The researchers also found that male cricket populations in Oahu and the Big Island, as well as descendants from eggs collected on Kauai before 2003, continued to show normal wings. Only on Kauai were the mutated wings seen in male crickets in 2003.
"Loss of calling clearly seems to be protecting the male crickets from the deadly fly," Zuk said. "But this protection has a heavy price: the loss of its sexual signal. This is obviously a huge loss for the cricket, akin to, say, finding that all peacocks in a forest have lost their tails. One might ask how then do female crickets locate silent flatwing males?"
Zuk and colleagues propose that on Kauai, the flatwings a term they use to identify male crickets with mutated wings behave as 'satellites' to the few remaining male crickets that can call. By congregating near the callers, the flatwings enable females to find and mate with them.
To test their hypothesis, the biologists performed a field experiment that demonstrated that the flatwings are using the callers as female attractors (for details, see below).
"While we were surprised by the extraordinary speed at which the mutation spread, what is more interesting is that, ordinarily, you would expect such a change in wing morphology to quickly disappear, because males couldn't attract mates," Zuk said. "Instead, the behavior of the flatwings allows them to capitalize on the few callers that remain, and thus escape the fly and still reproduce. This is seeing evolution at work."
Field experiment details:
The researchers performed experimen
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Contact: Iqbal Pittalwala
iqbal@ucr.edu
951-827-6050
University of California - Riverside
22-Sep-2006