Abstract for presentation at Biodiversity Extinction Crisis Conference - A Pacific Response

Uncovering hidden biodiversity: DNA taxonomy and the discovery of new whale species

  • Merel Dalebout, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Kensington, NSW 2052, Australia, Australia
  • Scott Baker, Marine Mammal Program, Hatfield Marine Science Center, Oregon State University, Newport, Oregon, USA, United States
  • Debbie Steel, Marine Mammal Program, Hatfield Marine Science Center, Oregon State University, Newport, Oregon, USA, United States
  • William Perrin, Southwest Fisheries Science Center, US National Marine Fisheries Service, La Jolla, California, USA, United States
  • James Mead, US National Museum of Natural History, Smithsonian Institution, Washington DC, USA, United States

    • DNA taxonomy can be a very powerful tool for uncovering hidden biodiversity. However, the effectiveness of this approach is largely reliant on a lack of overlap between intra-specific diversity and inter-specific divergence (a ‘barcoding gap’). The discovery of a divergent DNA lineage can provide preliminary evidence for the existence of an unrecognised species or subspecies, but the identification of such a lineage assumes that within-specific variation has been adequately sampled. Using two mitochondrial DNA (mtDNA) fragments, the control region (CR) and cytochrome b (CYB), we test the robustness of the barcoding gap for a speciose genus of rare whales, _Mesoplodon_ (beaked whales). Sequences were generated from an average of five individuals for each of the 14 known _Mesoplodon_ species. Average intra-specific diversity was found to be low (CR, 0.6% +/- 0.06%; CYB, 0.8% +/- 0.09%) relative to inter-specific divergence (CR, 7.4% +/- 0.04%; CYB, 11.8% +/- 0.04%) with little overlap. All _Mesoplodon_ species recognised previously from morphological characters were found to be genetically distinct, and possessed a minimum of two diagnostic sites (nucleotide substitutions) that distinguished them from all other species in the genus. Further, all sequences formed strongly-supported, species-specific clades in phylogenetic reconstructions, each of which was reciprocally monophyletic with respect to all other such clades. Overall, these mtDNA markers appear to be very well suited to species identification in this genus under the Phylogenetic Species Concept. Recently, we discovered a divergent DNA lineage among beaked whales from the Tropical Pacific which could represent a new species. The taxonomic status of this lineage will be considered in light of additional information from nuclear introns and the morphological characteristics of the specimens in question.

    Conference Organiser - ICMS Pty Ltd