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Food composition and feeding selectivity of zooplankton
Lis, Jonáš ; Škaloud, Pavel (advisor) ; Čablová, Radka (referee)
Zooplankton are an important link in the food web between phytoplankton and higher tro- phic levels, and understanding their feeding preferences is the key to unraveling the functions and dynamics of aquatic ecosystems. Current knowledge of zooplankton food composition is limited, consisting mainly of laboratory experiments that have revealed different hunting strategies and selection of prey based on size and nutritional value. Recently, publications have emerged that, through the use of DNA metabarcoding, provide a completely new and comprehensive insight into the diversity of zooplankton diet composition, especially copepods, cladocerans and rotifers. These methods reveal that the feeding niches of copepods and cladocerans are distinct and do not overlap. In general, both groups are said to prefer mainly diatoms as their food, when available. The food niches of rotifers are so diverse that no clear trend can be established for the entire phylum. Cyanobacteria appear to be the main source of energy for zooplankton and are proba- bly consumed by metazooplankton largely as secondary prey when consuming ciliates and other heterotrophic prey. Furthermore, differences in feeding niches between species are known and can be partly explained by their vertical distribution, and different levels of feeding...
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Vliv typu ustájení na reakci koní na nový předmět
ČERNÁ, Michaela
Horses are highly sensitive animals that react intensely to new objects or environments that are unfamiliar to them. This rapid response stems from their natural role as prey in the wild, which is why they have instinctive fright reactions. The aim of this thesis was to develop a methodology for testing horses' reactions to new objects based on available literature and to evaluate the influence of factors such as type of housing and the age of the horses. The testing included 18 horses aged between 1 and 22 years from three types of housing (active stable, box housing, and pasture housing). Fear tests lasting 5 minutes monitored reactions to objects such as colored ribbons and a blue tarp. The mattress crossing test lasted a maximum of 10 minutes. In both fear tests with colored ribbons and the tarp, horses from box housing showed greater signs of nervousness. Statistically, they spent more time moving compared to horses from the active stable (an average of 10,5 seconds more for colored ribbons and 4,8 seconds more for the tarp). Conversely, individuals from active stables consistently spent more time exploring (an average of 17 seconds more for colored ribbons and 25 seconds more for the tarp). In the fear test of mattress crossing, no difference was demonstrated between the horses from the observed types of housing (p-value = 0,679 > 0,05). A correlation analysis assessed the influence of age on the duration of various behavioral displays when encountering a new object. In the case of the tarp and colored ribbons test, older horses spent less time standing, exploring, galloping, and inside the designated circle compared to younger individuals. Conversely, older horses walked more and spent more time on the tarp and eating compared to younger ones. Older horses needed more time to overcome the mattress compared to younger ones (r = 0,12). The significance of the enriched environment, presented in this work by the active stable, is in the milder reaction of horses to new objects and the reduced risk during human contact.
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Aktivita raka mramorovaného v závislosti na reprodukčním cyklu
MARKOVÁ, Kateřina
The aim of this thesis was to elaborate a literature review on the topic of crayfish activity, in particular their feeding activity and the use of shelters, including an emphasis on the role of sex and the reproductive cycle. I also focused on the characteristics of the marbled crayfish, Procambarus virginalis Lyko, 2017 and its usability as a model organism. The experimental part of the thesis focused on comparing three groups of female marbled crayfish (with ovulum, with glair glands and without ovulum). Experiments have been carried out using a method for ecological assessment of feeding behavior and predator-prey relationship in various prey densities in the form of larvae of buzzer midge Chironomus plumosus (Linnaeus, 1758) by functional response analysis and subsequently tested for the effect of shelter presence at uniform prey densities levels. In our experiment, all three groups of tested females showed a type II functional response typical of predators. The results indicate that females without ovulum have been the most active in terms of food collection in all cases, with a generally positive effect of the presence of shelter. Females with employed ovulum are generally less active in terms of consumption, processing and overall aktivity due to hormonal, physiological and consequently behavioural changes. Females with glair glands behaved similarly to females with ovulum in our experiments, being more cautious and less active than females without ovulum. This was probably due to their increased gonadosomatic index (GSI) and, conversely, their decreased hepatopankreas to total body weight ratio, which renders these females unable to physiologically ingest large amounts of submitted food. Female GSI decreases again after ovulation, nevertheless, even females with already employed ovulum did not consume more food, as females prefer safety at this stage of the reproductive cycle. They are less active, move more slowly, spend more time in a shelter, tend to their eggs, and