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Unveiling hidden species diversity in desmids (Desmidiales, Viridiplantae)
Šťastný, Jan ; Neustupa, Jiří (advisor) ; F.M. Coesel, Peter (referee) ; Kaštovský, Jan (referee)
The delineation of desmid species was traditionally based on purely morphological features. However, a frequent misinterpretation of morphological variability in desmids has led in the past to extensive taxonomical confusion within this important group of green algae which complicates the interpretation of their biodiversity in freshwater ecology, biogeography and biomonitoring. Consequently, I focused in this thesis predominantly on a previously neglected issue, the application of polyphasic approaches in the species-level taxonomy of desmids. In the most studies, a combination of both traditional morphological and modern molecular phylogenetic and geometric morphometric methods has been used to evaluate the taxonomy of selected desmid species, particularly representatives of the morphologically complex genera Micrasterias and Xanthidium. In two papers, I used the combination of traditional morphological and autecological data to clear up the taxonomy of several morphologically less prominent desmid taxa. Generally, the results of the thesis demonstrated that the way we recently see the diversity and distribution of desmids should be thoroughly changed. The real species diversity is mostly distinctly finer than that estimated by classical morphological taxonomy, often corresponds to varieties of...
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The phylogenetic structure of desmid communities
Bestová, Helena ; Škaloud, Pavel (advisor) ; Mareš, Jan (referee)
Abstract This diploma thesis focuses on processes that structure desmid communities. Phylogenetic structure of communities helps to reveal those processes. Phylogenetic structures links ecology of communities and evolutionary history of species in those communities. Totally I analysed 89 desmid communities. Most of them were phylogenetically structured, which agrees with the hypothesis that communities are structured by classical niche-related processes, such as competition and environmental filtering. Usage of environmental information showed the influence of pH on the community structure. Low pH acts as a strong environmental filter. Under the influence of this filter communities are composed of closely relates species. In the absence of this filter communities are structured by competition. Localities with higher pH host communities of distantly related species - phylogenetically overdispersed. There was found no influence of conductivity and geographical distance on phylogenetic structure of desmids communities. Key words: phylogenetic structure, desmids, Desmidiales, environmental filtering, pH
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Distribution, diversity and ecology of benthic desmids along local spatial scale
Svoboda, Pavel ; Šťastný, Jan (advisor) ; Řeháková, Klára (referee)
Besides spatial heterogeneity, an important component of diversity of the protist communities is also the variation in species assemblages through time (temporal turnover). Spatial and temporal variation in patterns of distribution and abundance of lentic microphytobenthos assemblages is often large and occurs at relatively small spatial scale. Desmids (Zygnematophyceae) often constitute a characteristic part of the microphytobenthos of peat bogs. Despite their important role in primary production and fact that they are useful indicators of ecosystem uniqueness, investigations of their seasonality and spatial distribution are scarce. In my thesis I have investigated if desmid epipelic communities are driven rather by neutral or niche-based processes, and I also focused on the factors affecting their diversity, seasonal dynamics and spatial patterns at the local spatial scale. The study was conducted at the two different types of biotopes - minerotrophic lowland peat bogs (Doksy region) and ombrotrophic raised bogs (Jizera Mountains region). Seasonal changes in species composition and diversity of assemblages were not evident. This may be affected by a monopolization effect and also that local abundance of species was positively correlated with population persistence, which suggests that high local...
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