Clockwise from left: Bidens orofenensis, Tahiti; Mt Orohena, Tahiti; Hawaii; and the Solomon Islands.
The Compositae (Asteraceae) family is the largest flowering plant family with ca. 25,000 species. Its members have successfully colonized the Pacific Islands 38-43 times (Indigenous clades) resulting in 36 genera (six with more than one introduction) and 164 species.
Phylogenies have been generated for all but two of the species and so it is now possible to examine the patterns of evolution in the Pacific. Dominating the family phylogenies are a few clades that have successfully colonized three archipelagos: Hawaii, Marquesas and the Society Islands.
Of the large radiations two had remained unstudied on a global scale: Bidens (41 Pacific species) and Melanthera (23). Phylogenies for these two genera have been produced, including a large selections of outgroups, and we now have a better understanding of their radiation in the Pacific.
When these data are combined with existing phylogenies for the remainder of the Pacific Compositae several conclusions can be made including these: the most likely means of colonization is long distance dispersal from the closest source area and the clades that are successful can be predicted based on the overall phylogeny of the family. There are a few novel events of interest, all in the Hawaiian Islands.