Take a walk through the Great Smoky mountains in the eastern US on a summer鈥檚 evening and you might come across a tree decked with hundreds of lights, all flashing in sync. This is not an unseasonal Christmas tree but an abode of the region鈥檚 renowned . Now we may know why they put on this impressive light show.
Different species of firefly flash different patterns, and females respond to male flashing with a light pattern of their own. That suggests that the synchronous flashing allows females to spot males of the same species, but no one had put the fireflies to the test to find out for sure.
To do this, of the University of Connecticut in Storrs and at Georgia Southern University in Statesboro turned to LEDs. They put female synchronous fireflies () in a Petri dish surrounded by green LEDs, and flashed the lights in the same pattern used by male fireflies.
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The females responded with their signature pattern 82聽per cent of the time 鈥� but only if the LEDs were synchronised. When the lights did not flash in unison, female response dropped to 10聽per cent or less.
Noisy pick-up joint
If the male fireflies all flashed in the dark in their own time, it would be difficult to distinguish the patterns, says Moiseff. In that situation, he says, 鈥測ou can鈥檛 pick out the rhythm from any single [species]. It鈥檚 just noise.鈥�
But if a group of fireflies flash in sync () their pattern will override background 鈥渘oise鈥�.
The researchers emphasise that their findings don鈥檛 rule out other theories for why 笔.听肠补谤辞濒颈苍耻蝉 flash in sync. Another possibility is that the synchronised flashing creates dark periods during which females can respond.
Journal reference: , DOI: 10.1126/science.1190421
