Researchers have just identified an insect that apparently regained its wings, after having evolved to shed them more than 200 million years ago. The extravagant headgear on small cicada-like bugs called treehoppers was established to be a pair of wing-like appendages, experts say.
The new discovery is very interesting, as it puts evolution and the very definition of an insect to the test, say entomologists. Details of the research appear in the May 5 issue of the top journal Nature.
In the distant past, more than 350 million years ago, insects were very different than they are today. For starters, they had wings on all segments of their bodies, which their modern descendants do not.
Insects today are divided into three body segments, and most of them only have wings on the middle and bottom ones. Some species only carry wings on the end segment (such as mosquitoes), whereas others, including ants and spiders, have none at all.
However, there are no insect species living today that have wings on the uppermost part of their bodies, where the head is located. But the fossil record reveals that all of their ancestors did, experts explains.
“Primitive insects 350 million years ago had wings on all of their body segments. We don't know if they were all for flight, but we do know – from fossil records – that these wing-like structures were present on each and every body segment,” explains lead study author Benjamin Prud'homme.
The expert, who is a researcher at the Development Biology Institute of Marseille-Luminy, in France, reveals that the next 100 million years marked a time when insect lost the wings on their first segments.
But, by 50 million years ago, cicada-like treehoppers had already begun evolving them anew. Wing-like structures suddenly began appearing on the uppermost segment of their bodies, Daily Galaxy
reports. The reason why this happened is still a mystery.
For a very long time, experts were convinced that the structures these insects were developing on their heads were nothing by armor-like structures produced by their exoskeleton, similar to the ones some dinosaurs had for the same reason.
In-depth studies on how treehoppers evolved demonstrated that the structures spawned from buds that were articulated like wings. In most cases, the proto-wings fused together during development.
“This is the only known example of a modern insect that has grown a third pair of wings. It is a modification of the basic body plan of insects,” Prud'homme explains in a phone interview.
“This extra pair of wings was not needed for flight, but nor did it prevent it. So it became raw material for evolution to play with,” the expert says. What remains interesting still is the fact that genetic factors prevented the development of frontal wings for as long as 200 million years.
“How development abilities can be lost or silenced over millions of years, only to be redeployed to contribute to the evolution of a complex and beautiful appendage,” comments Indiana University professor Armin Moczek.