Microevolutionary patterns and processes of the native Hawaiian colonizingfern Odontosoria chinensis (lindsaeaceae)

The vascular-plant flora of the Hawaiian Islands is characterized by one of the highest rates of species endemism in the world. Among flowering plants , approximately 89% of species are endemic, and among pteridophytes, about 76% are endemic. At the single-island level, however, rates of species ende mism vary dramatically between these two groups with 80% of angiosperms and only 6% of pteridophytes being single-island endemics. Thus, in many group s of Hawaiian angiosperms, it is possible to link studies of phylogeny, evo lution, and biogeographic history at the interspecific and interisland leve ls. In contrast, the low level of single-island species endemism among Hawa iian pteridophytes makes similar interspecific and interisland studies near ly impossible. Higher levels of interisland gene flow may account for the d ifferent levels of single-island endemism in Hawaiian pteridophytes relativ e to angiosperms. The primary question we addressed in the present study wa s: Can we infer microevolutionary patterns and processes among populations within widespread species of Hawaiian pteridophytes wherein gene flow is pr obably common? To address this broad question, we conducted a population ge netic study of the native Hawaiian colonizing species Odontosoria chinensis . Data from allozyme analyses allowed us to infer: (1) significant genetic differentiation among populations from different islands; (2) historical pa tterns of dispersal between particular pairs of islands; (3) archipelago-le vel patterns of dispersal and colonization; (4) founder effects among popul ations on the youngest island of Hawaii; and, (5) that this species primari ly reproduces via outcrossing, but may possess a mixed-mating system.