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Hidden diversity in diatoms of Kenyan Lake Naivasha: a genetic approach detects temporal variation

Authors

  • KATHLEEN R. STOOF-LEICHSENRING,

    1. Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Strasse 24-25, Haus 26, D-14476 Potsdam, Germany
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  • LAURA S. EPP,

    1. National Centre for Biosystematics, Natural History Museum, University of Oslo, Oslo, Norway
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  • MARTIN H. TRAUTH,

    1. Institute of Earth and Environmental Science, University of Potsdam, Potsdam, Germany
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  • RALPH TIEDEMANN

    1. Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Strasse 24-25, Haus 26, D-14476 Potsdam, Germany
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Kathleen R. Stoof-Leichsenring, Fax: 0049-331-9775070; E-mail: stoof@uni-potsdam.de

Abstract

This study provides insights into the morphological and genetic diversity in diatoms occurring in core sediments from tropical lakes in Kenya. We developed a genetic survey technique specific for diatoms utilizing a short region (76–67 bp) of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene as genetic barcode. Our analyses (i) validated the use of rbcL as a barcoding marker for diatoms, applied to sediment samples, (ii) showed a significant correlation between the results obtained by morphological and molecular data and (iii) indicated temporal variation in diatom assemblages on the inter- and intra-specific level. Diatom assemblages from a short core from Lake Naivasha show a drastic shift over the last 200 years, as littoral species (e.g. Navicula) are replaced by more planktonic ones (e.g. Aulacoseira). Within that same period, we detected periodic changes in the respective frequencies of distinct haplotype groups of Navicula, which coincide with wet and dry periods of Lake Naivasha between 1820 and 1938 AD. Our genetic analyses on historical lake sediments revealed inter- and intra-specific variation in diatoms, which is partially hidden behind single morphotypes. The occurrence of particular genetic lineages is probably correlated with environmental factors.

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