Why do flying adult fireflies (family Lampyridae) glow? Years of conjecture by experts seems to have been put to rest by an international team of scientists including representatives of the Czech Advanced Technologies and Research Institute – CATRIN, Palacký University Olomouc, who believe that fireflies use bioluminescence for courtship. They base their conclusions on analyses of a large amount of molecular data and fossil samples from 25-99 million years ago. Their research results have been presented in the Proceedings of the Royal Society B: Biological Sciences, and also mentioned as a scientific matter of interest in the journal Nature.
“While firefly larvae glow to indicate that they are not palatable food, adults probably started using bioluminescence to woo. In fact, we have established that fireflies acquired this ability more than 133 million years ago. Long before their natural enemies, the birds and bats of today, appeared on Earth. The most probable hypothesis is that sexual communication was the reason for the emergence of light in adults,” said one of the authors of the study, Dominik Kusý from CATRIN. Together with the Olomouc scientists, their long-standing partners from several research institutions in the USA participated in the research.
“We were interested in the evolutionary history of fireflies and their luminescent relatives (families Sinopyrophoridae, Phengodidae, Rhagophthalmidae) and click beetles (family Elateridae). We used a large number of genes to reconstruct family relationships. We also examined a new set of fossils, including one from Burmese amber, which dates back to the Mesozoic Cretaceous. Thanks to molecular dating, we were able to determine when and in which evolutionary lineage the ability to bioluminescence in adults arose and, based on this, to infer the possible reason for this evolutionary change,” Kusý explained.
Olomouc scientists have been studying fireflies and their bioluminescence for a long time. Earlier studies, in which they also participated, have identified a glowing relative of fireflies that is strikingly similar to click beetles, thus demonstrating that glowing beetles have been on Earth for about 150 million years.
Bioluminescence, the emission of light by certain organisms, is not only found in fireflies and their close relatives, such as the click beetles. It can also be observed in some species of fish, fungi and invertebrates. It is associated with the presence of luciferin and the enzyme luciferase.