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Ontogenetic changes in antipredator defence strategies
Schusterová, Zoe ; Exnerová, Alice (advisor) ; Šípek, Petr (referee)
Changes in antipredatory strategies are a timely topic because they help us understand the benefits and limitations of each strategy. They can also help explain certain behaviors of animals at a given ontogenetic stage. My thesis summarizes the existing knowledge on this phenomenon. The first chapter provides an overview of taxa in which the change of antipredatory strategy during ontogeny has been described. I then focus on the antipredatory mechanisms subject to change. I then present hypotheses explaining the origin of antipredatory strategy change and the benefits it confers on animals. Finally, factors that may influence strategy change are discussed. Keywords: antipredatory strategy, predation, aposematism, crypsis, mimicry
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Biogeography of the herpetofauna of the Aegean Islands
Sýkorová, Marta ; Šmíd, Jiří (advisor) ; Papežík, Petr (referee)
In the last thirty years, the biogeography of the herpetofauna of the Aegean Sea has been the subject of thorough research. In evolutionary biology, islands are considered to be model ecosystems. Morphological, physiological and behavioral changes in some species can be observed on them. These changes are described as so-called "island syndromes". The occurrence of these syndromes depends on the size of the island, its distance from the mainland and the age of the island as well as on population density, availability of resources and presence of predators. The specific manifestations of these syndromes in reptiles of the Aegean islands are: the occurrence of endemism, gigantism and dwarfism, color changes, more frequent tail autotomy, cannibalism and food specialization. Most of these changes are described in lizards of the Podarcis genus, especially on Podarcis erhardii, as it is the most widespread reptile in this area. The second very widespread and therefore often researched reptile is Mediodactylus kotschyi. Changes often take place on small islands, so individuals tend to be compared with members of the same species from a larger island or mainland. The number of endemic species is significantly higher on islands that are longer separated from the mainland. The existence of gigantism and...
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Aquatic insects versus fish: adaptations to fish predation
Chawner, Adam Mark ; Černý, Martin (advisor) ; Jor, Tomáš (referee)
in English In this thesis, I review how aquatic insects have adapted to fish predation in various habitats during all phases of their life cycles. Aquatic insects are a large group of heterogeneous species and this review introduces these orders and species, including the environments they inhabit. Fish are some of the most common and most impactful predators of aquatic insects and this thesis identifies a wide range of behavioural, morphological, chemical and life history defence mechanisms of various complexity and uniqueness aquatic insect orders have developed to counter fish predation. Most aquatic insects are subject to predation during their aquatic larval stage. A few orders also inhabit the water as adults, as is the case most notably for aquatic Coleoptera. More complex adaptations to fish predation are presented in this order. Oviposition is noted as a strategy used to negate fish predation even before individuals hatch. The use of fish predation as means to control mosquito larvae communities is presented and reviewed. Keywords: aquatic insects, fish predation, defence mechanisms, adaptation to predation
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Influence of the intensity of begging on the rate of predation in the common sandpiper and common cuckoo
ČAPEK, Jan
In this research, I examined whether the louder calls of the common cuckoo (Cuculus canorus), a nest parasite, would increase the rate of predation on the nest of the red-backed shrike (Lanius collurio), whose nestlings call at a lower volume. The experiment was conducted during both the nesting season of the red-backed shrike, primarily in June, and in the autumn of 2023. During the spring trials, nests were situated within bushes, whereas in the autumn trials, they were positioned on the ground. Each experiment involved three nests, each subjected to a distinct audio recording: one featuring the vocalizations of a young common cuckoo, another with those of nestlings of the red-backed shrike, and a third serving as a silent control. Predation rates were assessed across these nests to determine whether certain recordings elicited higher predation rates compared to others.
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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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Interactions among free-living prokaryotes and protists in microbial communities
Jirouchová, Kateřina ; Pánek, Tomáš (advisor) ; Fiala, Ivan (referee)
Protists and prokaryotes live in the natural environment in complex microbial communities whose members interact with each other. These communities consist of a few to many species that interact with each other in many ways such as predation/prey, ecto/endosymbiosis, parasitism, modulation of development or behaviour and harmful algicidal/bactericidal interactions, resulting in a complex network of interactions that influence structure of the microbial community as well as metabolism and behaviour of present species. This bachelor thesis is an overview of the interactions between free-living protists and prokaryotes within microbial communities, excluding well-studied interactions such as predation, parasitism, and ecto/endosymbiosis, while focusing on the diversity of lesser- known interactions, highlighting their importance and future research opportunities.
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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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Synurbanization in wood pigeon (Columba palumbus) and Eurasian magpie (Pica pica)
Tesařík, Jáchym ; Lučan, Radek (advisor) ; Hořák, David (referee)
Both Eurasian magpie and Wood pigeon are typical synanthropic bird species. By studying the available sources, I found that during their synurbanisation, both species have undergone several changes that have facilitated their transition from rural to urban habitats. Due to their adaptability, they have no problems colonizing urban environment and have managed to occupy new and diverse range of nest sites. Thanks to synurbanisation, both Magpie and Wood Pigeon have been able to expand their range and increase their overall abundance. Possibly the biggest threat to urban populations of both species is nest predation, which locally leads to declining population trends and reduced breeding success. Because of predation pressure and the adaptability of both species, I think we can expect not only an increase in abundance and population density in their urban population in the future, but also the occupation of new and more diverse nesting habitats in closer proximity to human settlements.
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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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