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Tags Current Affairs

Extinct bird re-appears after evolving

Date: 22 May 2020 Tags: Biodiversity

Issue

A once-extinct bird species "re-evolved" itself into existence and returned to the island it once colonized thousands of years ago.

 

Background

The parent species of the rail, indigenous to Madagascar, would frequently see its population explode, forcing the birds to migrate in great numbers from the island off the coast of East Africa.

 

Details

  • The Aldabra rail, named after the Aldabra Atoll it inhabits in the Seychelles, is the last surviving native flightless bird in the Indian Ocean region.

  • It is a descendant of the flying white-throated rail that is believed to have lost its ability to fly because the lack of predators made it unnecessary.

  • Fossils of the Aldabra rail have been discovered dating back 136,000 years, but the island has since been submerged by the ocean, wiping out almost all life.

  • The research revealed that the white-throated rail re-colonized the islands. But researchers believe that after the sea levels dropped and the bird reappeared, it became flightless once again.

  • Newer fossils showed the Aldabra rail was heavier than its ancestor, indicating that the bird had lost its ability to fly for a second time.

  • Once the bird became extinct after the flood, it took only 20,000 years for the white-throated rail to return and evolve into the flightless Aldabra rail bird again.

  • The extremely rare process is known as iterative evolution, the repeated evolution of a species from the same ancestor at different times in history.

  • This is one of the fastest recorded timelines of a bird losing its ability to fly, and the first and only known time that a species of bird has become flightless twice.

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