creationuts would have a point of contention…if a “designer” was going to go through the trouble to help out the crickets (I thought humans were the preferred species?) Why would he/sh/it take two different pathways?

      To me, the fact that evolution has been caught red handed, makes the claim that evolution is some “big atheistic lie”, has been refuted. I know it has been refuted many times over already with no convergence (converts from creationist deniers to believing what the facts are telling us) occuring in creationist circles, but a guy can hope.

      • Perhaps I didn’t do a very good job of explaining what I mean. What we have here perhaps more importantly is an example of natural selection at work. Whether it happened on one or two islands it demonstrates that the crickets who made a lot of chirping where dying from the parasitic fly, and the crickets who were born with a mutation that made the chirp more quietly or not at all were surviving. Thus their DNA was the one to get passed on.

        Now the fact that this happened on two separate islands is an example of convergent evolution.

        My point is that because convergent evolution happens, does not mean that evolution is convergent. Evidence demonstrates that evolution is divergent as a whole. Meaning this: Just because their is an evolutionary advantage to some trait, there is no guarantee a species will develop that trait. I am sure there are plenty of examples but the one that I read about in one of Dawkins book was about the same species of woodpecker in two different location. Before mutation the woodpecker extracted insects from the trees of only dead trees. But in one location the woodpecker must have faced some additional environmental pressure and developed a different beak (I don’t remember if it was harder or a different shape) to extract insects from living trees as well. This made it much easier for the woodpecker to eat and thus survive. In the other location the woodpecker did not develop that adaptation. It was doing just fine. However if it gained this adaptation it would have an even easier life. So why wouldn’t it develop the adaptation? Quite simply there is no reason to.

        Those in favor of intelligent design would argue that evolution as a process is convergent, that every species would tend towards the same adaptations that increase their chance of survival. That everything sort of tends toward the top of a pyramid. In general the diversification of species makes it pretty clear that the process as a whole is not convergent. Species differentiate from similar root species as they get displaced geographically or other environmental pressures occur. There may also be several ways to fight of the same environmental pressure. Some may develop wings to get away from predators, some may run faster, develop venoms, etc. So convergent evolution is a real thing and it happens, but it does not mean that the whole mechanism is convergent.

        So in answer to your question about how a religious person might twist this to their argument is to say, here is an example of convergent evolution, indicating that the whole process must therefore be convergent. They would be wrong of course, as all their arguments are, but that is probably what they would do. Most wouldn’t even be clever enough to know that much about evolution to make this argument they would just ignore this and quote you something from the bible. lol

      • Thanks for the concise explanation Swarn. Yes I see exactly what you are saying, that while biodiversified convergence occurs, it does not indicate or mean in any way, that it has to. Or that it would happen in the exact same way.

        It seems to me that for some creationists to have begun to argue that evolution can only happen as “X”, that they have pretty much started admitting that something they used to deny vehemently does in fact, happen. They just have really idiotic arguments, lacking any kind of evidence based facts, and are trying there best to insert their gods into the undeniable existence of evolution. I suppose CD and hypocrisy know no bounds…nevermind those creationists that declare evoltuion and science as coming “from the pits of hell”

        If the gods are there tinkering with the crickets, perhaps we could ask for an interview. Hey, wait a minute, does this mean that god is a parasitic fly?

        …oh yes, the argument by bible quote. Those are always convincing…pardon me while I recover from a severe eye roll.

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