Conservation Genetics

, Volume 13, Issue 4, pp 987–1002 | Cite as

Genetic differentiation and limited gene flow among fragmented populations of New Zealand endemic Hector’s and Maui’s dolphins

  • Rebecca M. Hamner
  • Franz B. Pichler
  • Dorothea Heimeier
  • Rochelle Constantine
  • C. Scott Baker
Research Article

Abstract

Gene flow among small fragmented populations is critical for maintaining genetic diversity, and therefore the evolutionary potential of a species. Concern for two New Zealand endemic subspecies, the Hector’s (Cephalorhynchus hectori hectori) and Maui’s (C. h. maui) dolphins, arises from their low abundance, slow rate of reproduction, and susceptibility to fisheries-related mortality. Our work examined genetic differentiation and migration between the subspecies and among regional and local Hector’s dolphin populations using mitochondrial (mt) DNA and microsatellite genotypes from 438 samples. Results confirmed earlier reports of a single unique mtDNA control region haplotype fixed in the Maui’s dolphin, and provided new evidence of reproductive isolation from Hector’s dolphins (9-locus microsatellite FST = 0.167, P < 0.001). Independent evolutionary trajectories were also supported for Hector’s dolphin populations of the East Coast, West Coast, Te Waewae Bay and Toetoe Bay. Low asymmetrical migration rates were found among several Hector’s dolphin populations and assignment tests identified five Hector’s dolphins likely to have a migrant father from another regional population. There appears to be sufficient step-wise gene flow to maintain genetic diversity within the East and West Coasts; however, the two local South Coast populations exhibited a high degree of differentiation given their close proximity (~100 km). To maintain the evolutionary potential and long-term survival of both subspecies, genetic monitoring and conservation management must focus on maintaining corridors to preserve gene flow and prevent further population fragmentation and loss of genetic diversity, in addition to maintaining local population abundances.

Keywords

Gene flow Migration Microsatellites mtDNA control region Cephalorhynchus hectori 

Supplementary material

10592_2012_347_MOESM1_ESM.pdf (94 kb)
Supplementary material 1 (PDF 94 kb)
10592_2012_347_MOESM2_ESM.pdf (402 kb)
Supplementary material 2 (PDF 402 kb)

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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Rebecca M. Hamner
    • 1
    • 2
  • Franz B. Pichler
    • 2
  • Dorothea Heimeier
    • 2
  • Rochelle Constantine
    • 2
  • C. Scott Baker
    • 1
    • 2
  1. 1.Marine Mammal Institute and Department of Fisheries and WildlifeOregon State UniversityNewportUSA
  2. 2.School of Biological SciencesUniversity of AucklandAucklandNew Zealand

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