Thursday, October 31, 2013

[Cetology • 2013] A New Humpback Dolphin Species (Sousa sp. nov.) in Australian Waters?: Integrating Multiple Lines of Evidence to Better Understand the Evolutionary Divergence of Humpback Dolphins along their Entire Distribution Range



A newly identified species of Humpback dolphin, Sousa sp. nov.,
strongly resembles Sousa chinensis (Indo-Pacific Humpback dolphin), shown here
photo: Susan Crocetti | http://wetlandinfo.ehp.qld.gov.au

Abstract
The conservation of humpback dolphins, distributed in coastal waters of the Indo-West Pacific and eastern Atlantic Oceans, has been hindered by a lack of understanding about the number of species in the genus (Sousa) and their population structure. To address this issue, we present a combined analysis of genetic and morphologic data collected from beach-cast, remote-biopsied and museum specimens from throughout the known Sousa range. We extracted genetic sequence data from 235 samples from extant populations and explored the mitochondrial control region and four nuclear introns through phylogenetic, population-level and population aggregation frameworks. In addition, 180 cranial specimens from the same geographical regions allowed comparisons of 24 morphological characters through multivariate analyses. The genetic and morphological data showed significant and concordant patterns of geographical segregation, which are typical for the kind of demographic isolation displayed by species units, across the Sousa genus distribution range. Based on our combined genetic and morphological analyses, there is convincing evidence for at least four species within the genus (S. teuszii in the Atlantic off West Africa, S. plumbea in the central and western Indian Ocean, S. chinensis in the eastern Indian and West Pacific Oceans, and a new as-yet-unnamed species off northern Australia).

Keywords: conservation genetics, mammals, molecular evolution, speciation, humpback dolphins, cetaceans


Sousa chinensis (Indo-Pacific Humpback dolphin)
photo: Susan Crocetti | http://wetlandinfo.ehp.qld.gov.au


Martin Mendez, Thomas J. Jefferson, Sergios-Orestis Kolokotronis, Michael Krützen, Guido J. Parra, Tim Collins, Giana Minton, Robert Baldwin, Per Berggren, Anna Särnblad, Omar A. Amir, Vic M. Peddemors, Leszek Karczmarski, Almeida Guissamulo, Brian Smith, Dipani Sutaria, George Amato and Howard C. Rosenbaum. 2013. Integrating Multiple Lines of Evidence to Better Understand the Evolutionary Divergence of Humpback Dolphins along their Entire Distribution Range: A New Dolphin Species in Australian Waters? Molecular Ecology, published online October 29, 2013; doi: dx.doi.org/10.1111/mec.12535


New Dolphin Species Found in Australian Waters 
An international team of researchers has announced the discovery of a new species of humpback dolphin in the waters off northern Australia.
http://www.sciencedaily.com/releases/2013/10/131029143000.htm
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