Natures wonders: painted lady butterflies in S. America (Introduction)

by David Turell , Tuesday, June 25, 2024, 17:38 (83 days ago) @ David Turell

Just discovered:

https://phys.org/news/2024-06-world-km-transatlantic-flight-lady.html

"In October 2013, Gerard Talavera, a researcher from the Botanical Institute of Barcelona at CSIC, made a surprising discovery of painted lady butterflies on the Atlantic beaches of French Guiana—a species not typically found in South America. This unusual sighting prompted an international study to investigate the origin of these butterflies.

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"First, the research team reconstructed wind trajectories for the period preceding the arrival of these butterflies in October 2013. They found exceptionally favorable wind conditions that could support a transatlantic crossing from western Africa, opening the possibility that those individuals might have flown across the entire ocean.

"After sequencing the genomes of these individuals and analyzing them in comparison to populations globally, researchers discovered that the butterflies had a closer genetic relatedness to African and European populations. This result eliminated the likelihood of these individuals coming from North America, thereby reinforcing the hypothesis of an oceanic journey.

"Researchers leveraged a unique combination of next-generation molecular techniques. They sequenced the DNA of pollen grains carried by these butterflies. They identified two species of plants that only grow in tropical Africa indicating that the butterflies nectared on African flowers before engaging into their transatlantic journey.

"They analyzed hydrogen and strontium isotopes in the butterflies' wings, a chemical signal that acts as a "fingerprint" of the region of natal origin. Combining isotopes with a model of habitat suitability for larval growth revealed potential natal origin in western Europe, possibly France, Ireland, the United Kingdom, or Portugal.

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"The researchers assessed the viability of a transatlantic flight by analyzing the energy expenditure for the journey. They predicted that the flight over the ocean, lasting five to eight days without stops, was feasible due to advantageous wind conditions.

"'The butterflies could only have completed this flight using a strategy alternating between active flight, which is costly energetically, and gliding the wind. We estimate that without wind, the butterflies could have flown a maximum of 780 km before consuming all their fat and, therefore, their energy," says Eric Toro-Delgado, one of the article's co-authors. (my bold)

"The Saharan air layer is emphasized by researchers as a significant aerial route for dispersion. These wind currents are known to transport large amounts of Saharan dust from Africa to America, fertilizing the Amazon. This study now shows that these air currents are capable of transporting living organisms.

"This finding indicates that natural aerial corridors connecting continents may exist, potentially facilitating the dispersal of species on a much larger scale than previously imagined."

Comment: a beautifully thorough study. Painted ladies normally migrate from Europe to Africa, presented here: 2018-06-13, 23:35. A tiny brain makes aerodynamic adjustments to make the trip.