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Mechanisms structuring host-parasitoid communities in a global warming perspective
THIERRY, Mélanie Jeanne
Ecological communities are composed of a multitude of interacting species, and the outcome of pairwise interactions depends on other co-occurring species within the community. With current global environmental changes, both abiotic and biotic environment are changing, affecting the structure and dynamics of communities. I used a series of laboratory experiments on a set of Drosophila species and their parasitic wasps to investigate the effects of biotic and abiotic factors on interactions and communities. I first compared the outcome of host-parasitoid interactions across community modules commonly found in host-parasitoid communities (i.e., pairwise interaction, exploitative competition, apparent competition, and both exploitative and apparent competition). I found generally higher host suppression with multiple parasitoid species, but species-specific effects for parasitoid performance. I then observed that warming impacts host communities through direct effects on species performance rather than altered competitive interactions and parasitism. Finally, I found that temperature strongly influences the effects of multiple parasitoids on host suppression across different parasitoid assemblages, suggesting a general pattern for the environmental dependence of trophic and non-trophic interactions. My thesis emphasizes the importance of considering environmental factors and different interaction types to better predict community dynamics in a rapidly changing world.
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The ecology of peatland bryophytes - adaptations and competition in alkaline fens
VICHEROVÁ, Eliška
This dissertation thesis studies adaptations and competition of peatland bryophytes in alkaline fens. Specifically, it examines the existence of plant-plant interactions through volatile organic compounds in peatland bryophytes and surveys impacts of water chemistry on composition of bryophyte communities and species survival. It also aims to resolve principles behind calcicole-calcifuge behaviour of peatland bryophytes and mechanisms behind calcium toxicity.
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Determination of methanol derivatives in drying oils
Horká, Hana ; Hraníček, Jakub (advisor) ; Janoš, Pavel (referee)
The formation of metal carboxylates is a major problem for historical and contemporary paintings, and therefore understanding the mechanism of their formation is a crucial step for developing appropriate conservation strategies and preserving the world's cultural heritage. The determination of reactive components in drying oils is an important step towards understanding the reaction mechanism. This work is aimed at developing a simple and rapid methodology for HPLC-DAD determination of low molecular weight degradation products of traditional drying oils, namely methanol, formaldehyde and formic acid. In this work, QuEChERS conditions for the extraction of methanol, formaldehyde and formic acid from various oil samples (olive, walnut, poppy and linseed oils) were optimized followed by purification of the samples from the oil matrix using a commercial d-SPE sorbent (Z-Sep/C18) and two nanostructured sorbents, CeO2 and ZrO2.
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Plant-Animal Interactions in an Inselberg Ecosystem: The Effect on Reproduction of Selected Species
Vlasáková, Blanka ; Sklenář, Petr (advisor) ; Porembski, Stefan (referee) ; Jersáková, Jana (referee)
Conclusions This thesis provides detailed insight into plant-animal relationships that are involved in reproduction of inselberg species. The results are interpreted in relation to the ecosystem functioning and they also contribute to the general knowledge on specialization in plant-animal interactions (Chapter 2 and 3), floral resources (Chapter 2, 3, and 5), pollinators' attraction (Chapter 2), relations between diaspore's characteristics and animal dispersal (Chapter 4), and conflicts among plant life stages that follow ovule fertilization (Chapter 4). As Clusia aff. sellowiana dominates the shrub vegetation, the study on its reproduction is the initial step to understanding the dynamics of the shrub patches and potential succession on the inselberg. The nocturnal pollination system of Clusia aff. sellowiana bears unusual characteristics and signs of specialization. Only one pollinator species, a cockroach Amazonina platystylata, was recorded and this species is apparently sensitive to olfactory attraction cues emitted by the flowers. This is the first evidence of pollination system that involves cockroaches as pollinators and is to some degree specialized. Clusia aff. sellowiana is dispersed by small birds. Because its diasporas are consumed by birds and there is a time lag before they are deposited,...
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Interactions of herbivore funtion gourps and Succisa pratensis
Šulcová, Hana ; Janovský, Zdeněk (advisor) ; Roubíčková, Alena (referee)
Herbivory is one of most important factors which form meadow ecosystems. These ecological communities have one of the biggest variety of species in Central Europe and their research is important in terms of management of protected species as well. Localities which has a similar importance, is also a meadow ecosystem with occurrence of Succisa pratensis, the only host plant for rare butterfly Euphydryas aurinia. Research of Succisa and its other herbivores can improve a protection of this particular butterfly. Effects of herbivores of Succisa were examined by several experiments. The first one was a field cage experiment. Its aim was to detect what kinds of herbivores (rodents and invertebrates) are involved in herbivory of leaf rosettes of Succisa and what is their impact on the fitness of these plants. The intensity of herbivory of Succisa was measured for over two vegetation seasons on the month bases. In this experiment were also examined effects of surrounding vegetation on the studied plants of Succisa. The second experiment was performed in a garden. Its aim was to clarify the role of herbivores of leaf rosettes, stalks and their interactions on the fitness of Succisa. The third experiment was concerned to true bugs, which are pre-dispersal predators of seeds of Succisa. Their effects on...
