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Research published this month in Science by a team
from Oxford and the Natural History Museum, London, has
shed new light on the genetic origins of the Dodo as well
as offering solutions as to how the species came to be isolated
on the island of Mauritius.
Despite being the emblem of extinction, the evolutionary
history of the Dodo is poorly understood. The extreme evolutionary
changes it has undergone (e.g. gigantism, flightlessness)
on the island of Mauritius have even concealed its closest
relatives within the birds-and it has been linked with everything
from parrots, pigeons, and shorebirds, to birds of prey.
Dr Alan Cooper and Dr Beth Shapiro from Oxford's Henry
Wellcome Ancient Biomolecules Centre, Dr Dean Sibthorpe,
Andrew Rambaut, Dr Graham Wragg, Dr Olaf Bininda-Emonds
and Dr Patricia Lee from the Department of Zoology, and
Dr Jeremy Austin from the Natural History Museum, London,
carried out the research after gaining permission from the
University Museum of Natural History to examine their valuable
Dodo specimen. Tiny fragments of Dodo DNA were retrieved
from bone and tissue samples from the 300-year-old 'Alice
in Wonderland' specimen-so called because it was the inspiration
for the character in the Lewis Carroll book. This specimen
is the best preserved Dodo in the world, and the only one
still with soft tissues.
The Dodo genetic sequences were compared to 1,400 base
pairs of DNA from the Solitaire, an extinct Dodo-like bird
from neighbouring Rodrigues Island, and 35 species of pigeon
and doves, as well as other bird groups. The DNA showed
that the closest living relative to the Dodo and Solitaire
was the Nicobar pigeon, from southeast Asia-and that the
next nearest relatives were the crowned pigeons of New Guinea,
and the unusual tooth-billed pigeon of Samoa.
Dr Alan Cooper, Director of the Henry Wellcome Ancient
Biomolecules Centre, described how the DNA revealed the
evolutionary history of this previously unrecognised group,
saying: 'The genetic differences suggest that the ancestor
of the Dodo and Solitaire separated from their Southeast
Asian relatives around 40 million years ago, and sometime
after this point flew across the Indian Ocean to the Mascarene
Islands. The data then indicate the Dodo and Solitaire speciated
from each other around 26 million years ago, about the same
time that geologists think the first land appeared on the
Mascarene plateau. However, Mauritius and Rodrigues islands
are much younger (8 and 1.5 million years respectively),
implying that the Dodo and Solitaire used now sunken islands
as stepping-stones. Furthermore, the presence of the Solitaire
on the geographically isolated Rodrigues Island suggests
that it, at least, may have still been able to fly as recently
as 1.5 million years ago.
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