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Physiological and hormonal mechanisms influencing ejaculate quality in birds
Mojžišová, Kateřina ; Tomášek, Oldřich (advisor) ; Svobodová, Jana (referee)
Sexual selection is an important mechanism of evolution. In addition to precopulatory sexual selection, arising when males compete for female partners, there is also postcopulatory sexual selection (sperm competition), when females copulate with more males. Even though most avian species are socially monogamous, most of them are also partially promiscuous. In such species, sperm competition is an important factor increasing variability in reproductive success between males. Male's success in sperm competition is primarily determined by sperm concentration, total sperm count and morphology and motility of spermatozoa. My bachelor thesis summarizes knowledge about the hormonal a physiological mechanisms that influence semen quality. This is especially the effect of sex and other hormones, physiological and oxidative stress, environmental conditions, antioxidant mechanism and composition of sperm cell membrane. Besides evaluating their influence on ejaculate quality on intraspecific level, I also describe their differences between avian species with respect to the differences of sperm competition.
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Crayfishes as a prey
MAN, Milan
Due to the increase in the number of non-native species of crayfishes and their presence on more and more localities, there is the possibility of their elimination using predatory fish species. The length relationships between a prey and a predator could clarify this possibility. The aim of this bachelor thesis was to develop high quality literary review about the incorporation of crayfish into the food chain and processing samples of a perch (Perca fluviatilis) from a locality with an occurrence of juvenile crayfishes (Astacus astacus). I wanted to verify the possibility of a perch predation on juvenile crayfish individuals. However, only three crayfishes were found in the analyzed perchs. After a very low percentage of crayfishes in the analyzed perchs, a laboratory experiment was carried out with young of the year of signal crayfish (Pacifastacus leniusculus) and perchs. Unfortunately, this experiment ended unexpectedly. The crayfishes were served to perchs, but the fishes showed no interest in them throughout the experiment. The results of food analysis show, that smaller perchs are able to eat crayfish, but they are not a sought-after component of their diet. In this case, the low frequency of crayfishes in the diet was caused by enough other food (insect larvae) and also the number of shelters in the pond, where the crayfishes were reared. In the experiment, I unfortunately failed to confirm the positive relationship between a perch as a predator and a juvenile crayfish as a prey. However, the conclusions of the other studies on the use of larger perchs show the preference and high frequency of occurence of juvenile crayfishes in their diet.
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Hatching synchrony in birds
Tippeltová, Zuzana ; Hořák, David (advisor) ; Riegert, Jan (referee)
This bachelor thesis is about hatching synchrony in birds. Generally, among birds there are two types of hatching - asynchronous and synchronous- and the type of hatching is primarily determined by the time of the onset of incubation. In many bird species, including most precocial ones, incubation does not begin until the last egg has been laid, which results in hatching of all the eggs within a few hours. In synchronously-hatched broods, all the chicks are about the same age. Thus no single individual has an advantage in size or strength over any of its siblings in the nest. The survival probability is then similar for all chicks which maximizes number of fledglings under favourable condition. In contrast many species of birds begin to incubate as soon as the first eggs is laid and hatch their eggs asynchronously over a period of days or weeks, handicapping last-hatched chicks with an age and size disadvantage. Many hypotheses have been proposed to explain why female birds start to incubate before clutch completion and some of those suggest that asynchronous hatching is a parental strategy for raising the largest number of offspring that food resources will allow when the abundance of food for the chicks cannot be predicted at the time that eggs are laid. The selective pressures leading to the evolution of...
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Productivity of environment and colouration of South African birds
Kubíková, Tereza ; Hořák, David (advisor) ; Albrecht, Tomáš (referee)
Understanding the relationships between species traits and the environment is essential for assessment of functional diversity. The variation in avian plumage colouration has attracted much scientific attention for a long time. It is thought that the colouration of birds is a product of interaction between environmental and sexual selection forces. Using two complementary three-matrix approaches (fourth-corner and RLQ analyses) I investigate geographical variation in plumage colouration of birds living along environmental gradient of productivity in South Africa. I suppose that productivity of environment could explain the part of variation in colouration of species at large geographical scales. I compiled information about 14 plumage traits for 649 species. Co- inertia analysis revealed that more vari-coloured species (e.g. with more saturated and vivid plumage), species with carotenoids in feather, blue-green or predominantly black species occur mainly in productive habitats such as moist savannas and woodlands in the north-east of the country. On the contrary pale species (e.g. greyishbrown), whose feathers are brighter (have higher values of brightness), occupy arid habitats in the west. It shows that another pattern such as iridescence, sexual dimorphism and brightness of particular body region exhibit...
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Abstract tasks in birds - spatial vs non-spatial tasks
Janská, Iveta ; Landová, Eva (advisor) ; Vlček, Kamil (referee)
The aim of this thesis is to compare spatial cognitive tasks (radial maze and analogs, geometry and features) and non-spatial abstract cognitive task (concept formation and categorization, transitive inference) in birds. Because each of tasks have different testing methods they are compared according to method types in separate thematic groups, which are discussed each other. The extension of this thesis on theories derived from human psychology such as self-recognition, episodic-like memory, and theory of mind.
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Success of reintroduction and supplementation programmes and behavioural changes in captive birds and primates.
Janovcová, