Genetic population structure of the convict surgeonfish Acanthurus triostegus: a phylogeographic reassessment across...

This study investigates the genetic population structure and connectivity of Acanthurus triostegus in five Indo-Pacific biogeographic regions (western and eastern Indian Ocean, western, central and eastern Pacific Ocean), using a mitochondrial DNA marker spanning the ATPase8 and ATPase6 gene regions. In order to assess the phylogeography and genetic population structure of A. triostegus across its range, 35 individuals were sampled from five localities in the western Indian Ocean and complemented with 227 sequences from two previous studies. Results from the overall analysis of molecular variance (AMOVA) without a priori grouping showed evidence of significant differentiation in the Indo-Pacific, with 25 (8.3%) out of 300 pairwise Φ_ST comparisons being significant. However, the hierarchical AMOVA grouping of Indian and Pacific Ocean populations failed to support the vicariance hypothesis, showing a lack of a genetic break between the two ocean basins. Instead, the correlation between pairwise Φ_ST values and geographic distance showed that dispersal of A. triostegus in the Indo-Pacific Ocean follows an isolation-by-distance model. Three haplogroups could be deduced from the haplotype network and phylogenetic tree, with haplogroup 1 and 2 dominating the Indian and the Pacific Ocean, respectively, while haplogroup 3 exclusively occurring in the Hawaiian Archipelago of the central Pacific Ocean.