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I am here it is not
Daneková, Petra ; Hosnedlová, Klára (referee) ; Kohoutková, Karolína (advisor)
I have chosen the concept of mimicry, camouflage and disappearance because the subject of fusion and invisibility interests me. To vanish in the nature or in the city just with the help of body and clothes. For the purpose of this thesis I have created an outfit that will prove effectiveness of camouflage for the ordinary people watched by cameras everyday. By using this outfit I should find out whether digital devices are sophisticated enough to recognize a person even in the case that he has more legs or arms and his face is covered only with the eyes visible. In my thesis I am using several kinds of digital devices by which I am trying to figure out the effectiveness of created outfit. For comparation and better capture of person I have created two types of outfit. One of them is monochromatic while the second one, and more essential one, is printed with glitch. I am testing these two outfits both in exterior and interior. The outcome of the thesis are photographs and videos of person dressed in created outfits.
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Bird Appearances and Similarities
Figura, Roman ; Komárek, Stanislav (advisor) ; Daněk, Tomáš (referee) ; Jaroš, Filip (referee)
The presented work deals with a striking, yet usually neglected phenomenon by researchers, the similarity between the forms of different (closely unrelated) bird taxa. It mainly concerns visual signs of the body surface, the work also deals with other signs, including behavioral ones. The thesis demonstrates that these are not a few curious similarities, but a truly robust phenomenon, which apparently cannot be fully explained from a unifying point of view. Only some characters, which the work deals with, help their bearers to crypsis, aposematism or mimesis. In many other cases, their function is unknown. They can carry different functions in the life of their bearers, but it is often not possible to determine a single cause of their occurrence. In terms of the information contained, the work belongs to the largest works dealing with this topic known to the author.
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Výstražná signalizace barevných forem slunéčka východního (\kur{Harmonia axyridis})
BOROVIČKA, Martin
The efficiency of the aposematic defenses (colouration and chemical defence) used by three rare colour forms of Harmonia axyridis were tested using in the wild caught great tits (Parus major) as predators. I predicted that visually orienting predator will pay more attention to the rare colour forms, as they are not familiar with them and need to generalize the learned aversion to some other ladybirds to these novel ones.
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The occurrence and the function of eyespots in the vertebrate colouration
Helebrant, Václav ; Fuchs, Roman (advisor) ; Pipek, Pavel (referee)
Eyespots are a striking feature in the colouration of many animals. These are spots of a circular shape, which in their external appearance subjectively resemble the eyes of vertebrates. In invertebrates, they are found in insects, crustaceans and molluscs, while they are most widespread in butterflies. Within vertebrates, eyespots are most common in fish. Among amphibians, they are found in frogs, but their occurrence has not yet been mapped in detail. Eyespots occur rather rarely in reptiles and birds, and only remotely similar patterns can be found in mammals. Current research on the function of eyespots more or less reliably demonstrates that they play an important role in defense against predators or in communication within intraspecific interactions. The eyespots can fulfill the anti-predation function in two ways. According to the intimidation hypothesis, eyespots serve to prevent a predator from attacking. However, it is not yet entirely clear whether the spots frighten predators because of their similarity to the eyes of dangerous animals, or whether predators avoid the spots because of their conspicuousness and contrast with the surroundings. According to the deflection hypothesis, eyespots attract predators, but they direct the attack away from vital parts of the prey's body. In...
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Factors affecting behaviour of avian predators to hoverflies (Syrphidae) and their models (Aculeata)
Truhlářová, Marie ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
Batesian mimicry is an antipredator strategy used by harmless species to mimic dangerous models by their appearance. The so-called imperfect mimics are a phenomenon within Batesian mimicry. It would be expected that Batesian mimics are selected to resemble the model as perfectly as possible. However, in some species the resemblance is very poor. The aim of this study was to test reaction of predators towards a textbook example of Batesian mimics with imperfect mimicry, i.e., hoverflies (Syrphidae) and to verify some of the hypotheses describing imperfect mimicry. We conducted two experiments in which the model predators were great tits (Parus major). The topic of the first experiment was the effect of diversity of models on categorization and generalization of hoverflies. Birds were divided into two groups, with the first group receiving high diversity of models (10 species of Hymenoptera) and second group receiving low diversity of models (2 species of Hymenoptera). There were two parts of this experiment. Categorization training when great tits learn to discriminate between two categories of prey, palatable and unpalatable and generalization test, when great tits generalized their experience from categorization training to novel prey. Palatable prey was represented by non-mimetic flies (Diptera),...
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Does phylogenetic proximity positively correlates with the likelihood of an evolutionary origin of mimicry?
