Teleogryllus oceanicus flatwing and wild-type wing morphsWIKIMEDIA, NATHAN BAILEYAs the sun sets over the grassy lawns that traverse the Hawaiian island of Kauai, the chirping crickets do not perform their usual dusk chorus. Instead, they are ominously quiet: in Kauai and neighboring Oahu, field crickets (Teleogryllus oceanicus) have acquired a wing mutation that silences them. It also saves them from being eaten inside out while still alive.
The field crickets in Kauai offer a live demonstration evolution in action. In 1991, cricket numbers crashed as parasitoid flies (Ormia ochracea) located male calling crickets by sound and made them into live incubators for their eggs. The parasitic larvae would hatch and eat their cricket hosts from the inside out. Twelve years and 20 generations later, the cricket population bounced back, dominated by males with a wing mutation that rendered them silent. Male crickets on Oahu followed suit within two years; eventually, silent males outnumbered their chirping peers.
Sonia Pascoal from Scotland’s University of St Andrews and her colleagues sought to investigate how the mutation in the wing for silent males, called “flatwing,” might have spread from Kauai to Oahu. Two possibilities stood out: ...
