Genetic Structure of Culcita sp. Pincushion Seastar in The Coral Triangle

From the Coral Triangle, which is the global centre of marine biodiversity, species richness tends to decrease eastward across the Pacific Ocean and westward across the Indian Ocean. However, this region is severely threatened by both human and natural disturbances, calling for urgent conservation efforts. Conservation and management decisions inevitably require definition of the limits of population structure of each species as well as mechanisms that produce high biodiversity in the Coral Triangle. In this study we sequenced the mitochondrial COI region of the pincushion seastar, Culcita sp., a common coral reef seastar whose life history resembles other well-studied coral reef seastars. We found a large genetic difference between Indian (Culcita schmideliana) and Pacific Ocean (Culcita novaeguineae) lineages. All the populations (except from Thailand) had Pacific mtDNA haplotypes, while central and western Indonesian populations had both Indian and Pacific haplotypes, showing a sign of sympatric distribution of these two genetic lineages around these areas. Overall gene flow of Culcita sp. in the Coral Triangle was strong and resembled that of Acanthaster planci with similar life history traits. Further analysis using nuclear marker might reveal possible hybridization between the distinct genetic lineages of the species in this region. Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012.