The white-throated rail is the only flightless bird known in the Indian Ocean area. New research has found that it had once gone extinct, but rose from the dead thanks to a rare process called “iterative evolution”. It means the repeated evolution of similar or parallel structures from the same ancestor but at different times.
The study, from the University of Portsmouth and the UK’s Natural History Museum, is published in the Zoological Journal of the Linnean Society. It found that on two occasions, separated by tens of thousands of years, a rail species was able to colonise an island called Aldabra and subsequently became flightless on both occasions. The last surviving colony is still found on the island.
The white-throated rail is a chicken-sized bird, indigenous to Madagascar. Migrating to Aldabra, the rails evolved so that they lost the ability to fly. However, Aldabra disappeared under the the sea during an inundation event around 136,000 years ago. The researchers studied fossil evidence from 100,000 years ago when the island was recolonised by flightless rails, and compared with fossils from before the inundation event. They concluded that one species from Madagascar gave rise to two different species of flightless rail on Aldabra in the space of a few thousand years. —Source: University of Portsmouth