Reappraisal of the sub species hypothesis for Gangetic dolphins based on mitochondrial genomics

Abstract The Gangetic dolphin, P. gangetica, is one of the oldest known creatures, and its taxonomic status has been debated for over two centuries with no agreement. The clarification of the systematic relationships of Platanista taxa has been listed as among the highest priority for all cetaceans. Of the several taxonomic schemes proposed, all have been very limited and do not provide sufficient weight of evidence to defend any taxonomic classification. Consequently, to resolve this case, a new mitochondrial genome record for P. gangetica gangetica was created for quantitative evaluation of the Ganges and Indus River dolphin populations to estimate species boundaries. This has aided in the resolution of the taxonomic status of the Gangetic dolphin, P. gangetica by showing that the subspecies P. gangetica gangetica and P. gangetica minor are indistinguishable based on the molecular differences and do not follow the standards for molecular species boundaries. Also geographic historical reviews show that these two populations were one during the Miocene era, and that segregation occurred during the geosyncline effect of the Bay of Bengal. However, with the present set of evidences, we propose to abandon the subspecies hypothesis for these P. gangetica taxa.