Photo: Durotriges (flickr)
When I say “cricket,” what’s the first thing that comes to your mind? Chirping, right?
Whether you find chirping musical or annoying, cricket chirps aren’t intended for us at all, but are the strategy by which male crickets attract female mates.
For male crickets on the Hawaiian island Kauai, however, there’s a problem. These flirtatious chirps attract a second respondent, a fly that deposits maggots onto the caller’s back. These maggots are bad news because they’re lethally parasitic. They burrow into the cricket, eat him alive, and crawl out a week later.
What’s a cricket to do? Well, in the span of just a few years, about twenty generations of crickets, male crickets on Kauai have evolved from boisterous to silent. A mutation on the single X chromosome of male crickets has produced a population of males unable to call for mates. The mute males have similar wings to females, which lack the noise producing structure.
This rapid evolution has been successful so far. The cricket population has bounced back from a major decline. It’s successful, because these mute males rely on the few males who are still able to chirp. They hang around to mate with females that respond to their competitor’s call. Though females are typically choosy about whom they mate with, requiring a courtship song upon arrival, it seems that Kauaian females too may have evolved. They’ll mate without a song.
However, what will happen in the future as even fewer males are able to call? Will they be able to attract and mate with females? Will chirping again become valuable, shifting the tide of evolution once more? Only time will tell.