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Bacteria in the lichen symbiosis
Moťková, Eliška ; Steinová, Jana (advisor) ; Peksa, Ondřej (referee)
This thesis summarizes the most recent research on bacteria in lichen symbiosis. Lichen symbiosis and the partners participating in it are described in the first part of the thesis. The emphasis is mainly on the different functions that bacteria can have in lichen symbiosis. These functions include, for example, the fixation of atmospheric nitrogen, the production of cobalamin, essential for the growth of some algae, the secretion of antimicrobial substances and the recycling of nutrients contained in old parts of the litter. The main groups of bacteria that occur in the lichen symbiosis are also discussed, along with the factors that influence their occurrence. The most abundant group of bacteria in lichens are the Alphaproteobacteria. Their abundance in lichens is probably influenced by the frequent occurrence of these bacteria in the substrate on which the lichen grows. Other abundant groups of bacteria in lichens are representatives of Firmicutes, actinobacteria or acidobacteria. All important groups of bacteria are acquired by lichens through both vertical transfer and horizontal transfer. Key words: Alphaproteobacteria, nitrogen fixation, antagonistic activity, microbiota, biofilm
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Impacts of global climate change on lichens
Šubrtová, Tereza ; Malíček, Jiří (advisor) ; Peksa, Ondřej (referee)
Lichens, also known as lichenized fungi, are primarily known as excellent indicators of environmental change. Due to climate change, lichens are increasingly being studied for their indication and prediction of individual factors of global climate change. In the first part of this work, individual abiotic factors affecting lichens on a global scale are examined, to understand these factors in all possible environments. The next part of the work focuses on Europe and addresses the history of the development and future prediction of lichen distribution under the influence of climate change. The end of the work is focused on the territory of the Czech Republic and mentions the most affected species in our area. The study of global climate change on lichens is important not only for understanding the effects of environmental changes on organisms but also for proper prioritization of nature protection leading to a halt in the decline of species and their habitats.
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Let's meet in the littoral: Diversity of symbiosis in the Verrucariaceae lichens
Schmidtová, Jana ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
Lichens are organisms formed by several symbiotic partners, most importantly a fungus (mycobiont) and an alga or cyanobacteria (photobiont). Although most lichens are terrestrial, some can be found also in aquatic environments. Black crustose lichens from the family Verrucariaceae (Verrucariales, Eurotiomycetes, Ascomycota) were able to adapt to this environment very well and often dominate in the seashore near fluctuating water level. The ability of these lichens to inhabit various environments is associated with their unusually wide range of photobionts. However, this symbiont is not known to most of them. This work investigates the diversity of lichens of the family Verrucariaceae in the littoral zone of the Baltic and the North Sea coasts, the relationships between symbionts and the connection between lichen diversity and the salinity gradient. Using metabarcoding, the diversity of free-living algae in the vicinity of the studied lichens is determined and the symbiotic algae are compared with the photobionts found in the lichens. Mycobionts and photobionts were identified using ITS and 18S rDNA. A total of nine lineages of mycobionts and photobionts were found. The most common lichen turned out to be the species Hydropunctaria maura with its photobiont Pseudendoclonium submarinum. For several...
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The efect of environmental variables on diversity of lichen photobionts
Červenková, Tereza ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
Lichens represent a synergistic combination of at least two organisms, a heterotrophic fungus and a photosynthetic alga or a cyanobacterium. This association has resulted in a symbiotic organism, which is well tolerant to environmental influences. In fact, symbiotic relationship provides mutual benefit for both organisms. It is generally well known that the fungal partners of lichens are far less sensitive to environmental conditions, such as the temperature, altitude, rainfall or the type and composition of the substrate, in comparison to their algal partners. Therefore, lichen forming fungi have much wider ecological valences than the photobionts interacting with them. Indeed, most of the photosyntetic genera and species are adapted only to certain environmental conditions. For this reason, the symbiotic algae and cyanobacteria probably play a major role during the initial lichen formation on the site. This thesis focuses on the adaptability of photoautotrophic symbionts of lichens, coccoid green algae and cyanobacteria, to environmental conditions. Ecological diversification of photobionts has a direct impact on their genetic differentiation and thus to differentiate lichen species themselves. Unfortunately, in many studies the authors mostly dealt with the diversity of macroscopic symbiotic...
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Epiphytic lichens of the Czech Republic
Pelechová, Kateřina ; Svoboda, David (advisor) ; Peksa, Ondřej (referee)
This bachelor thesis researches the works of the years 1908-2013, which deal with the occurrence of epiphytic, i.e. growing on tree species, lichens in the Czech Republic. In the introduction there is briefly interpreted definition of lichens and epiphytes and the relationship between lichens and heir environment (with an emphasis on air pollution) is described. The main part is devoted to the processing of data found in the literature - when and on which tree species is the lichen growing - and is divided into two periods (1908-1970 and 1971-2013). The frequency of lichen species changes between periods - links between lichens and tree species and preference of the species and its changes over time, changes in preference of pH of bark of trees and tree species with the highest number of species of lichens. The study contains a list of 429 lichen species occurring on tree species in the Czech Republic. Powered by TCPDF (www.tcpdf.org)
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Biotic interactions in epiphytic lichen communities
Černajová, Ivana ; Svoboda, David (advisor) ; Peksa, Ondřej (referee)
The objective of my bachelor's thesis is to review available literature on biotic interactions in epiphytic lichen communities. At first the epiphytic habitat is defined. The next part deals with the interactions, specifically competition and predation. Lichens compete for light and space among each other and with other cryptogams at the same time. There are a few known mechanisms of competition, most of them being based on overgrowing of thalli and chemical action. Thallus morphology, growth rate and content of allelochemicals are the main traits determining success in competition. Competitive abilities depend on various abiotic factors as well as on total composition of the community. Lichens are forced to invest in chemical defence by the presence of herbivores and parasites. Distribution of the defence substances matches the optimal defence theory. There is numerous evidence that biotic interactions modify characteristics of both individuals and species, mainly considering the secondary metabolites content and the width of the realized ecological niche. Competitors and predators may determine species distribution. The thesis summarises the knowledge of the mechanism, character and impact of the competition and predation in epiphytic lichen communities. Key words: lichens, cryptogams, epiphytes,...
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Lichens and (heavy) metals
Hrdinová, Aneta ; Peksa, Ondřej (advisor) ; Malíček, Jiří (referee)
My thesis is focused on liches and heavy metals. In first part includes the general characteristics of lichens, the short description of their biology, morphology and anatomy. The next part is focused on the characteristics of the methods of absorption of metals by lichens, their physiological effects on the body and the mechanisms of defense against the toxicity of metals lichens. The work includes the list of species of lichen, and their relationships to particular heavy metals. Key words: Lichens, heavy metals, metal tolerance, detoxification, copper
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