Marine Suture Zones As Evidence of Postglacial Recolonization in an Indo-Pacific Aquarium Fish

The Coral Triangle has long been recognized as the marine biodiversity center of the world. Intra-specific population structuring of marine organisms in the area has been linked with patterns in ocean currents, larval activity and recruitment, and isolation of ocean basins during periods of low sea level. In this study, we investigate the population structure of the three-spot dascyllus (Dascyllus trimaculatus), a popular aquarium export from coral reefs of the Indo-Pacific, using the mitochondrial d-loop and microsatellites. Analysis revealed a biogeographic break between the Indian and Pacific Oceans, as exhibited in many other taxa, and showed evidence of recolonization of previously isolated shelf regions and basins, resulting in “suture zones” where multiple ancient clades meet. We see evidence for such zones over the Sunda Shelf, the boundary between the Philippines and Indonesia, and along a vertical divide through the Philippine archipelago. We suspect that postglacial recolonization remains a driving force in the structuring of mobile marine species. Population studies such as this one are often used to design marine protected areas by identifying regions of homogeneity in species.