Testing for endemism, genotypic diversity and species concepts in Antarctic terrestrial microalgae of the Tribonemataceae (Stramenopiles, Xanthophyceae)

Authors

  • Nataliya Rybalka,

    1. Taras Shevchenko National University, Department of Botany, Volodymyrska 64, 01017 Kiev, Ukraine.
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  • Robert A. Andersen,

    1. Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine 04575, USA.
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  • Igor Kostikov,

    1. Taras Shevchenko National University, Department of Botany, Volodymyrska 64, 01017 Kiev, Ukraine.
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  • Kathrin I. Mohr,

    1. Experimentelle Phykologie und Sammlung von Algenkulturen, Georg-August-Universität, Untere Karspüle 2, 37073 Göttingen, Germany.
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  • Andrzej Massalski,

    1. Jan Kochanowski University of Art and Natural Sciences, Biology Institute, Department of Botany, 15 Swietokrzyska, 25-406 Kielce, Poland.
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  • Maria Olech,

    1. Jagiellonian University, Institute od Botany, Zdzisław Czeppe Department of Polar Research and Documentation, Kopernika 27, 31-501 Kraków, Poland.
    2. Polish Academy of Sciences, Department of Antarctic Biology, Ustrzycka 10/12, 02-141 Warszawa, Poland.
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  • Thomas Friedl

    Corresponding author
    1. Experimentelle Phykologie und Sammlung von Algenkulturen, Georg-August-Universität, Untere Karspüle 2, 37073 Göttingen, Germany.
      *E-mail tfriedl@uni-goettingen.de; Tel. (+49) 551 397868; Fax (+49) 551 397871.
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*E-mail tfriedl@uni-goettingen.de; Tel. (+49) 551 397868; Fax (+49) 551 397871.

Summary

The genetic diversity of all available culture strains of the Tribonemataceae (Stramenopiles, Xanthophyceae) from Antarctica was assessed using the chloroplast-encoded psbA /rbcL spacer region sequences, a highly variable molecular marker, to test for endemism when compared with their closest temperate relatives. There was no species endemic for Antarctica, and no phylogenetic clade corresponded to a limited geographical region. However, species of the Tribonemataceae may have Antarctic populations that are distinct from those of other regions because the Antarctic strain spacer sequences were not identical to sequences from temperate regions. Spacer sequences from five new Antarctic isolates were identical to one or more previously available Antarctic strains, indicating that the Tribonemataceae diversity in Antarctic may be rather limited. Direct comparisons of the spacer sequences and phylogenetic analyses of the more conserved rbcL gene revealed that current morphospecies were inadequate to describe the actual biodiversity of the group. For example, the genus Xanthonema, as currently circumscribed, was paraphyletic. Fortunately, the presence of distinctive sequence regions within the psbA/rbcL spacer, together with differences in the rbcL phylogeny, provided significant autoapomorphic criteria to re-define the Tribonemataceae species.

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