A bird from Madagascar flew to a remote island and evolved to become flightless only to be exterminated by rising seas. But, according to a new study, the same species recolonized the island after sea levels fell and again lost the ability to fly, LiveScience reports. Between 136,000 and 240,000 years ago, white-throated rails from Madagascar colonized an island in the Aldabra atoll. The island’s accessible food and lack of predators eliminated the birds’ need for flight, eventually causing them to go the way of the ostrich and become flightless. But 136,000 years ago, the birds’ gravy train was interrupted by a catastrophic flood that inundated the island and wiped the birds out. A new analysis of fossils found on the island shows that after the island dried out, another wayward flock of white-throated rails arrived, and again evolved to become flightless, the study authors report in the Zoological Journal of the Linnean Society. The study provides one of the clearest examples of a rare phenomenon called iterative evolution, in which nearly identical species evolve from the same ancestor at different times.
*Correction, 17 May, 11:45 a.m.: This article has been updated to reflect the fact that the repeated evolution of flightlessness by the white-throated rail on the Aldabra atoll produced two subspecies thousands of years apart, and not a single subspecies that disappeared and reappeared.