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Most insects can fly.
But many species have lost this extraordinary ability, especially on islands.
On the small islands halfway between Antarctica and continents like Australia, almost all insects have done so.
Flies run, moths crawl.
“Of course, Charles Darwin knew about this wing-loss habit of island insects,” says Ph.D. Candidate Rachel Leihy from Monash University School of Biological Sciences.
“He and the famous botanist Joseph Hooker had a significant argument about why this was happening. Darwin’s position was deceptively simple. If you fly you will be driven out to sea. and finally evolution does the rest. Voilà. “
But since Hooker voiced his doubts, so have many other scientists.
In short, they simply said that Darwin was wrong.
Yet almost all of these discussions have ignored the epitome of flight loss – these “sub-Antarctic” islands. They are located in the “Roaring Forties” and “Furious Fifties” and are some of the windiest places in the world.
“If Darwin was really wrong, the wind would in no way explain why so many insects lost their ability to fly on these islands,” Rachel said.
Using a large, new dataset on insects from sub-Antarctic and Arctic islands, Monash University researchers examined every idea proposed to explain flight loss in insects, including the Darwin wind idea.
You report today in the Proceedings of the Royal Society B and show that Darwin was right for this “windiest place of all”. None of the common ideas (like those suggested by Hooker) explain the extent of flight loss in sub-Antarctic insects, but Darwin’s idea does. Even if in a slightly modified form, completely in line with modern ideas about the actual development of flight losses.
Windy conditions make it difficult for insects to fly and are energetically expensive. Therefore, insects no longer invest in flight and its expensive underlying machinery (wings, wing muscles) and divert resources towards reproduction.
“It is noteworthy that even after 160 years, Darwin’s ideas continue to provide insights into ecology,” said Rachel, the paper’s lead author.
Professor Steven Chown, also from the School of Biological Sciences, added that Antarctica is an exceptional laboratory for solving some of the world’s most enduring mysteries and testing some of its key ideas.
Darwin’s handwritten pages from ‘On the Origin of Species’ go online for the first time
More information:
Wind plays an important but not exclusive role in the prevalence of insect flight losses on remote islands, Proceedings of the Royal Society B, rspb.royalsocietypublishing.or… .1098 / rspb.2020.2121 Provided by Monash University
Quote: Charles Darwin was right when asked why insects lose their ability to fly (2020, December 8th), accessed on July 20, 2021 from https://phys.org/news/2020-12-charles-darwin-insects-ability .html
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