The depauperate marine ecosystems of the Hawaiian Archipelago share a high proportion of species with the southern and western Pacific, indicating historical and/or ongoing connections across the large oceanic expanse separating Hawaii from its nearest neighbors. The rate and direction of these interactions are, however, unknown. While previous biogeographic studies have consistently described Hawaii as a diversity sink, prevailing currents likely offer opportunities for larval export. To assess interactions between the remote reefs of the Hawaiian Archipelago and the species rich communities of the Central and West Pacific, we surveyed 14 nuclear microsatellite loci (nDNA; n = 857) and a 614 bp segment of mitochondrial cytochrome b (mtDNA; n = 654) in the Yellow Tang (Zebrasoma flavescens). Concordant frequency shifts in both nDNA and mtDNA reveal significant population differentiation among three West Pacific sites and Hawaii (nDNA F' _CT = 0.116, mtDNA ϕ _CT = 0.098, P < 0.001). SAMOVA analyses of microsatellite data additionally indicate fine scale differentiation within the 2600 km Hawaiian Archipelago (F' _SC = 0.026; P < 0.001), with implications for management of this heavily-exploited aquarium fish. Mismatch analyses indicate the oldest contemporary populations are in the Hawaiian Archipelago (circa 318,000 y), with younger populations in the West Pacific (91,000 - 175,000 y). Estimates of Yellow Tang historical demography contradict expectations of Hawaii as a population sink, and instead indicate asymmetrical gene flow, with Hawaii exporting rather than importing Yellow Tang larvae.

LV Basch

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