Phylogeographic patterns of island radiation in extinct parrots of the Indian Ocean

Principal Investigator: Dr. Jim Groombridgeparrot
Funding: The Systematics Research Fund Grant
Collaborators: Natural History Museum

The Indian Ocean islands were once a hotspot of parrot endemism, but avian extinctions since 1600, typified most famously by extinction of the Dodo, have eroded any evidence of the evolutionary history of this regions’ avifauna. Historically, endemic forms of Psittacula parakeet existed on the islands of Reunion (P. eques), Seychelles (P. wardi), Rodrigues (P. exsul), and Mauritius (P. echo), but nearly all were extinct by 1860, and today the region’s only endemic island parakeet survives on Mauritius. The Mauritius parakeet was successfully recovered from a few individuals to over 250 birds today, and is ecologically a very distinct island form, sharing few of the distinctive morphological and plumage traits with continental Psittacula.

A molecular phylogeny of extant Psittacula parakeets derived from mitochondrial DNA sequence (Groombridge et al. 2004) provides an ideal framework for this project, to address the evolutionary history of these extinct island forms, by sequencing DNA from museum skins to establish the route of radiation across the Indian ocean and the distinctiveness of the endangered Mauritius parakeet. The existing molecular phylogeny identifies three major clades within Psittacula that are consistent with observed similarities of head and body plumage pattern, and with some elements of geographic distribution. However, the Mauritius parakeet groups in between the African and Indian ringneck parakeet (P. k. krameri and P. k. manillensis), such that the chronology of colonisation events from island-to-island, and the evolutionary distinctiveness of the Mauritius parakeet remains unresolved until the extinct taxa can be incorporated.

The most parsimonious route southwards from central Asia would involve either direct colonisation of the Mascarene Islands from India, or a longer stepping-stone route via the Seychelles. Alternatively, the Seychelles might have been colonised last, a chronology that may explain fossil evidence for other extinct parrot genera. This project is extracting DNA sequence from museum specimens of the extinct species and incorporating them on to the existing molecular phylogeny. This work is supported by a research grant from The Systematics Research Fund, in association with The Systematics Association and The Linnean Society of London. Partners on this project include the Natural History Museum, partners in Cambridge, and additional museums in the UK.

This molecular work is being carried out by Visiting Researcher, Dr. Samit Kundu

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