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Species-specific and individual predictors of birds' collisions with glass obstacles in the Czech Republic
Semeráková, Anna ; Sedláček, Ondřej (advisor) ; Viktora, Lukáš (referee)
Recent landscape transformation is associated with the emergence of various artificial obstacles that change the natural form of habitats and biocorridors of free-ranging animals. Glass obstacles represent a particular problem due to their transparency and reflectivity. Collisions with glass represent one of the most significant causes of bird mortality worldwide, accounting for over hundreds of millions bird deaths annually. Many authors consider this source of mortality to be completely non-selective. In that case, total collisions mortality would represent a function of population size. However, here I assume that the relationship between collision mortality and population size is more complex and that certain avian ecological groups may be differently susceptible to glass collisions based on their specific ecological characteristics. Long-term records of bird-glass collisions in the Czech Republic were provided by the Czech faunistic databases. These records were compared with the population size of analysed species and with selected ecological and morphological species characteristics. Consistently with the premise, I found out that the greatest amount of collision mortality is explained by the species' population size. However, other species characteristics, such as higher body weight,...
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Intraspecific and intraclutch variability of avian egg
Králová, Barbora ; Jelínek, Václav (advisor) ; Sedláček, Ondřej (referee)
Egg-laying birds have a huge variation between species in terms of number, size, pigmentation, but also in the speckled nature of the eggs. Bird eggs vary not only between species, but also within species, even within a clutch. It is only recently that more speculation has begun about the possible causes of intraspecific variation. Hypotheses about intraclutch variation started to emerge even later. This thesis presents and describes some of the hypotheses dealing with egg variability. One of the most significant factors affecting intraspecific variability is food availability, which in turn affects female fitness. For intraclutch variability, most studies focus on the difference between the last egg and other eggs within the clutch. In many cases, the last egg has a size difference, but also a different amount of pigment compared to the other eggs in the clutch, which are not significantly different from each other.
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Temporal changes in bird communities at the landscape level in Třeboň basin
Havelka, Jan ; Sedláček, Ondřej (advisor) ; Reif, Jiří (referee)
Population trends of birds are usually studied mainly on large national and continental scales or, on the contrary, quite locally. In an attempt to link these spatial scales, we repeated a quantitative survey of bird communities in the Třeboň Protected Area twenty years later (between 2001 and 2021). Bird counts were conducted during the breeding season on a fifty- kilometre transect (128 count points) intersecting a diverse range of habitats. We found declines in long-distance migrants and insectivorous birds compared to more stable or slightly increasing populations of resident species. Consistent with known trends, we also observed declines in populations of species tied to agricultural landscapes. Deviations from the well described trends by JPSP and PECBMS relate more to individual species characteristics. For example, we observed increases in populations of otherwise declining House Sparrow (Passer domesticus) and Field Sparrow (Passer montanus), or nationally stable Eurasian Siskin (Spinus spinus). Using detailed mapping of habitat and vegetation changes and other ecological characteristics of individual species, we have attempted to explain these general and site-specific changes in bird abundance and population trends. We were also interested in the manifestations of the generally...
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Reasons for the global decline of insect populations
Váňová, Barbora ; Šípek, Petr (advisor) ; Sedláček, Ondřej (referee)
This thesis deals with the issue of global decline in insect populations. Insects are one of the most numerous and diversified groups of animals in the world. This community plays irreplaceable roles in nature, contributing to the proper functioning of the entire ecosystem. However, fairly compelling evidence has now begun to emerge of long-term insect declines around the world. These declines are caused by many causes and factors that contribute to varying degrees of decline in the abundance and diversity of insect populations, and are often interrelated. The aim of this thesis is therefore to provide an overview of this global problem, and in particular its main causes. The topic has been elaborated through the study of scientific literature and subsequent presentation of the impact of individual factors on specific insect species or groups. It was found that the main reasons for the decline of insect populations are the loss of natural habitats, pollution, the spread of invasive species and pathogens, climate crisis and light pollution. Keywords: insect decline, population, biodiversity, biomass, agriculture, land use, global change
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Factors threatening European raptors and actions for their conservation
Žandová, Denisa ; Reif, Jiří (advisor) ; Sedláček, Ondřej (referee)
Due to their visual appearance and general size, raptors are, among a general public, revered group of animals. This also, brings them more attention in sphere of animal conservation. Despite protection, which is given to them, raptors are among other birds severely endangered with their population decreasing in multiple places across Europe. The most frequent factors, which endenger raptors, are habitat loss, poaching, high-voltage powerlines, wind turbines and lead poisoning. This paper focuses on, describtion of methods of raptor protection, determination of efective protection measures, as well as determination of new useful solutions applicable for protection improvement. Studies has shown that in individual areas of Europe are endengering factors diferent than in others. Species with same ecological requirements and a way of life are endangered by same factors. The approach to these issues also changes depending on a country and some potential factors are not examined enough, yet. Thus it is of a great importance to spend more time on resolving these issues. Keywords: raptors, biodiversity conservation, risk factors, habitat loss, lead poisoning, poaching
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Pasture of horses as an essential tool in biodiversity conservation
Dudková, Andrea ; Malíček, Jiří (advisor) ; Sedláček, Ondřej (referee)
In recent decades, the approach of active management, preventing overgrowth and simplifying the species composition of non-forest biotopes, has dominated in nature conservation. Dominant plants, suppressing competitively weaker species, are therefore reduced for example by grazing of large herbivores. It turns out that horse grazing has considerable potential for enhancing biodiversity. The aim of this bachelor's thesis was to summarize the main aspects of horse grazing based on literature research and come to a prediction of its future use in nature conservation. Studies on the use of horse grazing in biodiversity conservation show that it works well to suppress competitively strong grasses and supports the presence of flowering dicots and associated insects. The disadvantage of grazing horses is that they do not consume woody plants and thus cannot suppress the growth of bushes. On larger areas (>20 ha), year-round wild horse grazing is used, while domestic horses are suitable for seasonal grazing on smaller sites. Due to the positive results of horse grazing in promoting biodiversity, the more successful suppression of competitively strong grasses compared to other herbivores and the lower level of human effort compared to mowing, it can be expected that cases of using horse grazing in nature...
