Diversification of the tropical Pacific avifauna

Abstract

I investigated the origins and diversification of Pacific avifaunas. Chapters 1, 2, and 4 elucidate the evolutionary history of three classically polytypic species complexes of Pacific island birds using multilocus phylogeographic approaches. The focal taxa were: Ceyx lepidus (Aves: Alcedinidae), Pachycephala pectoralis (Aves: Pachycephalidae), and Todiramphus chloris (Aves: Alcedinidae). In chapter 3, I examined the systematic relationships of 14 species of Pacific honeyeaters (Aves: Meliphagidae) relative to continental lineages. Each of these studies revealed novel biogeographical patterns heretofore underappreciated in Pacific birds. All three species complexes underwent rapid diversification with extensive genetic and phenotypic differentiation across widespread island archipelagos spanning thousands of kilometers from southeast Asia to Polynesia. This pattern was evidenced by phylogenies with short basal internodes, long stem lineages, and shallow divergences within each taxon. Todiramphus was noteworthy because it has attained extensive reproductive isolation, despite the recency of the radiation, as evidenced by multiple sympatric taxa throughout the Pacific. The work on meliphagid honeyeaters found extensive paraphyly of Pacific lineages with respect to their presumed continental congeners. I found evidence for a Central Polynesian radiation that included taxa from the eastern Solomon Islands, Fiji, Samoa, and Tonga. Throughout this dissertation I draw inferences on the processes of origination, diversification, and extinction in Pacific avifaunas using a comparative framework across multiple lineages at different scales of differentiation.