Phylogeny and biogeography of the sandalwoods (<i>Santalum</i>, Santalaceae): repeated dispersals throughout the Pacific

<jats:p>Results of the first genus‐wide phylogenetic analysis for <jats:italic>Santalum</jats:italic> (Santalaceae), using a combination of 18S–26S nuclear ribosomal (ITS, ETS) and chloroplast (3′ <jats:italic>trnK</jats:italic> intron) DNA sequences, provide new perspectives on relationships and biogeographic patterns among the widespread and economically important sandalwoods. Congruent trees based on maximum parsimony, maximum likelihood, and Bayesian methods support an origin of <jats:italic>Santalum</jats:italic> in Australia and at least five putatively bird‐mediated, long‐distance dispersal events out of Australia, with two colonizations of Melanesia, two of the Hawaiian Islands, and one of the Juan Fernandez Islands. The phylogenetic data also provide the best available evidence for plant dispersal out of the Hawaiian Islands to the Bonin Islands and eastern Polynesia. Inability to reject rate constancy of <jats:italic>Santalum</jats:italic> ITS evolution and use of fossil‐based calibrations yielded estimates for timing of speciation and colonization events in the Pacific, with dates of 1.0–1.5 million yr ago (Ma) and 0.4–0.6 Ma for onset of diversification of the two Hawaiian lineages. The results indicate that the previously recognized sections <jats:italic>Polynesica</jats:italic>, <jats:italic>Santalum</jats:italic>, and <jats:italic>Solenantha</jats:italic>, the widespread Australian species <jats:italic>S. lanceolatum</jats:italic>, and the Hawaiian species <jats:italic>S. freycinetianum</jats:italic> are not monophyletic and need taxonomic revision, which is currently being pursued.</jats:p>