The mysterious spotted green pigeon (Caloenas maculata) was related to the dodo, according to research led by Griffith University scientists and based on DNA from the only known specimen of the pigeon in the world.
A paper published in the open access journal BMC Evolutionary Biology supports the theory that the spotted green pigeon and the dodo were descended from ‘island hopping’ ancestors.
A research team comprising Dr Tim Heupink, from Griffith’s Environmental Futures Research Institute, Dean of Research (Griffith Sciences) Professor David Lambert, and Mr Hein van Grouw, of the UK’s Natural History Museum, established the genetic make-up of Caloenas maculata after analysing fragments of DNA taken from tiny pieces of feather.
The samples were sourced from the world’s only known example of the spotted green pigeon, better known as the ‘Liverpool pigeon’, which is held in the World Museum in Liverpool in the UK. The only other known specimen has since been lost and there are no records of the bird in the wild.
Furthermore, there is no record of where the pigeon was found and until this latest research it wasn’t known whether the spotted green pigeon was an actual species or merely an unusual form of the Nicobar pigeon found in areas around Indonesia.
Dr Heupink says that although the pigeon DNA was highly fragmented due to age, by focusing on three ‘mini barcodes’ – sections of DNA unique to most bird species – and completing analysis and comparisons with other species, the spotted green pigeon can be confirmed as a separate species with a unique DNA barcode.
Genetically most closely related to the Nicobar pigeon, Caloenas maculata can also be linked to the dodo and Rodrigues solitaire, both extinct birds from islands near Madagascar.
Dr Heupink says the spotted green pigeon shows signs of a semi-terrestrial island lifestyle and the ability to fly. The Nicobar pigeon shows similar habits and has a preference for travelling between small islands.
The scientists contend that this lifestyle, together with the relationship of both pigeons to the dodo and Rodrigues solitaire, supports an evolutionary theory that the ancestors of these birds were ‘island hoppers’, moving between islands around India and southeast Asia.
The birds that settled on particular islands then evolved into individual species. The dodo’s ancestor managed to hop as far as the island of Mauritius, near Madagascar, where it then lost the ability to fly.
The last recorded sighting of a dodo dates to the mid-17th century. The spotted green pigeon was first described more than 100 years later, in 1783.
“This study improves our ability to identify novel species from historic remains and also those that are not novel after all,” says Dr Heupink.
“Ultimately this will help us to measure and understand the extinction of local populations and entire species.”
Professor Lambert says the research is not only significant for its identification of the spotted green pigeon as a distinct species, but it also enhances appreciation of museums as repositories of material enabling new scientific research and discoveries.
“DNA technology is getting better and better and this means scientists can draw samples from very old material,” he says. “Museums are the guardians of much of this material and are rightly cautious about allowing scientists to undertake what is known as destructive sampling, even if the samples taken are very small.
“In the case of the spotted green pigeon, because there is only one specimen in the world I believe the World Museum should be congratulated for granting access to it.”
To read the paper, go to Spotted Green Pigeon