Evolution in reverse: insects recover lost ‘wings’

The extravagant headgear of small bugs called treehoppers are in fact wing-like appendages that grew back 200 million years after evolution had supposedly cast them aside, according to a study published Thursday in Nature. That’s probably shocking news if you are an entomologist, and challenges some very basic ideas about what makes an insect an insect, the researchers said. The thorax of all insects is by definition divided into three segments, each with a pair of legs.

In most orders, there are also two pairs of wings, one on the middle segment of the thorax and another at the rear. Other orders such as flies and mosquitoes have only one set of wings, at the rear, and a few — most ants, for example — have no wings at all. But no insects today have functional flappers in the first segment next to the head. Their forebear, however, did.

“Primitive insects 350 million years ago had wings on all of their body segments,” said Benjamin Prud’homme, a researcher at the Development Biology Institute of Marseille-Luminy in France and lead author of the study.

“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.”

Over the next 100 million years, he explained, wings on the first segment of the thorax and the abdomen dropped away entirely. But then, some 50 million years ago, something strange happened to the cicada-like tree hoppers: they once again sprouted wing-like structures from the top of the first segment of the thorax.

via Evolution in reverse: insects recover lost ‘wings’.

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One Response to Evolution in reverse: insects recover lost ‘wings’

  1. alfy says:

    A lot of developmental biology is to do with “potentialities”. It is just possible that all modern insects still have the “potentiality” for a wing on every segment. More likely is that a “potentiality” for having a pair of wings on each thoracic segment exists.

    Whether these “potentialities” are realised depends on natural selection. Wings on every segment would seriously disadvantage a modern flying insect. However, it may be that in the case of these treehoppers there is some advantage in having the development of rudimentary wings in the pre-thorax. As the “potentiality” has been realised in this case, more research is needed to find a selective advantage.

    This is not really “evolution in reverse” but a rather surprising flowering of a ancient “potentiality”. In human beings, two nipples are the norm, for men and women. However, we have the “potentiality” for developing a whole row on either side, just like a piggy-wig or a doggie. Some people do develop what are called “supernumery nipples”, but as these do not present a major selective disadvantage they still exist within the human inheritance. It is only in witch-fearing societies that SNs could lead to your immediate demise.

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