The Application of Genomics for the Conservation of Herbivorous Reef Fishes

Coral reefs within the Coral Triangle are home to the greatest marine diversity on the globe, but are often subjected to extreme fishing pressure.  Marine protected areas (MPAs) have been proven to be effective management tools in this region, however the ability of MPAs to promote connectivity and resilience across large distances is still poorly understood.  We used RADseq to discover 4,235 and 12,619 SNPs for two species of parrotfish (Scarus niger and Chlorurus bleekeri) and 16,853 SNPs a rabbitfish (Siganus guttatus) collected in the Philippines and Vietnam.  Population analyses suggested high levels of gene flow within the Philippines ( pairwise F_ST ranging from 0.0007 to 0.0018), week structure between Vietnam and the Philippines (pairwise F_ST between 0.021 and 0.025), and estimates of effective population size were relatively large (1,200 – 2,000).  Additionally, a sibling analysis revealed one pair of putative full siblings (r = 0.773) and one pair of putative half siblings (r = 0.191) between sites separated by more than 400km.  The low F_st values and sibling pairs across distant reefs indicate both genetic and demographic connectivity.  These patterns suggest that MPAs within the Philippines could theoretically provide an influx of larvae to overfished reefs throughout the region.