New Research Progress in the Phylogeography of the Indo-Pacific Humpback Dolphin

Recently, the marine rare species conservation research group of Marine Biology and Ecology Laboratory of TIO published a paper “Early divergence and differential population histories of the Indo-Pacific humpback dolphin in the Pacific and Indian Oceans” in the《Integrative Zoology》, with collaboration of the Institute of Deep-sea Science and Engineering, CAS and Thailand Marine and Coastal Resources Research Center and Phuket Marine Biological Research Center, showing the new research progress in the phylogeography of the Indo-Pacific humpback dolphin (Sousa. chinensis).

The dataset collected in this study along with previously reported data well covers the entire range of this species, and is by far the most representative sample set ever reported for the Indo-Pacific humpback dolphin, including 7 populations from the northern South China Sea (including XMB; PRD; LZB, and BBG), Gulf of Thailand, the Indian Ocean side of Thailand, and the Bay of Bengal.

These data revealed that the ancestral Indo-Pacific humpback dolphin might have split during the transition from the Oligocene to Miocene (23.45 Mya, 95% HPD: 16.65 - 26.55 Mya), and then dispersed along the Pacific and Indian Ocean coasts of Asia. Genetic differentiation/distance between the humpback dolphins from the northern and southern South China Sea met the sub-species threshold value proposed for marine mammals, whereas that between the humpback dolphins in the Pacific and the Indian Ocean was above the species threshold. Genetic differentiation was also detected in some pairwise populations in the northern South China Sea (XMB-BBG,LZB-BBG,PRD-LZB). The results reveal that the current taxonomic classification of Indo-Pacific humpback dolphins may not reflect their phylogeography. The genetic divergence between the currently recognized conspecific populations between east and west sides of the Indo-China Peninsula is profoundly higher than the species-level divergence reported for the marine mammals. We also suggest that the current taxonomy of S. chinensis should be re-examined using genome-wide SNP data, which provides more phylogenetic information compared with a single genetic marker.

Link to paper:

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