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For long, microorganisms have been thought to have unlimited dispersal and therefore to follow fundamental different assembly rules than macroorganisms. This premise is slowly changing, and ecological structure of microbial communities could gain insights from the theoretical and methodological developments applied on macroorganisms. While scarcely used, functional and phylogenetic metrics represent complement facets of diversity that should add valuable information to understand microorganisms' diversity structuration. We used freshwater phytobenthic algae desmids (Desmidiaceae, Streptophyta) as a model group. The main aim of this thesis was identification the processes creating distinct patterns of desmid diversity using functional and phylogenetical information. We sampled over a hundred communities within Europe, used a well-resolved phylogeny, and size- related functional traits. Moreover, we experimentally measured the population growth rate of desmids, to determine the link between functional traits and organism performance. Desmid communities showed non-random patterns of size and phylogenetic distributions on both large and local scales, advocating for a strong influence of niche-based processes. At large scale, desmids were distributed into environmentally and geographically separated...

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This work deals with the issue of the revitalization of harvested peat lands. Peat lands dominated by bryophyte Sphagnum do not readily return to their natural stages. In the theoretical part I conclude a) experience with restoring the hydrological regime and b) successes in revegetation by typical peat land vegetation, which is the essential pre-requisite for developing functional peat land ecosystem. The practical part is focused on my own research of diversity and ecology of algaes at cut-away and later restored peat land Babín in the vicinity of Žďár nad Sázavou. These samples of phytobenthos were collected over a tre year span from 2007 to 2009. I have examined the diversity of these samples by optical microscope, using the data I collected about species abundance for multidimensional statistical analysis.

This work deals with competition as well as mechanisms of coexistence of species. The introduction presents comtemporary coexistence theory. There are two types of differences - niche and relative fitness differences. Fitness differences increase inter-species competition. This is a novell result, current theory expected differences decrease competition in any case. This work summarized results of experimental works that have investigated various aspects of co- existence theory, with special focus on protists. Competition was found to be an important mechanism in creating patterns of community assembly, unfortunately drawing common results is complicated. According to competition-relatedness hypotheses, within some competition lines competition decreased with relatedness. This relation however does not hold always. There are two conditions: functional traits must bear a phylogenetic signal and must be evolutionally conserved. Studies on protists imply that higher number of species should be included instead of pairwise combination tests in order to get valid information on relation of species. This could be similar for traits. Plants experiments have shown that competition may be affected by traits only in complex systems with a number of traits included. Such experiment involving protists have...

The genus Micrasterias comprises one of the most beautiful organisms. It attracts, due to its spectacularly shaped cells, the attention of scientist and amateur biologist almost for almost 200 years. This thesis summarizes the current knowledge about these extraordinary organisms. The first part deals with the morphology and the life cycle of these algae. They share a unique type of reproduction (conjugation) with the other representatives of the class Zygnematophyceae. The second part concerns phylogeny of this genus. Several morphologically distinct species have been revealed with the aid of molecular phylogenetic methods to belong to the genus Micrasterias. A polyphasic evaluation of three species complexes within this genus also revealed an extensive hidden diversity. The last chapters summarize the knowledge about the influence of hidden diversity and accelerated morphological evolution on our understanding of diversity and biogeography of these organisms.