Island bugs abandon the power to fly, and Darwin knew why

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December 10 (UPI) – Although the majority of the world’s insects are regularly airborne, a sizable minority have given up that ability. On the small islands halfway between Antarctica and Australia, almost all insects have given up flight.

Like some other evolutionary phenomena, Charles Darwin had a theory as to why insects eventually forbid to flee.

New research published this week in the journal Proceedings of the Royal Society B suggests he got it right.

“”[Darwin] and the famous botanist Joseph Hooker had a substantial argument as to why this is happening. Darwin’s position was deceptively simple, “Rachel Leihy said in a press release.

“When you fly, you are blown out to sea. Those who stay on land to produce the next generation are the ones who fly the least, and ultimately evolution does the rest. Voilà,” said Leihy, PhD student at the Monash University School of Biological Sciences.

Like Hooker, many scientists have expressed doubts about the theory. Few, however, have studied insect diversity on sub-Antarctic islands, where howling winds are the norm.

“If Darwin really got it wrong, the wind would in no way explain why so many insects have lost their ability to fly on these islands,” Leihy said.

For the study, Leihy and her colleague Steven Chown used a large new dataset on insects from sub-Antarctic and Arctic islands to investigate possible explanations for the incapacity to fly.

Leihy and Chown examined fauna inventories, morphological information of the species and environmental variables on 28 of the so-called islands in the Southern Ocean.

They found that insects that developed on the islands were more incapable of flying than those that were recently introduced. They also found that insects were more likely to forego flight in the windiest environment.

Constantly strong winds make the flight difficult and are physiologically demanding. Insects save their evolutionary capital and invest in reproduction instead of wings and wing muscles.

“It is noteworthy that after 160 years, Darwin’s ideas continue to bring insights into ecology,” said Leihy, lead author of the new paper.