How to stand out to a mate - Flash colour of Photinus fireflies maximizes signal contrast against ambient light
During twilight, flying male Photinus fireflies flash in search for conspecific females, which sit on the vegetation below and flash back in response. However, before darkness sets in, the green vegetation in the habitat makes the detection of flashes more difficult. Twilight active fireflies tend to emit more yellow flashes than nocturnal fireflies and it has been proposed that firefly flash…
Around dusk, male Photinus fireflies engage in a search for females of the same species. The females rest on vegetation below and respond by flashing back. However, as darkness descends, the green foliage in the environment makes it harder for the insects to spot each other's flashes. Twilight-active fireflies emit more yellow flashes than those active at night, leading researchers to propose that the firefly flash colour evolved to improve contrast between the signal and background.
While there is indirect evidence supporting this contrast hypothesis, a study has now directly tested it by recording ambient light spectra in three habitats during the daily flash activity of two species: Photinus pyralis and P. australis. The study aimed to compare these ambient light spectra with the male flash spectra of the two species and test whether the firefly's flash colour maximizes contrast with the background during peak activity.
The research found that the male flash spectra fall into a gap in the ambient light spectrum that opens up during the species' peak flashing period. This gap effectively enhances the visual contrast between male flashes and their background, making the males more visible to potential mates.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
