Scientists have discovered the first evidence of insects crossing an entire ocean – after finding butterflies making a 4,200 kilometer journey across the Atlantic.
Gerard Talaveraevolutionary biologist from the Botanical Institute of Barcelona, made the discovery in French Guiana in 2013 when he spotted a flock of painted butterflies (Vanessa cardui) sat on the sand with torn wings and shot holes.
The discovery puzzled scientists because these tiny species can be found all over the world, but not in South America. Now, after a decade of investigation, scientists have pieced together an answer to how the butterflies got there: They embarked on the first transoceanic flight recorded for an insect.
The researchers published their findings Tuesday (June 25) in the journal The nature of communication.
“We tend to see butterflies as a symbol of the fragility of beauty, but science shows us that they can perform incredible feats,” study co-author Roger Villaresearcher from the Institute of Evolutionary Biology in Barcelona, he said in a statement. “There is still much to discover about their abilities.
Insect migrations are not uncommon, but they are hard to follow. Scientists usually rely on amateur insect watcher records and radar coverage to study insect movements, but these are limited and not always reliable.
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To find out how the painted bowties got to French Guiana, the researchers put together several strands of evidence. They sequenced the genomes of the butterflies, which revealed that they are closely related to populations in Europe and Africa. The team also analyzed the pollen DNA on the 5-centimeter-long insect bodies and identified two plant species that are only found in tropical Africa. In addition, they studied hydrogen and strontium isotopes on butterfly wings and found them to be unique to Western Europe.
Taken together, this evidence ruled out a North American origin for the insects and suggested that their lives began in Africa or Europe.
“Painted butterflies reached South America from West Africa, flying at least 4,200 km over the Atlantic. However, their journey may have been even longer, starting in Europe and crossing three continents, a migration of 7,000 km.” [4,350 miles] or more,” co-author of the study Clement Bataille, a professor of earth and environmental science at the University of Ottawa in Canada, said in a statement. “That’s an extraordinary feat for such a small insect.”
Painted lady butterflies are already known migrate up to 9,000 miles (14,500 km) between Europe and Africa, including crossing the unforgiving expanse of the Sahara.
But this trip is done with overnight stops to rest and refuel. To get from West Africa to French Guiana, the butterflies would have to fly for up to eight days without rest.
To solve this part of the mystery, scientists analyzed the wind currents that rise from the Sahara and blow dust from Africa to the Americas. They discovered that by gliding along these aerial highways, butterflies can complete their remarkable journey.
“Butterflies could only complete this flight using a strategy of alternating between minimal effort to avoid falling into the sea, facilitated by upwelling winds, and active flight, which requires more energy,” study co-author. Eric Toro-Delgado, a doctoral student at the Institute of Evolutionary Biology, said in a statement. “We estimate that without the wind the butterflies could fly a maximum of 780 km [485 miles] before they use up all their fat and therefore energy.”
The finding highlights the insect’s ability to cross vast distances in ways scientists hadn’t previously considered.
“This discovery opens new perspectives on the ability of insects to disperse over long distances, even across seas and oceans. It is possible that we are underestimating the frequency and impact of these movements on our ecosystems,” said Talavera, lead author of the study. declaration. “Throughout history, migration phenomena have been important in defining the distribution of species we see today.”