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Carnivores and ungulates in Mid-European landscape
Podhůrská, Marie ; Horáček, Ivan (advisor) ; Hart, Vlastimil (referee)
Carnivores and ungulates in Mid-European landscape Abstract The paper provides a brief survey of abundance status and population trends for most species of large mammals distributed in the Czech Republic. Abundance dynamics during past decades is discussed based on hunter statistic records covering both yearly data on hunting bags and standardized accounts of spring abundance of game animals from gamekeeper's evidence. It is documented that most of the species including regularly hunted ungulates, most of mesocarnivores and currently expanding species (racoon dog, racoon) are undergoing fluent population density increase contrasting with decrease of abundance of smaller to medium sized forms (hare, rabbit, marten, polecat). The respective data suggest that recently the community structure of large mammals has undergone considerable rearrangements. The monitoring of such phenomena is worth of a serious zoological research. The paper discussed methodological issues for such studies with particular attention to techniques of monitoring with aid of automated camera traps. Relations of the recorded faunal changes and landscapes rearrangements during past decades are also discussed. The paper is supplementing with a brief summary of two-year camera trap study in Brdy Mts. Key words: carnivora and ungulates,...
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The influence of humic acids methylation on the interaction of surface active agents
Bělušová, Anna ; Weidlich, Tomáš (referee) ; Smilek, Jiří (advisor)
The presented diploma thesis deals with the study of interactions between humic acids as the main component of soil organic matter with a model organic pollutant presented by cationic surfactant Septonex (which was expected to interact positively with humic acids due to its charge) through unconventional combination of dialysis and diffusion techniques realized in diffusion cells together with isothermal titration calorimetry capable of elucidating the nature of ongoing reactions from a thermodynamic point of view. The experiments were performed with a humic acid isolated by standard isolation procedure from Leonardite (1S104H) purchased from the International Society for Humic Substances, with humic acids isolated from lignite as well as modal chernozem. The aim of the submited diploma thesis is to assess the influence of carboxyl functional groups in the structure of humic acids to interactions with Septonex. For this reason, said samples of humic acids have been modified by selective methylation of their carboxyl functional groups, which can no longer participate in interactions with ionic substances. Results from diffusion cells and isothermal titration calorimetry confirmed the assumption that Septonex interacted with all types of unmodified humic acids more than with their methylated derivatives. Despite the available literature, it was surprising that the differences in the interaction of humic acids with Septonex were not diametrically different when comparing unmodified humic acids with their methylated derivatives. The extent of these interactions was assessed through the apparent equilibrium constant Kapp determined in the diffusion (dialysis) experiments and from the course of enthalpy curves from isothermal titration calorimetry. After the experiments and their evaluation, it can be concluded that humic acids and Septonex in their interactions, due to their structures, probably apply not only electrostatic interactions, especially through available carboxyl functional groups of humic acids and positively charged hydrophilic parts of Septonex molecules, but also a significant role have a hydrophobic effect, hydrogen bonds and Van der Waals forces.
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Interaction of lichens and invertebrates with emphasis on mites
Vtípilová, Věra ; Steinová, Jana (advisor) ; Černajová, Ivana (referee)
Lichens interact with many groups of invertebrates. Acari (mites), Gastropoda (gastropods), Rotifera (rotifers), Nematoda (nematodes), Tardigrada (tardigrades), Protozoa (protists), Collembola (springtails) and Insecta (insects), especially Psocoptera (book and bark lice), Lepidoptera (butterflies and moths) and Coleoptera (beetles) represent the most common groups. These animals use lichens as a shelter and food. Lichens have different defence mechanisms, for example, secondary metabolites. On the other hand, invertebrates often mediate the dispersal of lichens. Some lichens can grow on shells or a body surface of living invertebrates. In my thesis, I describe individual groups of invertebrates that interact with lichens, and I mention specific examples of these interactions. A special emphasis is given on mites because they are one of the most important consumers of lichens, and I will pay attention to them in my diploma thesis.
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Food interactions of antibiotics
Nováková, Veronika ; Pourová, Jana (advisor) ; Carazo Fernández, Alejandro (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Veronika Nováková Supervisor: PharmDr. Jana Pourová, Ph.D. Title of diploma thesis: Food interactions of antibiotics Diploma thesis deals with clinically significant interactions between antibiotics and food. It defines basic concepts such as antibiotics, food, drug interactions and also drug-food interactions. The main part of the work deals with the characteristics of individual groups of antibiotics, describes their mechanism of action, including the antimicrobial spectrum, the main side effects and deals with the already mentioned interactions with food and beverages. St. John's wort, grapefruit, alcohol, or polyvalent ions in particular play an important role in these interactions, which can have a significant effect on the course of antibiotic therapy. The next part of this work deals with the effect of probiotics on the natural intestinal microflora, which is disrupted by antibiotics. The last part of the thesis deals with the issue of antibiotic resistance and the principles of correct and appropriate use of antibiotics, which have an impact not only on minimizing the emergence and development of bacterial resistance, but also help to prevent interactions, including drug-food...
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