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Scientists solve how a bird unable to fly, the smallest in the world, ended up in an ancient volcano lost in the middle of the Atlantic.
The island Inaccessible, an extinct volcano just 14 square kilometres, emerges as a lone rock in the middle of the South Atlantic. The nearest piece of land is located about 45 kilometres away. It is also the island of Tristán de Acuña, the inhabited place furthest from any other inhabited planet. In this archipelago belonging to the United Kingdom, everything is extreme. The nearest continental coast is 2,810 kilometres away in South Africa.
It is not strange that the Inaccessible does not have a permanent population. Its cliffs of 300 meters are too uncomfortable to stay in them and stories are told of sailors who could not land or move beyond their beaches, probably the reason for their legendary name. However, there is a creature that has found earthly paradise on the rock. It is the Inaccessible Island rail (Atlantisia rogersi), the smallest non-flying bird in the world. How this fragile bird, incapable of flapping its wings, got there is a mystery that has brought scientists to their heads for decades.
The Atlantisia rogersi is endemic and can only be found on that island. There it has no natural enemies and runs calmly like a small rodent among the vegetation. Almost a hundred years ago, the British ornithologist Percy Lowe concluded that the inability to fly of this bird was a very old trait and that it colonized the Inaccessible on foot through tracts of land and continents that then disappeared into the depths of the ocean. That’s why the name of Atlantisia, for Atlantis. But the theory turned out to be wrong.
Biologists from the University of Lund (Sweden) analyzed the DNA of the bird using modern sequencing techniques. In this way, the researchers were able to determine that the closest living relatives of the bird at present are the blackish burrito that inhabits the pastures of South America and the redfish that are found in both South America and the North. Probably also has a relative in the Galapagos.
“It seems that these birds are extremely good at colonizing new remote locations and adapting to different environments. In spite of the great distances, the environments can be similar and, through the convergent evolution, the distant relatives can also come to resemble », says the biologist Martin Stervander, co-author of the study.
From South America
“The fact that Lowe’s theory was incorrect was not a surprise. By using the DNA, we can prove that the ancestors of the bird flew to the Inaccessible Island from South America about 1.5 million years ago, “says Stervander.
“The bird has not had natural enemies on the island and has not needed to fly to escape predators. Therefore, its ability to fly has been reduced and, ultimately, it has been lost through natural selection and evolution for thousands of years, “he explains. Not being able to fly means that the little bird does not waste energy on something that is unnecessary to survive and spread.
“Our discovery focuses on the importance of continuing to prevent enemies from entering the island. If that happens, the bird could disappear, “concludes Bengt Hansson, a professor at Lund University and one of the researchers behind the study.
Source: ABC Science