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Synthesis and properties of biocompatible polyacrylamide-coated surfaces
Kopilec, Ondrej ; Sedláček, Ondřej (advisor) ; Studenovský, Martin (referee)
This bachelor thesis focuses first on the synthesis of N-substituted acrylamide monomers for the following controlled radical polymerization into corresponding polyacrylamides. The prepared library of 16 polymers differs in side-chain group structure and degrees of polymerization. The next part is focused on the characterization of polyacrylamides, using NMR, MALDI - TOF and GPC techniques. Polymers were then grafted to golden wafers and the properties of these surfaces were studied. Thickness and grafting density of layers were measured, via spectroscopic ellipsometry, and water contact angle goniometry was measured to characterize the surface hydrophilicity.
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Polymeric nanomaterials for targeted inhibition of tumor growth
Šťastná, Katarína ; Etrych, Tomáš (advisor) ; Sedláček, Ondřej (referee)
Galectins are carbohydrate binding lectins which possess many biological activities related to the development and progression of cancer. The purpose of this bachelor's thesis is synthesis, physico- chemical and in vitro preliminary biological evaluation of novel glycopolymers with high affinity to galectin-3. Several biocompatible water-soluble linear and diblock N-(2- hydroxypropyl)methacrylamide (HPMA) copolymers bearing multivalently presented glycomimetic ligands, were synthesized and characterized by number of analytical methods, i.e. GPC, UV-VIS spectrometry, DLS and NMR. The polymer carriers were synthesized by the controlled RAFT polymerization, their molecular weight ranged from 25,000-33,000 g/mol and showed quite low dispersity. Glycopolymers containing about 4 mol% of glycomimetic ligands showed high ability to inhibit apoptosis of T lymphocytes in vitro. Nevertheless, the hypothesis consisting in the improvement of biological activity due to the denser ligand presentation on diblock copolymers was not proved. The thesis concludes that the prepared glycopolymers, linear as well as diblocks, could hypothetically be convenient tools for synergic therapy with polymer drug delivery systems in cancer treatment. Keywords: polymers, HPMA copolymers, drug-free macromolecular therapeutics,...
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Long-term population trends in urban birds in Europe and Czechia
Grünwald, Jan ; Reif, Jiří (advisor) ; Sedláček, Ondřej (referee)
Urbanization ranks among the most important processes induced by the human civilization that affects ecological communities at the same time. Birds are the most frequently studied organisms in relation to urbanization. Different birds' species show different abilities to adapt to urban areas, so urbanization works as an environmental filter. As urban environment undergoes extraordinarily high rate of change, the characteristics of the environmental filter are changing rapidly, too. This could influence populations of urban bird species. We can expect that the population change of the species will be related to the time since urbanization; specifically, the early urban colonizers will decline due to alteration of urban environment, while the recent urban colonizers will increase. I obtained data on population trends from 2000 to 2016 for 95 common urban bird species in 16 European countries. Thanks to the cooperation with local expert ornithologists, I collected the data about the time since urbanization of these species in respective countries and I related these two variables filtering out the influence of 9 other species-specific ecological characteristics. Bird population trends had a statistically significant relation to the time since urbanization: the species that became urbanized earlier...
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Moths as nocturnal pollinators in the tropics
Barták, Michal ; Tropek, Robert (advisor) ; Sedláček, Ondřej (referee)
in English In this thesis, I reviewed the available knowledge on the role of moths in the pollination of flowering plants in tropical ecosystems. Moths appeared as relatively frequent visitors of flowers with moth-attracting adaptations. Moths were proved to be essential pollinators of some specialized plant species. An obligatory mutualism with micromoths was found in more than 550 highly specialized plant species. Macromoths appeared as effective pollinators of numerous tropical shrubs, trees, and herbs from numerous plant families. Moths were the only recorded visitors and/or pollinators in several cases. In communities, plant species with moth pollination syndromes were relatively uncommon, and moths were generally infrequent visitors of their flowers, which could also be affected by abiotic factors. The proportion of actually moth-pollinated plant species in communities was even slightly lower than the proportion of plants with moth pollination syndromes in other areas. Some moths (e.g., hawkmoths) can thieve nectar from virtually any shorter-spurred/tubed flowers with their long proboscis. Other moths were reported as nectar thieves in some too accessible flowers. However, moths were reported to be rare nectar thieves and prefer visiting the flowers they also pollinate. This thesis should...
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