http://news.nationalgeographic.com/news/2006/10/061003-silent-crickets.html
http://evolution.berkeley.edu/evolibrary/news/061201_quietcrickets
http://www.bbc.com/news/science-environment-27592656

Scientists have been studying crickets on the Hawaiian islands for the better part of a decade now, and they've discovered something curious! A species of fly had migrated from the mainland US, and preyed on the crickets by tracking them by their sound, laying eggs on the males that would hatch and devour them several days later. In the 1990's the flies decimated the cricket population, and by 2001 almost all of them had been preyed out! But then, the crickets bounced back, and scientists realized that they'd adapted to camouflage themselves from their predators.

Apparently, the cricket populations have evolved different mutations in the shape of their wings that prevent them from making noise, thereby hiding them from the flies! It's theorized that in the course of traveling from Asia to Hawaii, the cricket populations went through a genetic bottleneck that made such mutations easier and females much less choosy in picking a mate - they don't mind mute partners. :> Since not all of the islands host the flies, and the crickets on those continue to make noise, it's entirely possible that in a century or two the crickets might end up diverging into entirely separate species - scientists have recorded two different mutations on different islands resulting in two completely differently-shaped wings.

Ain't biology interesting?