To prevent getting lost, the elevator goes directly to the safety island to report Liu Yadong A
Source: Bringing Science Home
Author: Liu Liuqi
In many literary and artistic works, butterflies are the representative of "fragile beauty".
For example, Liang Shanbo and Zhu Yingtai failed to achieve positive results, and finally turned into a pair of colorful butterflies and flew away from the world. In the love song, people also use butterflies to comfort their inner regrets, singing "Just like a butterfly can't fly in the sea, no one can bear to blame".
图源:Peter Kuper
However, an article in the journal Nature Communications shattered people's stereotypes: butterflies can really fly across the sea! After years of analysis, researchers have finally confirmed that a flock of small red butterflies once flew more than 4,200 kilometers non-stop, crossing the Atlantic Ocean from Europe and Africa to South America.
Little Red Butterfly|Source: Gerard · Talavilla
This shocking and romantic creature tracking can be traced back to one day 11 years ago.
Early one morning in late October 2013, entomologist Gerard · Talavilla was walking by the sea in French Guiana. Suddenly, he noticed about 10 little red butterflies perched on the beach not far away.
The small red butterflies are one of the most widely distributed butterfly species in the world, but their occurrence in South America is rarely recorded, an anomaly that immediately alarmed Gerald.
The location of French Guiana on the world map (it and Guyana are two countries)|Source: free world map
Getting closer, Gerald noticed that the butterflies had wrinkled wings full of holes, and they looked very tired and had no strength to fly, so they could only "jump" and move. Gerald's instincts told him that the little red butterflies did not fly from North America along land, but most likely from Europe or Africa across the Atlantic.
In fact, there is a consensus in the entomological community that the little red butterfly has the ability to migrate long distances. In Europe and Africa, some small red butterflies fly from the southern Sahara Desert to the Arctic Circle in the spring and back in the fall, covering a distance of 14,500 kilometres round trip, well over the more than 4,000 kilometres across the Atlantic.
The migration direction of the small red butterfly between Europe and Africa, red is the northbound route in spring, and blue is the southbound route in autumn|Source: Wildlife Trusts
It's just that the regular migration route of the little red butterfly is mostly accompanied by land, and you can stop and rest when you are tired, and you can suck nectar when you are hungry. For these little ones who weigh only about 1 gram, is it really possible to fly over the vast ocean in one breath?
Since that unexpected encounter on the beach, Gerrard has been trying to test his conjecture for more than 10 years. This is not an easy task, as butterflies are too small and fragile to install radio trackers on them, and radar systems can only monitor specific areas.
Fortunately, Gerard and his colleagues brainstormed and finally used three methods to prove that the group of little red butterflies had indeed crossed the Atlantic.
Gerard Talavera, at the Botanical Research Institute of Barcelona· Source: Internet
First, they adopted "DNA barcoding" technology. A DNA barcode is a sequence of specific DNA fragments that possess enough variability to determine species identity. When an unrecognizable creature is found, researchers can trace its DNA barcode and then compare it with a barcode in an international database to confirm its identity.
Gerald and his colleagues found that the little red butterflies were stained with pollen from the nectar harvesting process, and they traced the DNA barcode of the pollen. The pollen was found to come from several shrubs in West Africa. The flowering season for these shrubs is between August and November, coinciding with the appearance of butterflies on the beach.
DNA barcoding technology has also made a lot of contributions to food traceability, and the journal Science China: Life Science has published an article in which researchers used this technology to find that 70% of the yak jerky raw materials on the market are not yaks|Source: wikipedia
In addition to pollen, researchers have also sequenced the genomes of butterflies to track their lineage. It was found that the butterflies had African-European roots, ruling out the possibility that they flew from North America.
To make the results more reliable, Gerald also used an "isotope tracer" method to determine where the butterflies were born.
There are differences in the ratio of stable isotopes in water, soil, and vegetation in different regions. As animals grow, they ingest these isotopes from the environment and accumulate in tissues such as teeth, bones, and hair. By examining the isotopes in the wings of butterflies, the researchers could see where the plants they ate during their caterpillar period were distributed.
小红蛱蝶的幼虫|图源:wikipedia
The results of isotope tracing are similar to DNA barcoding, and the plants that butterflies eat in their larval stage are distributed in West Africa, North Africa or Western Europe, indicating that these butterflies were born in these regions.
"This is a wonderful biological reconnaissance work, and Dr. Gerald's forensic peeling back is the first time that humans have demonstrated that butterflies, and even insects, can fly across oceans." David · Roman, an evolutionary ecologist at the City College of New York, commented on the media.
小红蛱蝶的蛹|图源：wikipedia
So why did this group of little red butterflies fly to South America?
Gerald speculated that they may have been flying south along a traditional migration route before being blown to the surface by high winds. In order not to fall into the water, the little red butterfly can only fly forward until it sees land.
Gerald speculated that this group of small red butterflies flew for about 5 to 8 days (the picture shows the monarch butterfly)|Source: Internet
Entomologists believe that the maximum distance of a butterfly in a single flight is about 780 kilometers, and the reason why these little red butterflies were able to complete such a great journey is due to the strong east wind and the strong survival instinct of the creatures.
It is truly shocking that a group of creatures weighing only 1 gram, with a wingspan of about 5 centimeters and a brain the size of a pinpoint, can overcome the vast ocean.
Butterflies can fly across the sea, and perhaps there are more wonders of nature waiting for us to discover|Source: wikipedia
Of course, the innovative tracking methods of Gerald's team have also brought inspiration to the scientific research community and opened up new ideas for monitoring insect migration.
Resources:
[1]https://www.nytimes.com/2024/06/25/science/butterflies-ocean-migration.html
[2]https://www.usatoday.com/story/news/nation/2024/07/13/attract-painted-lady-butterflies-to-garden/74370567007/
[3]https://www.cnn.com/2024/07/01/science/painted-lady-butterfly-cross-oceans-scn/index.html
[4] https://www.cas.cn/kj/201603/t20160318_4549877.shtml
[5]https://butterfly-conservation.org/news-and-blog/painted-lady-migration-secrets-revealed