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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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Reactions of spider and insect predators to aposematic prey
Koláčná, Klára ; Exnerová, Alice (advisor) ; Sentenská, Lenka (referee)
Aposematic prey advertises its unprofitability to predators by means of warning signals, which can be visual, chemical, acoustic or combined with each other as multimodal signals. Most experimental studies dealing with responses of predators to aposematic prey focus on vertebrates, especially birds. This thesis focuses on the most frequently tested groups of terrestrial arthropod predators - spiders, dragonflies, and mantises - supplemented by less tested insect predators. Most of the tested arthropod predators are able to learn to avoid noxious aposematic prey based on either visual, olfactory or acoustic signals depending on their perception. Some can remember this aversion for several days. Only in case of jumping spiders, ability to generalise previous experience with a particular prey to similar prey has been confirmed. Prey chemical defenses most often consist of cardenolides or aldehydes, which proved to be aversive for tested arthropod predators.
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Management generačních ryb candáta obecného (Sander lucioperca) a jeho vliv na produkci jiker a larev
MALINOVSKYI, Oleksandr
This thesis provides an improve to existing reproduction technics through investigation of ecology and physiology features of pikeperch broodstock: (I) Spawning behavior and selectivity to different types of spawning substrates as an important part of the biology of pikeperch species. The main output of the study was revealing of strong selectivity to the spawning site with neither water temperature nor availability of spawning places haven't affected substrate preference of pikeperch broodstock. (II) Spawning in captivity is leads to decrease in physiological status of the pikeperch broodstock, especially in females. It was found that one of the reasons of the decrease was male protective behavior, that in limited space of the reproduction unit is forwarded to female. Separation of the sexes significantly reduces number injuries and improved physiological status of the broodstock. (Ill) The study investigated efficiency of different antifungal agents for pikeperch broodstock. The long term exposure to salt bath in concentration of 2.5, 5 and 10 g L-1 and formaldehyde in concentration 0.015 ml L-1 were found to be highly effective and significantly decreased mortality after spawning. In addition, treatment with salt bath are environmentally friendly and recommended for practical use as an effective way to prevent mortality of pond-cultured pikeperch broodstock. (lV) The provision of live feed is crucially important for proper gametes maturation, particularly in pond-cultured fishes not accepting pellets. The study investigated the effect of temperature on daily biomass of prey consumed by pikeperch broodstock. Significantly increased prey consumption was found after temperature reached 4.5 °C. Females exhibited significantly higher prey consumption rate in compare to male. Study revealed the tendency for pikeperch to consume largest available prey after water temperature reached 8.5 °C.
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Antipredatory function of aggregations in aposematic prey
Mitlenerová, Barbora ; Exnerová, Alice (advisor) ; Pipek, Pavel (referee)
Aggregation is a very important strategy of many organisms. It occurs in both vertebrates and invertebrates. Besides other functions (foraging, thermoregulation, maintenance of humidity protection against dessication, epigamic, hibernation or aestivation), aggregation also carries out antipredatory function. Aggregation of animals may reduce the risk of attacks by predators and prey mortality. Reduction of the attack probability might be caused by the predator confusion effect, lower risk of prey detectability, dilution effect, more effective vigilance of aggregation members and increase of strength of the warning signal produced by aposematic prey. Experimental studies, focused on the role of aposematic coloration in antipredatory functions use usually birds as predators. There are many kinds of insects, such as true bugs or mealworms, or artificial prey used as a prey in the experiments. The combination of aposematic signals and gregariousness of prey might have a significant influence on both probability and frequency of predator attacks. The length of predator's hesitation before the attack and the attack intensity used on attack may differ according to the coloration and presentation (gregariousness) of the prey and therefore the chance of survival varies. Aggregation may also improve...
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Are body size and specific species colouration important cues for predator recognition by their potencial prey? Diplomová práce
Antonová, Kateřina ; Fuchs, Roman (advisor) ; Sedláček, Ondřej (referee)
I tested influence of a body size and overal colouration in feeders experiments on recognition of sparrowhawk (Accipiter nisus) by chosen species of passerine. Experiments were conducted in years 2015 ̶ 2018. I used a plush dummies which carried a specific featuress of raptor (hooked beak, claws) and specific features of genus Accipiter (yellow eyes, respectively yellow eyes and overal colouration). As a control, dummy of harmless pigeon was used. Smaller dummies (size of a great tit) were not recognized as a raptor regardless of colouration. Large dummies with colouration of great tit and pigeon were not recognized as a raptor as well. On a contrary, large dummy with colouration of robin was recognized as a raptor, respectively sparrowhawk. Most birds who were flying to the feeders, at first payed attention to global features (size, overal colouration). If these features belong to well-known harmless bird, then local features (particular) which characterize raptor or sparrowhawk had no effect. Birds did not pay attention to them. Therefore it depends on a context, in which potential local key features occure.
