Image: COURTESY OF THE OXFORD UNIVERSITY MUSEUM OF NATURAL HISTORY |
Despite the dodo's status as the poster bird for extinction, its evolutionary history has long eluded scientists. Stranded on the Indian Ocean island of Mauritius (one of the Mascarene Islands), the flightless bird went extinct in 1681. Now new DNA analyses shed light on the genetic origins of the dodo and may help explain its island isolation. A report detailing the findings appears in the current issue of the journal Science.
Beth Shapiro of the University of Oxford and colleagues extracted DNA from the only surviving dodo specimen that contains soft tissues: the so-called Alice in Wonderland Dodo, which is housed at the Oxford University Museum of Natural History and thought to have inspired a character created by author Lewis Carroll. The researchers compared the dodo DNA to that of its closest cousin--the extinct flightless solitaire--and 35 surviving species of pigeons and doves. They determined that both the dodo and the solitaire belong to the pigeon family, also known as the Columbiformes. The birds' closest living relative, the team reports, is the Nicobar pigeon, which lives in Southeast Asia. Other close cousins include the crowned pigeons of New Guinea and the peculiar tooth-billed pigeon of Samoa.
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According to study co-author Alan Cooper of the Henry Wellcome Ancient Biomolecules Center, the findings suggest that the dodo and the solitaire separated from their South Asian relatives about 40 million years ago and later flew across the Indian Ocean to the Mascarene Islands. The birds then diverged from each other around 26 million years ago. But because Mauritius didn't emerge until eight million years ago and Rodrigues Island (home to the solitaire) until 1.5 million years ago, the scientists suggest that the birds used other islands in the Mascarene Island chain as stepping stones. It remains unclear whether this migration was aided by flight or not. "The isolation of Rodrigues Island," Cooper notes, "suggests that the solitaire, at least, may have still been able to fly as recently as 1.5 million years ago."