Take a walk through the Great Smoky mountains in the western US on a summer's 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's renowned synchronising fireflies. 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, Andrew Moiseff of the University of Connecticut in Storrs and Jonathan Copeland at the State University of New York at Stony Brook turned to LEDs. They put female synchronous fireflies (Photinus carolinus) in a Petri dish surrounded by green LEDs, and flashed the lights in the same pattern used by male fireflies.
The females responded with their signature pattern 82 per cent of the time – but only if the LEDs were synchronised. When the lights did not flash in unison, female response dropped to 10 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, "you can't pick out the rhythm from any single [species]. It's just noise."
But if a group of fireflies flash in sync (click here to see video) their pattern will override background "noise".
The researchers emphasise that their findings don't rule out other theories for why P. carolinus flash in sync. Another possibility is that the synchronised flashing creates dark periods during which females can respond.
0 comments:
Post a Comment