National Repository of Grey Literature 37 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Macroevolutionary and ecological implications of the theory of frozen plasticity
Toman, Jan ; Flegr, Jaroslav (advisor) ; Fatka, Oldřich (referee) ; Mikuláš, Radek (referee)
The frozen plasticity theory is a punctuationalist theory of adaptive evolution. It states that long periods of stasis, during which populations respond to selection pressures only by elastic change in the frequency of already present alleles, alternate in the evolution of sexual species with short periods of plastic evolution, during which alleles can get fixed or eliminated by directed selection. Asexual species are not expected to maintain such high genetic polymorphism in the long term. They should, however, be able to plastically respond to selection pressures throughout their whole existence. This difference between the evolutionary dynamics of sexual and asexual clades has a number of ecological and macroevolutionary implications. Concerning ecology, we could expect different environmental preferences of sexual and asexual species. Accordingly, in our first work that was based on a comparative study, we statistically significantly supported the hypothesis that (ancient) asexual groups of (eukaryotes) inhabit more stable and homogeneous habitats than their related sexual controls. Focusing on actually experienced, i.e. subjective, heterogeneity of the environment turned out to be the crucial factor of this type of research. From the viewpoint of macroevolutionary implications of the frozen...
Evaluation of rock masses (pebbles) on planets
Boldbaatar, Dayansetsen ; Kletetschka, Günther (advisor) ; Mikuláš, Radek (referee)
This research is science engineering topic based on compositional and volume information to figure out the mass of a rock pebbles on a planetary surface. For this purpose, 3D computing Photogrammetry method and X-ray Fluorescence methods were used to derive the necessity physical quantities for the mass computing First section discusses the moon, its characteristics and possibility of terraforming. The second half of this bachelor's thesis is focused on modeling and its techniques. The final part summarizes the results derived from modeling chapter.
Ichnology on crossroad: state of art of ichnofacies
Tisoň, Lukáš ; Mikuláš, Radek (advisor) ; Kadlecová, Eva (referee)
This bachelor thesis analyses the state of the current ichnofacies paradigm in detail. The introduction deals briefly with the origin and development of the ichnofacies concept in order to understand principles on which current paradigm is based. The thesis deals with the definition, purpose and interpretation of generaly accepted ichnofacies, offers their overview and points to problematic ichnofacies that do not strictly obey established rules. The meaning of the ichnofacial paradigm has been tested based on observations of trace fossils in modern settings. At the end of the thesis, the importance and functioning of ichnofacies has been evaluated and at the same time, solutions to the introduction of new ichnofacies has been presented. Key words: ichnofacies, trace fossils, ichnocoenoses, neoichnology
15th International Ichnofabric Workshop : program, abstracts, Field Guidebook
Kočová Veselská, Martina ; Adamovič, Jiří ; Kernhoff, M. ; Rifl, M. ; Šamánek, J. ; Mikuláš, Radek
Radek Mikuláš convened the 15th International Ichnofabric Workshop to Prague (April 27th – May 5th, 2019). Thirty-two specialists from over the world presented recent contributions from the mainstream branch of ichnology, e.g., ichnofabrics of terrestrial systems. Special discussion block was devoted to the use of computed tomography in the study of Ichnofabric. Three days (five days for participants of the post-workshop excursion) for the workshop were devoted to field excursions. Thereby, most of the localities known only through publications have been seen and evaluated directly to the world top ichnologists.
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Mineralogical forms, distribution and importance of freshwater ice
Vrbický, Tomáš ; Mikuláš, Radek (advisor) ; Pokorný, Richard (referee)
Ice is one of the fundamental components of the environment. It covers the land surface and significantly affects our lives both on a local and global level. It is the subject of considerable scientific interest, particularly in terms of its role in climate change - the ice is capable to release pollutants into the water environment or modify the composition of the atmosphere, represents a drinking water supply or "archive" of the natural environment. This thesis "Mineralogical forms, distribution and importance of freshwater ice" describes the most common forms of freshwater ice, its distribution and importance on the Earth surface and beyond. It introduces us to the issue of current direction of ice researching and approaches some open questions. Part of this work presents types of ice occurring in the Czech Republic.
Plant - insect interactions in lower Miocene of Central Europe: palaeoclimatological and palaeoecological implications
Knor, Stanislav ; Prokop, Jakub (advisor) ; Kvaček, Jiří (referee) ; Mikuláš, Radek (referee)
The paleoecology of plant - arthropod herbivory associations constitute very important source of knowledge about the phylogeny and co-evolution of both groups. The traces of herbivory interactions between plants and arthropods on the fossil leaves are preserved as so called damaged types (DTs) clustered into distinct functional feeding groups (FFGs). The diversity and frequency of these damage traces also seem to have been strongly influenced by environmental and climatic conditions. This research has been focused on rich fossil plant assemblages from the area of the Most Basin in the north-western Bohemia. The undergoing work has comprised the diagnosis of the individual damages on the basis of their specific morphological traits as their number, size, shape and distributional pattern on the leaf surface. The next issue has involved the statistical analyses concerning the differences in the frequency and diversity of the types of damage and functional feeding groups between two separate fossiliferous layers, namely those of the stratigraphically older Bílina Delta and younger Břešťany Clay. Significant differences were confirmed in this regard, especially in connection with achieved frequency and proportional occurrences of distinct functional feeding groups in the Bílina Delta. The galls were the...
Comprehensive study of the sandstone rock forms deterioration (Case study: Pravčická brána Arch, Bohemian Switzerland National Park)
Vařilová, Zuzana ; Přikryl, Richard (advisor) ; Vilímek, Vít (referee) ; Mikuláš, Radek (referee)
This PhD thesis contains the results of comprehensive research into the Pravčická brána Arch and surrounding sandstone massifs with focus on gaining more knowledge about natural dynamics and evolution of this rock formation, its current level of stability and the weathering processes it displays. Non-destructive methods were used for this comprehensive study; these ranged from detailed field documentation to monitoring temperature regime of the rock and included application of a geophysical survey and control monitoring of the course of arch body deformation. Laboratory testing was carried out for strength parameters and salt efflorescences together with weathered sandstones were analysed for chemical compounds. Main operating factors were monitored simultaneously, which particularly involved changes in external temperature, degree of sunlight and chemical composition of rainfall. Conventional as well as entirely new assessment procedures were used in synthesis and interpretation of the data collected, including knowledge of nonlinear dynamics of complex systems. The survey was designed to fully respect the protective conditions of the site, to make follow-up activities possible in future and to monitor any possible negative changes in the rock massif. The main results incorporate description of...

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