Evolution sparks silence of the crickets

[Judi Lynn]

Evolution sparks silence of the crickets

Males on two Hawaiian islands simultaneously went mute in just a few years to avoid parasite.
Katia Moskvitch

29 May 2014

Populations of a male cricket on different Hawaiian islands have lost their ability to chirp as a result of separate, but simultaneous, evolutionary adaptations to their wings. The changes, which allow the insects to avoid attracting a parasitic fly, occurred independently over just 20 generations and are visible to the human eye, a study reveals.

The findings could help to shed light on the earliest stages of convergent evolution — when separate groups or populations independently evolve similar adaptations in response to natural selection.

Male field crickets (Teleogryllus oceanicus) are known for their chirping sound, which is produced by scraping their wings across one another. The wings’ veins form special structures that make the vibrations that we hear as the crickets’ song. “The mechanism is like rubbing your fingernail on the file of a comb,” says study leader and evolutionary biologist Nathan Bailey of the University of St Andrews, UK.

The nightly serenades lure in females and facilitate reproduction — but unfortunately for the males in Hawaii, the chirping also attracts a deadly parasitic fly, Ormia ochracea. The fly larvae burrow into the cricket and grow inside, killing the host when they emerge a week or so later.

More:
http://www.nature.com/news/evolution-sparks-silence-of-the-crickets-1.15323

[BlueStreak]

1. The same process that gives us super-bacteria

The genetic diversity is always there. That did not arise in 20 generations. What happened in the 20 generations is that the parasite gained traction, which gave the edge to the crickets that don't attract the parasite.

This process goes on all the time. It is exactly the same thing as bacteria that become resistant to anti-biotics. Here is a site that talks about that:
http://evolution.berkeley.edu/evolibrary/article/medicine_03

It is amazing that the religious whack jobs at the Creation Museum (and elsewhere) aren't challenged more vigorously. In the infamous Bill Nye debate, Hamm kept referring to the idea that the Ark didn't have to accommodate every species -- it only had to make space for "kinds". But that means, obviously, that after these "kinds" left the ark, they would have to EVOLVE to the species we have today, thus proving that evolution is the way of the world. I don't think Nye ever pointed out this most basic of fallacies, and the "kinds" nonsense continues unchallenged.

[DetlefK]

2. I noticed the same about mosquitos over the last years.

About 10 years ago, the mosquitos in my area used to make a very particular high-pitched humming-sound. If I heard one inside my bedroom, I got up to look for it and then I killed it. But today, they fly in silence. I don't know when exactly this occured or how fast or what's responsible for it, but to me that's my personal proof of evolution.

[Thor_MN]

3. Personally, I'd ask a young person about that.

As we age, we tend to lose hearing at higher frequencies. The hairs in our inner ears that respond to higher frequencies are smaller and finer than those that respond to lower frequencies and are thus more fragile. A loud enough sound will damage them and while there is some regrowth, a lifetime of damage starts to pile up, starting at the higher frequencies.

I don't mean to rule out the silence of the mosquitos ( there's a best selling horror story in there somewhere), but any given person's ability to hear a mosquito whine will diminish with age.

[DetlefK]

4. "Can you hear the mosquitos, Clarice?"

I'm in my early 30s and the pitch is at about 15 kHz. I still should be able to hear that.

[Thor_MN]

5. I'm early 50's and can't hear the ring tone that my nephews can.

I guess by definition, you are a young person to me...

Stealth mosquitos... I don't know that I'm going to sleep tonight...