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| Titel |
Diatom DNA as historical information |
| VerfasserIn |
K. R. Stoof, L. S. Epp, M. H. Trauth, R. Tiedemann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021904
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| Zusammenfassung |
| This survey is about the reconstruction of paleo environmental conditions in East Africa
using recent and historic lakes sediments of shallow lakes in Kenya. This interdisciplinary
approach combines the molecular analysis of ancient diatom DNA and the morphological
analysis of diatom assemblages of short sediment cores to reveal the potential of molecular
genetics in geosciences.
This study comprises the investigation of two short sediment cores from Lake Naivasha
(Kenya) taken in 2007, covering a stretch of ca. 80 years. Several sediment slices were
analysed by molecular methods that concludes in species identification based on DNA
fragments. Therefore total DNA was extracted and applied to a diatom DNA specific PCR
amplifying a gene fragment that is frequently used for species identification. After cloning
PCR products, clones were sequenced, sequences from different diatom species were
analysed. As a comparison permanent slides were prepared for each sediment sample for
counting diatom valves.
The results suggest that DNA damage, perhaps species depended, and specific factors of
PCR contribute to an overhang of two dominant diatom species (Aulacoseira ambigua
and Aulacoseira granulata) represented by the molecular approach whereas rare
species seen by light microscopy are not yet identifiable with molecular methods.
Moreover changes in diatom assemblages and the reconstructed conductivity indicate a
decrease of lake level around 1940. This shift seems to be also represented in the
molecular approach as a decrease in the amount of diverse diatom DNA sequences
found, what is probably caused by worse DNA preservation conditions at that time. |
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