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Phylogeny and biogeography of the sandalwoods ( Santalum , Santalaceae): repeated dispersals throughout the Pacific
Author(s) -
Harbaugh Danica T.,
Baldwin Bruce G.
Publication year - 2007
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.94.6.1028
Subject(s) - biology , biological dispersal , monophyly , biogeography , phylogenetic tree , ecology , santalum album , insular biogeography , phylogeography , maximum parsimony , phylogenetics , clade , population , biochemistry , demography , sociology , gene
Results of the first genus‐wide phylogenetic analysis for Santalum (Santalaceae), using a combination of 18S–26S nuclear ribosomal (ITS, ETS) and chloroplast (3′ trnK 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 Santalum 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 Santalum 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 Polynesica , Santalum , and Solenantha , the widespread Australian species S. lanceolatum , and the Hawaiian species S. freycinetianum are not monophyletic and need taxonomic revision, which is currently being pursued.