Phylogenetic relationships of the Eastern Polynesian swiftlets (<i>Aerodramus</i>, 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 (<i>Aerodramus leucophaeus</i>) and the Marquesan Swiftlet (<i>A. ocistus</i>) were closely related to the group formed by the Himalayan Swiftlet (<i>A. brevirostris</i>) and the two Indian Ocean species, Seychelles Swiftlet (<i>A. elaphrus</i>) and Mascarene Swiftlet (<i>A. francicus</i>). The third taxon from Eastern Polynesia, the Atiu Swiftlet (<i>A. sawtelli</i>) from the Cook Islands, forms a group with the Mariana Swiftlet (<i>A. bartschi</i>), and the Uniform Swiftlet (<i>A. vanikorensis</i>), 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.