Biogeographical Origins of Hawaiian Diplopterygium pinnatum by Long Distance Wind Dispersal

This study was designed to investigate a possible biogeographical origin and mechanism of dispersal ofthe Hawaiian fern Diplopterygium pinnatum. Molecular phylogenetic analyses were conducted on trnL-F and rbcL, cpDNA regions, for seven species of the genus Diplopterygium and three outgroups. Maximum parsimony and maximum likelihood analyses were used for phylogenetic reconstruction. Three hypotheses were tested: that the ancestor ofD. pinnatum originated from 1) an IndoPacific source and traveled to Hawaii via the jet stream, 2) an American source and traveled to Hawaii via the trade winds, or 3) an Austral source and traveled to Hawaii by a combination of an intertropical convergence zone (ITCZ) shift, Hadley cell air movement, and the trade winds. The two methods ofreconstruction, maximum parsimony and maximum likelihood, produced similar trees with similar support. The second hypothesis was rejected and the first and third hypotheses cannot be distinguished.