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Non-fish prey in the diet of fish-eating mammals, Eurasian otter (Lutra lutra) and mink (Neovison vison)
Tuzarová, Veronika ; Čech, Martin (advisor) ; Poledníková, Kateřina (referee)
The Eurasian otter (Lutra lutra) is considered, along with the American mink (Neovison vison), a significant fish predator not only in the Czech Republic but also in other regions across Europe. One of the goals of this study is to determine, based on available literature, the types of prey that form the diet of the Eurasian otter and the American mink, specifically focusing on the non-fish component of their food and how the percentage representation of these items changes in the diet of both species depending on habitat and season. Another objective is to verify whether the American mink has a higher proportion of non-fish prey in its diet compared to the Eurasian otter. The processed data describing the diet through spraint analysis in biomass units were divided according to climatic regions, i.e., temperate, Mediterranean, and also based on the type of aquatic environment, i.e., stagnant or flowing water. The results of the study indicate that the American mink consumed, on average, three times more non-fish prey (74 % biomass) throughout the year than the Eurasian otter (24 % biomass). The seasonal variation had the most notable impact on the consumption rate of frogs and birds in the non-fish diet of both predators. According to the analyzed data, both predators especially focused on frogs,...
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Specific response of primates to snake predators
Regásková, Kristýna ; Landová, Eva (advisor) ; Lhota, Stanislav (referee)
The specific response to snake predators in primates is due to long coevolution with snakes. This long coevolution has led to a specific and complex response in primates when confronted with snakes. The cues by which primates recognize snakes versus other types of stimuli may be based on olfactory or visual information. Reactions such as a priori fear or avoidance may be followed by various antipredatory responses such as specific vocalizations, avoidance behaviour, early escape or, conversely, active defence and mobbing. The response to venomous snakes and constrictors can vary in many ways based on the different threat they pose. Key words: Predation, mobbing, snake, primates, vocalization, anxiety
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Diptera in food webs of wetland ecosystems
Pijálková, Helena ; Hadrava, Jiří (advisor) ; Kolář, Vojtěch (referee)
Families of the order Diptera are frequently found in freshwater wetlands, affecting nearly all trophic levels, serving as detritivores, herbivores and predators. Diptera are characterised by an enormous ecological variability of their larval life strategies, which often differ even within individual families. Their adults form an important connection between the aquatic environment of a wetland with its terrestrial surroundings. As a result, adults of various wetland Diptera may serve as pollinators, predators and a prey of other animals including humans. Until now, research of food webs in wetland ecosystems has been focused mainly on a few economically significant groups of Diptera such as mosquitoes, or has been focused on the role of Diptera in transfer of heavy metal from wetlands to other ecosystems. However, overall wetland dipteran diversity still remains understudied. Examining the roles of insects as well as other organisms in food webs is important for example to simulate possible consequences of introduction or extinction of certain species on ecosystems. Further research is therefore necessary to understand how do various dipteran taxa affect other organisms in wetlands as well as their surroundings. Keywords: Diptera, wetlands, ecological webs, detritivory, herbivory, predation
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The effect of amoeba predation on the evolution of virulence in human pathogenic microorganisms
Drncová, Eliška ; Šuťák, Róbert (advisor) ; Konupková, Anežka (referee)
Amoebae act as one of the main regulators of microbial communities, where, as a result of their predation, selection pressure is exerted for the emergence of defence mechanisms to achieve resistance. This adaptation allows microorganisms to randomly infect the human body and successfully defend against components of innate immunity, especially macrophages, which, like amoebae, are phagocytic cells. The manifestation of virulence in opportunistic pathogens is due to conserved macrophage pathways used for degradation of ingested material, which the microorganism has already encountered in amoebae. Because of this similarity, amoebae can be used to investigate the interaction between a pathogen and its host, which includes research on the virulence mechanisms of many human microbial infections. Among the most extensively studied organisms whose pathogenicity results from long-term interaction with amoebae are the bacterium Legionella pneumophila and the microscopic fungus Cryptococcus neoformans, with very different virulence strategies and manifestations. Understanding the evolutionary context and the advantages that microorganisms gain during interaction with amoebae informs us about the origins of virulence of opportunistic human pathogens.
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Faktory ovlivňující početnost nepůvodního savčího predátora kočky domácí (Felis catus) ve středoevropské kulturní krajině a lidských sídlech.
KALENDOVÁ, Pavlína
The domestic cat is currently one of the most widespread invasive predators, which causes great losses to populations of many species. Due to its strong association with humans, individuals of this species are found on almost every continent and many islands, where it acts as a strong extinction factor. Using point counts, I surveyed the abundance of cats and bird species in the vicinity of České Budějovice and evaluated whether selected environmental factors influence the presence of domestic cats. The selected factors included site type, habitat, weather, temperature, season, and amount of vegetation at the site at the time of the inspection. The weather was only factor that had a statistically significant effect. Specifically, more cats were recorded on partly cloudy and sunny days than on bright or gloomy days. I also investigated whether the presence of the domestic cat at a given location has an effect on the number of recorded bird species or the number of individuals. According to the results, the presence of one or more cats at particular sites did not have a statistically significant effect on the number of bird species or the number of individuals.
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Domestic cats (\kur{Felis catus}) as a phenomenon in the conservation biology - their impacts on biodiversity
NOVOTNÁ, Nikola
Lately, a negative impact of ferocious domestic cats on environmental diversity has been ascertained. Using questionnaires, long term observations of cat prey (prey they brought home) and using database data (NDOP, rescue stations and ringing stations) we were finding out about the composition of cat prey throughout the year in the Czech Republic. Based on the questionnaire results, cats bring home 5x more mammals than birds. Out of the results of a long-term cat prey observation it turns out that cat prey consisted of, out of 93% mammals, 6% birds and out of 1% reptiles and insects. In the first observed season (winter), an average of 1 cat brought a 0.02 prey per day, in the second season (summer) 0.21 prey per day, and in the third season (autumn) 0.38 prey per day. Out of the obtained information it turns out that the cat´s impact on environmental diversity is greatest during the third observed season, and is the lowest during the first observed season. The mammal hunted for most frequently was a vole, while the bird hunted for most frequently was a sparrow. Based on our results, birds were carried home most frequently during the summer season, while mammals were carried home most frequently during both the summer and autumn seasons, which was caused by the fact that mostly all kinds of animals were mating during this time. For cats, it is then relatively easy to catch inexperienced young individuals. Out of all the hunted prey, 2.6% consisted of animals being officially protected in the Czech Republic. Thus, the cat´s impact on protected animals in the Czech Republic was proven.
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Interactions between plants, herbivorous insect and predators: mechanisms and ecological importance
MRÁZOVÁ, Anna
The thesis describes the interactions between the three trophic levels from different perspectives. It focuses on the role of plants, herbivorous insect, and invertebrate predators and birds in trophic interactions. More specifically, it describes indirectly induced plant defence and communication with higher taxa and changes in predation pressure and insect communities in response to defensive chemical compounds released from herbivory-damaged plants.
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Role of habitat complexity and predation in the structuring of aquatic communities
SOUKUP, Pavel
This thesis focuses on the roles habitat complexity and predation play in the structuring of aquatic communities. Chapter one provides an overview of the way habitat complexity structures communities separately, and by altering predator prey interactions in all aquatic habitats. The following two chapters examine their combined effects using different predator-prey pairs and time scopes: short-term laboratory experiments and a medium-term mesocosm experiment.
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