What Led To The Silence Of The Crickets On Kauai?

The silence of the lambs was caused by hungry Hannibal Lecter hosting a dinner party, but what's causing the silence of the crickets on the island of Kauai?

A researcher named Marlene Zuk first noticed the silence of the crickets in 2003, a very noticeable silence compared to when she first started studying the crickets on the island back in 1991, and she knew something was wrong because she continued to see the crickets everywhere despite their vow of silence.

After dissecting a few of the insects she discovered the source of their silence- the male crickets had developed flat wings that didn’t make a sound to avoid being eaten by a parasitic fly.

Here’s more on this interesting evolution to silence:

Zuk’s team discovered that the crickets were targeted by a parasitic fly, whose larvae burrow inside them and devour them alive. The flies finds the crickets by listening out for their songs and they’re so effective that, in the early 90s, they had parasitised a third of the males. In 2002, the cricket population had fallen dramatically, and Zuk thought that they were done for.

But the silent males escaped the attention of the fly. As they bred and spread, they carried the flatwing mutation with them. By 2003, the cricket population had rebounded. And in fewer than 20 generations, they had gone from almost all-singing to almost all-silent. The crickets have become a classic textbook example of rapid evolution.

-Via National Geographic


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The type of experiment you've proposed has already been done and is on going with more typical model organisms like the fruit fly and E. coli. I'm not a biologist though, and can't quickly recall a variety of such work off the top of my head, and have unfortunately forgotten a lot of detail from conversations from a friend who actually did genetics research on D. melanogaster. But the gist of the conversations was that there are experiments now on the grad student level that show drastic changes in gradually changed environments, to the point the population at the end would quickly die off if put back into the original environment. These included experiments that would create two separate populations, develop tolerance to some different environmental difficulties, then recombine to find that the populations had a preference for mating withing their own populations and not cross-breeding.

A particularly famous experiment that had been in the news a couple years ago was Lenski's long term E. coli experiment, that has breed 50k+ generations of E. coli. A couple years ago. A couple years ago, some of the E. coli in the experiment appeared to suddenly evolved the ability to aerobically metabolize citrate. This was a big deal, as that ability is not present in E. coli and is used as a test to separate Escherichia from Salmonella. The experiment preserved batches every so many generations, so they can go back and do genetic analysis and rerun some generations. The cumulative change allowing it to live off of citrate in an aerobic environment involved several genetic changes, such that if you go far enough back, it doesn't evolve in a new batch, but at an intermediately point in the history it redevelops because the a particularly difficult change was already made.

As far as grant wordings, I don't think I've ever seen a public grant word such that payment came after results for that particular experiment... however if your experiments end up as a dead end (good or bad) you will need to find something new and interesting for your next grant.
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If I was a professional reviewer and being paid to review such things, I would be tempted to go through the papers myself. If they could prove there weren't any silent crickets at all before the parasite arrived, this would be the first event I've heard about that could truly be called evolution through adaptation (information added to change a species in a novel way) and not specialization through adaptation (information removed to make a species more specialized). As I said, I'm not a creationist, but I find it interesting that the only cases of evolution we can find are of extinct species, even in insects with rapid breeding cycles. Specialization is really easy to find, in contrast.

It's kind of like trying to figure out how life started in the first place. We have some rough ideas of how it could possibly happen, but we can't seem to devise a test that works without us priming the solution with RNA or at least some RNA-related long-chain proteins.

But science is interesting in part because of the things we have yet to find that we are pretty darn certain are still out there. Lack of proof for a theory isn't the same as proof that a theory is false. Though, we've seen our fair share of theories that we were certain of proven false when new evidence or ideas came around.

Proving it, in this case, wouldn't be too difficult, considering they have at least one nearby neighbor species on other islands, and we're talking about an insect rather than a mammal or reptile. They could easily generate millions of the things over many generations (5-10 years, like they suspect was necessary in the real world scenario) and test them to see if any silent crickets naturally occur without the parasite's presence. Then do the same number of generations with the presence of the parasite, and see if silent crickets happen, or something else, like total eradication, or a specialized song that the parasite doesn't like. If they have enough generations and enough total population, it would be enough to say they've scientifically tested the case thoroughly.

The hard part would be figuring out a way to test for silent crickets. As long as that test is trustworthy, it could work. Unfortunately, if the grant is worded in such a way that the researchers only get paid if they don't find silent crickets in the control group, I'd be a little worried the scientists involved would just devise a shoddy test and jump to "Whelp, we didn't find any silent crickets..."
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The wording is vague about whether there were silent ones before the big change, and I couldn't tell if that was because a few examples had been seen before, or that they had not observed any before ~2003 and acknowledging that limited observations may have just missed it previously. Although the species was studied going back into the 90s, because before the appearance of the silent type, a bunch of changes in the songs were observed and being studied as a response to the parasite. There is plenty more information in the papers (which seem to be all open-access of the ones I looked at). I only looked through a couple and probably missed a lot.
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