An island half the size of Manhattan in the South Atlantic is so isolated that the & inaccessible island & # 39; is called. On that island, and only on that island, there are nearly 6,000 lean feather balls called Inaccessible Island rails. But they can not fly and the island is only a few million years old. How did the birds get there?
A new analysis may have solved the mystery. The DNA of the bird shows that it has evolved relatively recently by a visitor to the island, and lost its ability to fly from the forces of natural selection.
"It is quite spectacular that the smallest living flying birds have ended up in one of the most remote places ever," said study author Martin Stervander, postdoctoral researcher at the University of Oregon, at Gizmodo. "It seems that the birds arrived on the island and because they were not at all dangerous with predators, there was not much reason to fly."
When scientists first described the bird in the 1920s, they knew immediately that they were looking at something strange. Inaccessible island is 3500 km from South America and 2800 km from southern Africa. The bird does not occupy any of the two nearby islands less than 32 km away.
They suggested that, before the theory of plate tectonics existed, the bird would somehow walk to the island over a sort of sunken land bridge. They placed it in his own genus, Atlantisia. More recent research has suggested that the bird comes from rails in Africa.
The scientists behind the new paper have other analysis tools than bird forms and geography at their disposal. In September 2011 they conquered a male inaccessible island rail, sampled the blood, sequenced the DNA and compared the results with data on other rails.
They concluded that the ancestor of the track was a South American bird that arrived on the island about 1.5 million years ago, and that it is more likely that a member of the laterallus sex, including contemporary birds such as the dot-winged crake, the Galapagos crake and the similar-looking black rail, according to the article published in the journal Molecular Phylogenetics and Evolution.
It is logical. Rails are notorious for flying wherever they are, with 53 existing or recently extinct species that occur only on islands, and 32 species thereby lose some or all of their flying ability. Probably a population of the inaccessible island traveler's flew east into the Atlantic and landed on the island – a sweet enough performance that they no longer had to fly.
"When the train arrived at Inaccessible Island, they had all their food to roam around and there was nothing to escape, there is not much need for flying," said Stervander. The only threats of the bird on Inaccessible Island are another bird species that sometimes eats eggs, and perhaps a few seabirds.
It is unclear why the railway did not go to the other two islands – perhaps a population has tried and failed.
Stervander pointed out that more research should be done. The dataset on track was incomplete, so perhaps more data will reveal that the bird really belongs to a different gender.
And although the bird lives the good life, it is still considered a vulnerable species. Fly-free bird populations can easily collapse when people bring invasive species, such as cats or rats.
This article might solve the cutest mystery in the South Atlantic. But if you are planning to visit the island (which is no sinecure), make sure you do nothing to harm the birds.[Molecular Phylogenetics and Evolution]