One species or two? Vicariance, lineage divergence and low mtDNA diversity in geographically isolated populations of South Asian river dolphin

G. T. Braulik, R. Barnett, V. Odon, V. Islas-Villanueva, A. R. Hoelzel, J. A. Graves

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Despite their endangered status, the taxonomic relationship between the two geographically isolated South Asian river dolphin populations has never been comprehensively assessed and remains contentious. Here we present the first dedicated evaluation of the molecular phylogenetic relationship between the Indus (Platanista gangetica minor) and Ganges (Platanista gangetica gangetica) River dolphins using mitochondrial DNA from the control region and cytochrome b, extracted from museum specimens. The 458 bp partial control region sequences from 26 Indus River dolphin samples exhibited no variation. Only six haplotypes were identified in the 31 (18 Indus; 13 Ganges) complete (856 bp) control region sequences obtained, none were shared between subspecies, and there were five fixed differences between them. Similarly low genetic diversity was found in a 541 bp section of the cytochrome b gene (n = 29). The lack of shared haplotypes and fixed differences resulted in ΦST for the partial control region sequences of 0.932 (p < 0.0001) and FST of 0.843 (p  < 0.0001), indicating the long-term absence of gene flow and clear genetic differentiation between the two geographically isolated populations. An externally calibrated molecular clock estimated that Indus and Ganges dolphins diverged around 550,000 years ago (95 % posterior probability 0.13–1.05 million years ago), possibly when dolphins from the Ganges dispersed into the Indus during drainage capture.
Original languageEnglish
Pages (from-to)111-120
Number of pages10
JournalJournal of Mammalian Evolution
Volume22
Issue number1
Early online date18 May 2014
DOIs
Publication statusPublished - Mar 2015

Keywords

  • Molecular phylogeny
  • Taxonomy
  • Platanista gangetica
  • Molecular diversity
  • Systematics
  • River capture

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