Marine and Freshwater Research
Phylogenetic, dolphin, taxonomy, humpback dolphins, dolphins, distribution, Atlantic, mitochondrial DNA, DNA, control region, populations, population, South Africa, China, Australia, Sousa teuszii, Atlantic humpback dolphin
Humpback dolphins (Sousa spp.) have a wide distribution in the tropical Atlantic and Indo-Pacific Oceans and a confused taxonomy. Morphological assessments suggest three species groupings – Sousa teuszii (eastern Atlantic), Sousa plumbea (western Indo-Pacific), and Sousa chinensis (eastern Indo-Pacific) – but most taxonomies recognise only two species – S. chinensis (Indo-Pacific), and S. teuszii (Atlantic). To investigate phylogenetic relationships, mitochondrial DNA control region sequences (338 base pairs) from 72 Sousa representing three populations in the Indo-Pacific (South Africa: S. plumbea, n=23; China: S. chinensis, n=19; and Australia: S. chinensis, n=28), and S. teuszii in the Atlantic (Mauritania, n=2) were generated. All three Indo-Pacific populations formed robust, monophyletic clades with high bootstrap (BS) and Bayesian posterior probability (BPP) scores. Surprisingly, humpback dolphins from South Africa and China formed a strongly-supported clade with the Atlantic S. teuszii (BS 63%, BPP 0.92) to the exclusion of animals from Australia. Genetic divergence between animals from China and Australia (DA=8.4% +-2.47%) was greater than between China and South Africa (DA=5.1% +-1.80%). These results strongly suggest that Australian humpback dolphins are not S. chinensis but may represent a distinct species in their own right.