Hawai'i conservation alliance

2008 Runner Up Best Student Oral Presentation

Endemism and dispersal: comparative phylogeography of three surgeonfishes across the Hawaiian Archipelago

Jeff Eble, Robert Toonen, Brian Bowen
Hawaii Institute of Marine Biology, Kaneohe, HI, United States

It remains controversial whether a general correlation exists between range size and dispersal ability, where range-restricted endemism is indicative of lower dispersal ability. To evaluate this hypothesis we surveyed mitochondrial cytochrome b sequence variation in three surgeonfish species with vastly different ranges: Ctenochaetus strigosus, Hawaiian endemic, N = 531; Zebrasaoma flavescens, North Pacific, N = 560; Acanthurus nigrofuscus, Indo-
Pacific, N = 298. Collections were made throughout the 2500 km expanse of the Hawaiian Archipelago and adjacent Johnston Atoll. Analyses of molecular variance demonstrate that each species is capable of maintaining population connectivity on a scale of thousands of kilometers. However, collections of the endemic C. strigosus revealed significant restrictions to gene flow within the Papahānaumokuākea Marine National Monument. These results are
consistent with current surveys of Hawaiian reef fauna where widely distributed species exhibited genetic homogeneity across the archipelago while endemics revealed significant population subdivision over the same range. These findings invoke the tantalizing hypothesis that Hawaii’s endemic marine fauna evolved from species with reduced dispersal ability that, after initial colonization, could not maintain contact with parent populations.