Kováčová, Katarína ; Kleisner, Karel (advisor) ; Raška, Jan (referee)
Mimicry represents a diverse group of similarities, which belongs to the phenomena of evolutionary biology. Even though mimicry is often interpreted as a convincing exam- ple of natural selection, it is necessary to consider the morphological and organizational processes that are responsible for the formation of organisms. In our work, we tested the hypothesis that mimicry occurs more frequently among insect genus that are phylogenet- ically closer than those that are phylogenetically more distant. To elaborate the work, we used 112 genus from the Insecta and Arachnida classes. The hypothesis was tested glob- ally, continentally and at the order level. Our hypothesis has not been refuted in Central and South America, Asia and Australia. At the order level, it was not contradicted in the order of Lepidoptera. We hypothesize that the explanation can be deduced from radical phenotypic changes that would ultimately disadvantage the given organism. 1
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Identity and Displacement in Contemporary Postcolonial Fiction
Olehlová, Markéta ; Nováková, Soňa (advisor) ; Franková, Milada (referee) ; Kolinská, Klára (referee)
English summary The main objective of this thesis is to present some key issues relevant for postcolonial field of study with respect to two basic areas of interest: concepts of identity and place, respectively displacement in contemporary postcolonial discourse and their reflection in fiction, too. The thesis should provide the potential reader with basic theoretical background based on the most fundamental sources and by means of selected literary works it should support (or disclaim, if necessary) conclusions reached by the most notable theories. This dissertation work consists of three major parts. In the introduction, apart from providing the motivational, theoretical and literary objectives of the thesis, I cover some basic difficulties that may occur when dealing with the postcolonial field of study. The central part of the thesis can be divided into two parts, each of them consisting of two further sections. The first one, "Identity in Postcolonial Discourse", is focused on one of the key terms in all of postcolonial theory: identity and other concepts related with it. I cover the basic development of theoretical reflection concerning this concept, drawing primarily from secondary sources dealing with it. The theoretical part on identity is succeeded by a chapter "Reflections of Identity in the...
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Spiders as senders and receivers of antipredatory warning signals
Raška, Jan ; Exnerová, Alice (advisor) ; Korenko, Stanislav (referee) ; Krištín, Anton (referee)
The introductory part of this thesis sums up the state of knowledge on aposematism and mimicry, the effect of aposematic and mimetic signals on spider predators, and cases when spiders do not receive but send such signals. Attachments of the thesis include four original manuscripts. In the first study, we presented jumping spiders (Evarcha arcuata, Salticidae) with different colour forms (red-and-black, yellow-and-black, white-and-black) of the firebug (Pyrrhocoris apterus, Pyrrhocoridae). Our goal was to compare reactions of the spiders to various intensity of aposematic signalization, expecting red-and-black coloration to have the strongest effect. Aversive learning of all colour forms was equally effective, but generalization of the learned avoidance to other colour forms was more effective after switch from less (white-and-black, yellow-and-black) to more (red-and-black) conspicuously coloured prey. When tested the next day, avoidance of the white-and-black prey got mostly forgotten. In the second study, we assessed little studied sensitivity of spiders to smells of unpalatable prey. After jumping spiders learned to avoid firebugs, most of them avoided the firebug smell, showing their sensitivity not only to optical, but also to chemical part of signalization of the unpalatable prey. In the...
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Mechanisms and effectiveness of antipredatory defences within red-and-black mimetic complex
Kotlíková, Lucie ; Exnerová, Alice (advisor) ; Baňař, Petr (referee)
Strikingly coloured species can form mimetic complexes. One of them is an extensive black-and-red mimetic complex in the Palearctic region. It consists of representatives across arthropod taxa with different levels of defense and investment in it. To describe individual mimetic relationships in this complex, it is necessary to know the effectiveness of these defense mechanisms against predators. Reactions of individual predators vary considerably. Differences in reactions primarily depend on the ability to perceive some components of defense, using sensory and cognitive abilities. Mechanisms and effectiveness of antipredatory defence are the subject of numerous studies, but there is still a lack of description of some mechanisms among many representatives forming this mimetic complex. For this reason, further studies are needed to allow the derivation of mimetic relationships prevailing in this mimetic complex in the future. Keywords: mimicry, aposematism, antipredatory defense, colouration, mimetic complex
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Spiders as senders and receivers of antipredatory warning signals
Raška, Jan
The introductory part of this thesis sums up the state of knowledge on aposematism and mimicry, the effect of aposematic and mimetic signals on spider predators, and cases when spiders do not receive but send such signals. Attachments of the thesis include four original manuscripts. In the first study, we presented jumping spiders (Evarcha arcuata, Salticidae) with different colour forms (red-and-black, yellow-and-black, white-and-black) of the firebug (Pyrrhocoris apterus, Pyrrhocoridae). Our goal was to compare reactions of the spiders to various intensity of aposematic signalization, expecting red-and-black coloration to have the strongest effect. Aversive learning of all colour forms was equally effective, but generalization of the learned avoidance to other colour forms was more effective after switch from less (white-and-black, yellow-and-black) to more (red-and-black) conspicuously coloured prey. When tested the next day, avoidance of the white-and-black prey got mostly forgotten. In the second study, we assessed little studied sensitivity of spiders to smells of unpalatable prey. After jumping spiders learned to avoid firebugs, most of them avoided the firebug smell, showing their sensitivity not only to optical, but also to chemical part of signalization of the unpalatable prey. In the...
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