Phylogenetic relationships of the Eastern Polynesian swiftlets (Aerodramus, Apodidae) and considerations on other Western Pacific swiftlets

The patterns of colonisation and phylogenetic relationships of the swiftlets from Oceania, and in particular from the remotest archipelagos of Polynesia, remain a puzzle. In this study we used mitochondrial and nuclear DNA sequence data to infer the colonisation patterns of swiftlets endemic to Eastern Polynesia. The three endemic taxa did not form a monophyletic group. The Tahiti Swiftlet (Aerodramus leucophaeus) and the Marquesan Swiftlet (A. ocistus) were closely related to the group formed by the Himalayan Swiftlet (A. brevirostris) and the two Indian Ocean species, Seychelles Swiftlet (A. elaphrus) and Mascarene Swiftlet (A. francicus). The third taxon from Eastern Polynesia, the Atiu Swiftlet (A. sawtelli) from the Cook Islands, forms a group with the Mariana Swiftlet (A. bartschi), and the Uniform Swiftlet (A. vanikorensis), a widely distributed species, from the Philippines to Melanesia. Thus the colonisation of the remotest areas of Oceania by swiftlets occurred through long-distance events, as opposed to a regular, stepping-stone pattern from the west to the east. These results add to the body of evidence suggesting that Eastern Polynesia constituted a ‘sink’, from which birds did not come back to recolonise western islands.