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Genetic divergences pre-date Pleistocene glacial cycles in the New Zealand speckled skink, Oligosoma infrapunctatum

Authors

  • Stephanie N. J. Greaves,

    1. Allan Wilson Centre for Molecular Ecology & Evolution, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
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  • David G. Chapple,

    Corresponding author
    1. Allan Wilson Centre for Molecular Ecology & Evolution, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
      *David Chapple, Herpetology Section, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001, Australia. E-mail: dchapple@museum.vic.gov.au
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    • Present address: Herpetology Section, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001, Australia.

  • Charles H. Daugherty,

    1. Allan Wilson Centre for Molecular Ecology & Evolution, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
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  • Dianne M. Gleeson,

    1. Ecological Genetics Laboratory, Landcare Research, Auckland, New Zealand
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  • Peter A. Ritchie

    1. Allan Wilson Centre for Molecular Ecology & Evolution, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
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*David Chapple, Herpetology Section, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001, Australia. E-mail: dchapple@museum.vic.gov.au

Abstract

Aim  To examine the hypothesis raised by Graham S. Hardy that Pleistocene glacial cycles suffice to explain divergence among lineages within the endemic New Zealand speckled skink, Oligosoma infrapunctatum Boulenger.

Location  Populations were sampled from across the entire range of the species, on the North and South Islands of New Zealand.

Methods  We sequenced the mitochondrial genes ND2 (550 bp), ND4 + tRNAs (773 bp) and cytochrome b (610 bp) of 45 individuals from 21 locations. Maximum likelihood, maximum parsimony and Bayesian methods were used for phylogenetic reconstruction. The Shimodaira–Hasegawa test was used to examine hypotheses about the taxonomic status of morphologically distinctive populations.

Results  Our analysis revealed four strongly supported clades within O. infrapunctatum. Clades were largely allopatric, except on the west coast of the South Island, where representatives from all four clades were found. Divergences among lineages within the species were extremely deep, reaching over 5%. Two contrasting phylogeographical patterns are evident within O. infrapunctatum.

Main conclusions  The deep genetic divisions we found suggest that O. infrapunctatum is a complex of cryptic species which diverged in the Pliocene, contrary to the existing Pleistocene-based hypothesis. Although Pleistocene glacial cycles do not underlie major divergences within this species, they may be responsible for the shallower phylogeographical patterns that are found within O. infrapunctatum, which include a radiation of haplotypes in the Nelson and Westland regions.

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