Scientists: European butterflies travel 4,200 km to reach South America

Scientists: European butterflies travel 4,200 km to reach South America

Nature magazine said that burdock butterflies traveled 4,200 kilometers to reach South America. Scientists were amazed at the ability of these small insects to travel great distances over the ocean.

South America is the only continent where this type of butterfly is not found.

What do the famous Russian explorer Fyodor Konyukhov and burdock butterflies have in common? They are both able to cross the Atlantic Ocean in record time. To do this, Fyodor Konyukhov needed 46 days and a specially designed 7-meter rowing boat built for him in England, but who would have thought that fragile butterflies weighing one gram would cover thousands of kilometers on the water?

However, this is a proven fact. South America was the only continent where these butterflies were not found. However, a group of biologists found these butterflies on the coast of French Guiana, a French territory in South America.

“We caught many butterflies on the beach, perhaps after a long journey across the ocean, based on their damaged wings and their behavior on the sand,” the study authors said. “To determine the origin of the burdock found, we compared its genome with samples from Europe, Africa and North America. The result ruled out its North American origin, so She traveled no less than 4,200 kilometers, which is the distance that separates Africa and French Guiana.

To be more confident, the biologists studied the stable isotopes of hydrogen and strontium in the butterfly wings. The ratio of isotopes is unique, taking into account the location where the butterflies grew and emerged from the cocoon. By comparing the data to a map of isotope distribution, the researchers determined the home of the migrating insects: either Western Europe (Portugal, France, Ireland and the UK) or West Africa (Mali and coastal areas of Senegal and Guinea-Bissau). The butterflies could have started out in Europe, then migrated to Africa, and only then pushed on to South America. It turned out that they had traveled not 4,200 kilometres, but at least 7,000 kilometres.

But how did they get there? Scientists estimate that without the help of the wind, the butterflies could not travel more than 780 kilometers. So, they were helped by the easterly winds, which annually carry millions of tons of dust from Africa to America across the Atlantic Ocean.

Computer modeling showed that, taking into account an average wind speed of 7.47 meters per second, the butterflies could fly to South America in 5-8 days if they used passive flight, i.e. flapping their wings only to stay in the airflow. In this case, the fat reserves at the moment of the flight must be at least 13.7% of the butterfly's body weight. Otherwise, it would not have enough energy and would die in the ocean.

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