P89M6G White-throated Rail (Dryolimnas cuvieri), endemic to Madagascar and the last flightless species of bird in the Indian Ocean.
P89M6G White-throated Rail (Dryolimnas cuvieri), endemic to Madagascar and the last flightless species of bird in the Indian Ocean.

Bird evolves back from extinction

An extinct bird has risen from the dead thanks to a rare evolutionary process, according to new research.

The white-throated rail bird can be found in Madagascar and fossils suggest it lived there tens of thousand of years ago, died out and then evolved again.

Researchers from the University of Portsmouth and London's Natural History Museum discovered that a species of rail bird successfully colonised a small island called Aldabra and became flightless, then died out and then the whole process happened again.

They think this happened due to 'iterative evolution', which refers to the repeated evolution of similar body parts due to genetics from the same ancestor but at different times.

White-throated Rail (Dryolimnas cuvieri), endemic to Madagascar and the last flightless species of bird in the Indian Ocean.
White-throated Rail (Dryolimnas cuvieri), endemic to Madagascar and the last flightless species of bird in the Indian Ocean.

In order to determine this, the researchers studied fossil evidence from up to 100,000 years ago and found a species of bird that was structurally very similar to the white-throated rail bird but it died out around 20,000 years ago.

The resurrected bird is the last flightless bird that can be found in the Indian Ocean region today and it initially died out due to rising sea levels because it had lost the ability to fly to higher ground.

Fossils proves that birds similar to them existed thousands of years ago.
Fossils proves that birds similar to them existed thousands of years ago.

Lead researcher Dr Julian Hume, avian palaeontologist and Research Associate at the Natural History Museum, said: "These unique fossils provide irrefutable evidence that a member of the rail family colonised the [island], most likely from Madagascar, and became flightless independently on each occasion.

"Fossil evidence presented here is unique for rails, and epitomises the ability of these birds to successfully colonise isolated islands and evolve flightlessness on multiple occasions."

Aldabra is a ring shaped coral island, referred to as an atoll, near the coast of Madagascar.
Aldabra is a ring shaped coral island, referred to as an atoll, near the coast of Madagascar.

Co-author Professor David Martill, from the University of Portsmouth, said: "We know of no other example in rails, or of birds in general, that demonstrates this phenomenon so evidently.

"Only on Aldabra, which has the oldest palaeontological record of any oceanic island within the Indian Ocean region, is fossil evidence available that demonstrates the effects of changing sea levels on extinction and recolonisation events.

"Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion."

Flying ancestors of the present day white-throated rail re-colonised Aldabra but, because the descendants have evolved to not be able to fly again, rising sea levels could put them in danger once more.

The study has been published in the latest issue of the Zoological Journal of the Linnean Society.

 

This article originally appeared on The Sun and was reproduced with permission.

 

These wing bones taken from rail bird fossils show how the size of the bird changed over time from when it had wings that could fly (right) to when it could not (left). Picture: University of Portsmouth/NHM
These wing bones taken from rail bird fossils show how the size of the bird changed over time from when it had wings that could fly (right) to when it could not (left). Picture: University of Portsmouth/NHM

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