thus cannot devote themselves fully to hunting and prey processing. Regarding its life strategy, the marbled crayfish is a generally suitable model organism for use in various areas of research, however, it is important to take into account its rapid life and reproductive cycle and adapt the conditions of the given experiments to this fact, as the parallel use of female marbled crayfish at various stages of the reproductive cycle can modulate results in terms of their activity. Certain differences in the presented results may also be due to the origin of the experimental animals, as with very few exceptions all performed experiments with marbled crayfish have been carried out using laboratory individuals. A number of conditions that change seasonally in nature have been kept constant in the laboratory. Therefore, it is important to keep in mind that in wild, crayfish are also exposed to both biotic (predation pressure of various species of fish, birds or mammals) and abiotic (changes in temperature and water chemistry) factors that can influence food activity. Nevertheless, we assume that the patterns observed here will also be valid for female crayfish living in the wild nature. However, the lack of similar experiments leading to the elucidation of female activity depending on the stage of the reproductive cycle provides a room to investigate other, not just crayfish species.
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Reactions of avian predators to automimicry in milkweed bugs (Heteroptera: Lygaeidae):
Stránská, Anna ; Exnerová, Alice (advisor) ; Baňař, Petr (referee)
Automimicry, or intraspecific variation in defence mechanisms in aposematic prey, is very common in nature. Especially in chemically protected prey. This study contains two experiments. The first experiment investigated the reaction of naive predators, which were Great tits (Parus major), to automimetic prey. The prey was the black-and-red-bug (Lygaeus equestris). The tits were divided into three experimental groups and each group was presented with three bugs that were fed on an artificial diet with different amounts of cardenolides. The control group was presented with prey that had no cardenolides in the diet. The group tested with the low concentration received bugs that fed on a diet with a low concentration of cardenolides and the group tested with the high concentration received bugs that fed on a diet with a high concentration of cardenolides. In a generalization test, all groups were then offered a single firebug (Pyrrhocoris apterus). It was found that the group tested with the high concentration experienced a higher rate of aversive learning. This group also killed and consumed fewer firebugs than the other two groups. The group tested with high concentration generalized most to novel red-and-black prey because they were least likely to attack the firebug. The second experiment tested...
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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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Vliv intenzity managementu umělé obnovy dubových porostů na interakci mezi pavouky a jejich kořistí
Kárych, Jan
The aim of the research was to determine the effects of intensive management carried out by milling and full-scale treatment and extensive management during the preparation and care of artificially regenerated oak stands on the trophic networks of web spiders and their prey, which are sensitive to changes in the vegetation cover and canopy structure or openness. The procedure for evaluating the results was divided into two parts. Food webs were investigated in the field by collecting spiders and their webs with prey in plots during a total of two collections in June and August of 2021. Subsequently, from the collected samples, individual representatives of spiders were determined at the level of species or genera. The prey of spiders was determined at the level of orders or suborders. The obtained data were processed using statistical methods and evaluated. The results show that the amount of data was not optimal, but it confirmed the assumption that the total numbers of spiders and their prey were significantly higher on unmilled areas, as well as the species diversity, than on milled areas.
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Reactions of predators towards species of red-and-black mimetic complex
Kotlíková, Lucie ; Exnerová, Alice (advisor) ; Baňař, Petr (referee)
The red-black mimetic complex in the Western Palaearctic region includes a large number of arthropod species. These species differ in the degree of their mimetic resemblance, as well as in defensive mechanisms and their effectiveness against various predators. This study is based on two experiments. The first experiment was carried out with adult great tits (Parus major) and artificial prey (photographs). The birds were divided into two experimental groups and were trained to discriminate between palatable and unpalatable prey. One group was trained with higher diversity in the coloration of unpalatable prey (ten species of subfamily Lygaeinae), while the other was trained with low diversity in the coloration of palatable prey (ten individuals of the same species, Lygaeus equestris). After ten learning blocks, two generalization blocks followed, in which both groups received the same prey that was completely different from the prey during learning phase. The rate of learning was not significantly different between the two groups. However, more effective generalization was observed in the group trained with higher prey diversity. However, this trend was only observed in the first generalization block. On the second day, both groups achieved similar generalization success. The second experiment was...
