MEDFORD/SOMERVILLE, Mass. -- A new study by biologists at Tufts University has discovered a dark side lurking behind the magical light shows put on by fireflies each summer. Using both laboratory and field experiments to explore the potential costs of firefly courtship displays, the biologists have uncovered some surprising answers.
The research, to be published in the November 2007 issue of American Naturalist and now available online (http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/521964), revealed that its energetically cheap for fireflies to produce their distinctive flash signals, but that flashier males are more likely to end up on the dinner table.
On summer evenings, male Photinus fireflies lift off into the air to broadcast their bioluminescent flashes in search of females. Females perched in the grass sit and admire passing males and, if they're interested, will flash in response. Previous research on many different firefly species has shown that females respond more readily to males that give longer flashes, as well as those with faster flash rhythms. This female choice favors firefly males that produce more conspicuous flashes.
"Since females so clearly prefer the flashier males, one thing that's been puzzling scientists is what's keeping these males from evolving longer and longer, faster and faster flashes," says Sara Lewis, professor of biology at Tufts and leader of the research team that included postdoctoral researcher William Woods and two undergraduate students. In theory, there might be some hidden costs to more conspicuous flashes, but what are they"
To answer this question, the researchers set out to look at two potential costs of firefly flash signals. First they measured the energy that fireflies expend while they're producing their bioluminescent flashes. In carefully controlled laboratory expe
|Contact: Kim Thurler|