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The use of diatoms (Bacillariophyta) in paleolimnology
Aubrechtová, Martina ; Kulichová, Jana (advisor) ; Píšková, Anna (referee)
This thesis is a literature review summarizing methodology and the possibility of use of diatoms (Bacillariophyta) for paleoecological reconstructions of extinct lacustrine ecosystems. In addition, the theoretical part of the thesis is devoted to basic characteristics, evolutionary history and ecology of the group, lakes and the fossil record. In the practical part, two samples of sediments of a fossil lake that has been discovered and studied within the Morava Project in Strážnické Pomoraví are compared.
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The significance of silica structures in chromist microorganisms.
Nováková, Dora ; Škaloud, Pavel (advisor) ; Němcová, Yvonne (referee)
The silica is one of the most common elements in the Earth's crust. During erosion it is released in soluble form to the environment, where some organisms can accumulate the silica and incorporate it to their bodies by biosilicification process. The organsims possessing this ability are widespread either when considering their position in eukaryotic tree of life, or their abundance in natural ecosystems. As a result, the whole global biogeochemical cycle of silica is controlled by biosilicificated organisms. In Chromista microorganisms, the silica is loaded to so-called "silica deposition vesicles" - membrane surrounded compartments, in which the silica is polymerated and formed into the final shape of silica structures during an ingeniously controlled in vivo process. Apparent differences in the process of silica deposition among Chromista microorganisms imply that this ability has developed independenty and repeatedly within the group. The most common silica structures are scales, bristles, cases, skeletons and cysts. The analogical structures often originated independently in unrelated lines of Chromista by means of convergent evolution. On the contrary, in some lineages of Chromista, the ability of biosilicification was suppressed. It is therefore very likely that the silica structures should...
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The significance of silica structures in chromist microorganisms.
Nováková, Dora ; Škaloud, Pavel (advisor) ; Němcová, Yvonne (referee)
The silica is one of the most common elements in the Earth's crust. During erosion it is released in soluble form to the environment, where some organisms can accumulate the silica and incorporate it to their bodies by biosilicification process. The organsims possessing this ability are widespread either when considering their position in eukaryotic tree of life, or their abundance in natural ecosystems. As a result, the whole global biogeochemical cycle of silica is controlled by biosilicificated organisms. In Chromista microorganisms, the silica is loaded to so-called "silica deposition vesicles" - membrane surrounded compartments, in which the silica is polymerated and formed into the final shape of silica structures during an ingeniously controlled in vivo process. Apparent differences in the process of silica deposition among Chromista microorganisms imply that this ability has developed independenty and repeatedly within the group. The most common silica structures are scales, bristles, cases, skeletons and cysts. The analogical structures often originated independently in unrelated lines of Chromista by means of convergent evolution. On the contrary, in some lineages of Chromista, the ability of biosilicification was suppressed. It is therefore very likely that the silica structures should...
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The use of diatoms (Bacillariophyta) in paleolimnology
Aubrechtová, Martina ; Píšková, Anna (referee) ; Kulichová, Jana (advisor)
This thesis is a literature review summarizing methodology and the possibility of use of diatoms (Bacillariophyta) for paleoecological reconstructions of extinct lacustrine ecosystems. In addition, the theoretical part of the thesis is devoted to basic characteristics, evolutionary history and ecology of the group, lakes and the fossil record. In the practical part, two samples of sediments of a fossil lake that has been discovered and studied within the Morava Project in Strážnické Pomoraví are compared.
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