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The phylogeography of dusky dolphins (Lagenorhynchus obscurus): a critical examination of network methods and rooting procedures
Cassens, I.; Van Waerebeek, K.; Best, P.B.; Crespo, E.A.; Reyes, J.; Milinkovitch, M.C. (2003). The phylogeography of dusky dolphins (Lagenorhynchus obscurus): a critical examination of network methods and rooting procedures. Mol. Ecol. 12(7): 1781-1792.
In: Molecular Ecology. Blackwell: Oxford. ISSN 0962-1083, more
Peer reviewed article  

Available in  Authors 
    VLIZ: Open Repository 243213 [ OMA ]

Author keywords
    Cetacea; conservation genetics; mtDNA; network methods; phylogeography; rooting techniques

Authors  Top 
  • Cassens, I.
  • Van Waerebeek, K., more
  • Best, P.B.
  • Crespo, E.A.
  • Reyes, J.
  • Milinkovitch, M.C., more

    We investigated the phylogeography and evolutionary history of dusky dolphins (Lagenorhynchus obscurus) using DNA sequences of the full mitochondrial cytochrome b gene in 124 individuals from the putative stocks off Peru, Argentina and Southwest Africa. While genetic differentiation within oceans is surprisingly low, there is no evidence for recent female gene flow between Atlantic and Pacific waters. Highest genetic variability in terms of sequence divergence and number of haplotypes is found in the Atlantic. Our analyses also indicate that the eastern South Pacific dusky dolphins stock should be considered a separate management unit. Given the high level of mortality experienced by the Peruvian dusky dolphin in local fishery activities, these findings have important implications for an objective management of the species. Furthermore, we analysed our mitochondrial sequence data with several widely used network estimation and rooting methods. The resulting intraspecific gene genealogies and rooting inferences exhibited substantial differences, underlying the limitations of some algorithms. Given that scientific hypotheses and management decisions depend strongly on inferred tree or network topologies, there is a clear need for a systematic comparative analysis of available methods. Finally, the present study indicates that (i) the dusky and the Pacific white-sided dolphins are sister species and (ii) not only the Westwind Drift hypothesis but also other models of dispersion are compatible with the current geographical distribution of dusky dolphins.

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