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Trophic ecology of the greater mouse-eared bat (Myotis myotis)
Bendová, Barbora ; Andreas, Michal (advisor) ; Bartonička, Tomáš (referee)
In 2012 it was observed foraging ecology of the three males of greater mouse-eared bat (Myotis myotis), inhabiting individual roosts in the interior of road bridge near Bernartice, and the nearest nursery colony of the same species in the village Senožaty (district Pelhřimov). In the period April to September in Senožaty were made 14 collections at intervals of approximately 14 days and in the bridge near Bernartice at similar intervals were made 8 collections from each male in the period from May to September. From each collection were subsequently been analyzed 20 samples (pellets) by the traditional method of preparation of faeces. Overall it was from all the bats analyzed 760 samples, of which 280 from the nursery colony and 480 from males. Based on the analysis was found diet composition of individual bats and of the colony, where the overall character of the trophic niche of the greater mouse-eared bat, seasonal dynamics in it's diet composition, sex differences and individual differences between males were observed. From a point of view of it's hunting strategy the greater mouse-eared bat showed itself as a ground gleaner, in whose diet were dominated larger Coleoptera, of which the predominant component were large, flightless, mostly forest Carabidae, adding medium and smaller species of...
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Crypsis on the principles of disruptive coloration
Kopčiková, Kristýna ; Kreisinger, Jakub (advisor) ; Pecháček, Pavel (referee)
The crypsis gives the oportunity to an animal to become inconspicuous in its natural environment to avoid being detected by potential observer (Cott, 1940, Edmunds 1974 Merilaita 2003). But crypsis isn't unambiguous term, there are few ways to achieve being cryptic and disruptive coloration and background-matching are one of them. The aim of this thesis is to summarize empirical evidence for the inmportace, the function and the expansion of disruptive coloration in nature. This research also constitutes a fundamental experiments testing the principles of disruptive patterns. It turns out that this coloration could bring for the bearer some selective advantages, but the experiments are too uniform and they have important methodological failures. Results of them are unclear so scientists have no consistent conclusions. The issue of disruptive coloration is very complicated and still poorly explored. There is need to invest a lot of more labor and study to be certain whether or how disruptive coloration works in nature. Powered by TCPDF (www.tcpdf.org)
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Owerview of snakes using strangulation to kill prey
Jeřábková, Adriana ; Vrabec, Vladimír (advisor) ; Killerová, Šárka (referee)
Purpose of studies was collecting list of snakes - constrictors. There were suggested two hypothesis; 1st - killing prey using strangling is mostly widen by large snakes than smaller ones. 2nd; Mechanism going while grabing and following killing of prey were in different kinds of snakes constrictors generated convergently and are similar. From given list of kinds of snakes and figures telling their proportions it is obvious that strangling as form of killing is major by snakes over 1,5m, therefore first hypothesis I can confirm so. Also from table of expansion individual genuses using strangling it is apparent that this method killing is known in all continents where snakes lives and simultaneously with fylogeneticaly receded kinds of snakes. I can then with higher probability confirm also second assumed hypothesis, nevertheless, own grabing and killing strategy of prey is different in some details. Some kinds challenge prey from ground, possibly from water, some kinds attack prey from trees and bushes. Difference in rotation of body along prey warries by grass snakes and by boid snakes. Boids bend neck verticaly around prey, while many grass snakes bend body sideways around the prey. It was made many tests of measuring strenght and mechanism strangling by various methods, e.g. Magnetic Resonance, Autopsy etc., however these experiments cannot be classified to this work for reasons of great amount given experiments and great amount of outcomes.
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Interactions between spiders (Araneae) and their prey
Nerpas, Marek ; Korenko, Stanislav (advisor) ; Kysilková, Kristýna (referee)
Spiders (Araneae) are predators utilizing many strategies for hunting their prey. Their diet is often extensive. To obtain food, many various interactions occur among the spiders, and some species are not even afraid to hunt over other spiders. In the first two chapters, I describe the environment of spiders. I focus on the basic classification of spiders, following by an overview of the most important families in Central Europe and their division into the weavers of different types of cobwebs, and spiders who do not hunt through the webs but have a similar style of hunting, in hunting groups (guilds). Further on, the work deals with intraspecific interactions between spiders, such as competition, cannibalism or cooperation that influence the success in hunting prey and consequently the success in survival of spiders. In the last two chapters I deal with the interactions in the framework of the hunting groups, and between different hunting groups that affect other species of the ecosystem and are a driving force in shaping animal communities.
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Phenotypic plasticity of planktonic rotifers as a response to predator.
VAJDIAKOVÁ, Nikola
The aim of this thesis is to assemble essential information about phenotypic plasticity of zooplankton, especially planktonic rotifers. More specifically, the thesis is focused on predatorinduced morphological changes. I introduced different types of predators and their behavioral, physiological and morphological impacts on zooplankton. Moreover, I examined the effects of inducible morphological defences on the planctic rotifers.
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