Molecular Phylogenetic Relationships of Cibotium and Origin of the Hawaiian Endemics

The tree fern genus Cibotium comprises nine species distributed in tropical regions of Asia, Mesoamerica, and the Hawaiian Islands. The four Hawaiian species are endemic to the Hawaiian Islands. The goals of this paper were to determine the relationships among the Cibotium species, determine whether the Hawaiian species are monophyletic, and infer the dispersal pathway likely responsible for delivering an ancestral Cibotium species to the Hawaiian Islands. Molecular phylogenetic analyses based on four coding and five non-coding plastid DNA sequences supported Hawaiian Cibotium as monophyletic, suggesting a single colonization of the Hawaiian Islands. Hawaiian Cibotium are most closely related to species in Mesoamerica. If the ancestor of Hawaiian Cibotium dispersed to the Hawaiian Islands via wind dispersed spores, our analyses suggest the trade winds or storms delivered spores from Mesoamerica or the Hawaiian Islands were colonized first by a species from Asia, followed by subsequent dispersal to Mesoamerica from Hawai'i. Our analyses do not allow us to favor one hypothesis over the other.