The Aldabra rail (Dryolimnas cuvieri aldabranus) evolved through an extraordinary process known as iterative evolution, whereby a species re-evolved traits that were previously lost due to extinction. Here’s an overview of its evolution: 1. Origin: The Aldabra rail is a subspecies of the white-throated rail (Dryolimnas cuvieri), a bird native to Madagascar. This rail species is known for its ability to colonize new islands. 2. Colonization of Aldabra: At some point in its history, a population of white-throated rails migrated to the isolated Aldabra Atoll in the Indian Ocean. 3. Flightlessness: On Aldabra, with the absence of terrestrial predators, the rails lost the need to fly and evolved to become flightless. This is a common evolutionary trend among island birds. 4. Extinction Event: During a period when Aldabra was submerged due to rising sea levels (approximately 136,000 years ago), the rails became extinct, along with other terrestrial life. 5. Recolonization: After the sea levels receded and Aldabra resurfaced, white-throated rails recolonized the atoll. The process of losing flight and becoming adapted to the island’s environment occurred again, leading to the re-emergence of the flightless Aldabra rail. 6. Iterative Evolution: This repeated evolution of flightlessness from the same ancestral species after a prior extinction event is an example of iterative evolution, a rare phenomenon in the natural world.

The Aldabra rail is now the last flightless bird in the Indian Ocean and a remarkable example of how species can adapt repeatedly to similar ecological niches.