Regional population structure of Montipora capitata across the Hawaiian Archipelago

Montipora capitata Dana, 1846 is one of the most successful reef-building corals in the Hawaiian Archipelago, both in terms of geographic distribution and relative abundance. Here, we examine population genetic structure using eight microsatellite loci to make inferences about exchange among geographical regions throughout Hawaiian waters to inform management and conservation efforts. We collected biopsy samples (n = 560) from colonies at each of 11 islands/atolls along the archipelago in addition to Johnston Atoll, about 1328 km to the southwest. We found very few potential clones (<2%) in our sampling (551 of 560 colonies had unique multi-locus genotypes), indicating that reproduction is predominantly sexual. Likewise, significant genetic structuring among most locations (pairwise F′ _ST = 0.05 to 0.49, only two <0.10;P < 0.01) indicates that gene flow between islands is highly limited. Overall, we found four main regional genetic groupings of M. capitata within state waters, one comprised of the Main Hawaiian Islands, one off the three northwestern-most Hawaiian Islands, and two groupings encompassing the middle of the northwestern chain and Johnston Atoll. Despite the potential for extended pelagic larval development periods (>200 d), estimates of contemporary dispersal were uniformly low, with most sites being estimated at >90% self-recruitment. These data imply that the majority of M. capitata colonies found at a given island/atoll across the Hawaiian Archipelago are derived from self-recruitment, and argue for more local-scale management of coral reef resources than has been considered to date.