Mitochondrial and anonymous nuclear sequences and ten microsatellite loci were used to identify patterns of historical genetic structure and population expansion, reconstruct dated genealogies and assess levels of recent gene flow. These markers revealed strong concordant geographic structure within H. curtus with a prominent genetic break between populations broadly distributed in the Indian Ocean and the West Pacific. These populations were estimated to have diverged in the late Pliocene or early Pleistocene, and microsatellite admixture analyses suggested limited recent gene flow between them despite the current lack of barriers to dispersal, indicating possible cryptic species.
Subsequent divergence in the mid–late Pleistocene was detected within the West Pacific clade among the populations in the Phuket-Thailand region, South-East Asia and Australia, and two of these populations also showed genetic signals of recent range expansions. The results show that climatic fluctuations during the Plio-Pleistocene generated high levels of cryptic genetic diversity in H. curtus, and add to similar findings for diverse other marine groups in the archipelago.
, , , & (in press, ). . — ,