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Molecular interaction of developing axons with the surface ectoderm
Matějček, Miroslav ; Machoň, Ondřej (advisor) ; Rozbeský, Daniel (referee)
The complex of cranial nerves consists of twelve pairs of nerves, which connect organs of the head with the central nervous system. One of the organs, which are innervated by cranial nerves are whiskers (also known as vibrissae). Whiskers are special type of mammalian hairs, which are innervated by the infraorbital branch of trigeminal nerve. These hairs provide information necessary for orientation in terrain, localisation of prey and locomotion. The potential role of axons in whiskers development has been discussed for many years. However, this hypothesis has not yet been confirmed. In this research we have used murine strains Neurog1 KO and Meis2 cKO with either abnormal or completely missing trigeminal nerve. Thanks to the analysis of embryonic development in these strains we have denied our hypothesis, that axons of trigeminal nerve serve a role in initiation of whisker follicles. In Meis2 cKO embryos we observed malfunction in formation of whisker follicles. The expression of Meis2 during the development of whiskers has an influence on various signalling cascades including Fgf, Shh and Bmp. In regards to changes in mentioned signalling cascades we suggest that the whisker follicle development is altered between the first dermal and first epidermal signal.
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Evolution and function of hidden anti-predator signals
Ziková, Magdaléna ; Exnerová, Alice (advisor) ; Pipek, Pavel (referee)
Hidden anti-predator signals (HAS) are hidden colour patterns in an otherwise cryptic prey; they are revealed upon encountering a predator. HAS include deimatic signals (DS) and flash signals (FS). DS are used when at risk of predation, typically after being discovered by a predator. Their position in the predation sequence (PS) differs by species. DS are often linked with deimatic behaviour, that boosts their efficiency. The use of DS in later stages of the PS occurs more often in defended prey, which may thus speed up predators' avoidance learning. In undefended prey, DS may trigger startle or fear responses, confusion or sensory overload in the predator, thereby pausing or stopping the attack. FS are exposed during the prey's escape, usually early in the PS before a predator detects the prey. This can cause a predator to form a wrong impression of the prey's appearance, making it harder to find. FS can also attract the predator's attention during pursuit, thus decreasing its chance of noticing an evasive manoeuvre. Dynamic FS, in which different colours alternate during movement, can make it hard to estimate the prey's position. The presence of both types of HAS is often linked with prey body size. The efficiency of FS is affected by the flight initiation distance. The efficiency of DS is related to...
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The Library of the Capuchin Monastery in Olomouc as Part of the Swedish Book Booty
Růžičková, Lucie ; Veselá, Lenka (advisor) ; Marek, Jindřich (referee)
The diploma thesis maps the fate of the library of the Capuchin Monastery in Olomouc. It focuses on the period of occupation by Swedish troops between 1642 and 1650 and the Swedish book booty. One hundred preserved titles, which are registered in the database The Swedish Booty of Books from Bohemia and Moravia 1646-1648, are then analysed. Historical circumstances that are connected to the Capuchins' arrival in Bohemia and Moravia are described in the first part. The origin of the Capuchin Monastery and library in Olomouc is clarified. Subsequently, significant moments of the Swedish occupation of Olomouc are presented, especially with regard to the Capuchin convent. At the end of the first part, there is a description of the process and circumstances of the Swedish confiscation of the library and its following transportation. In the second part, the preserved books are characterized. They are labelled according to their age, linguistic characteristics, origin and outer form. A content structure as well as preserved provenance are examined. This characterises the Capuchin library and its administration. In conclusion, the new knowledge of the history of the Capuchin library and its collection before the Swedish confiscation in 1645 is introduced.
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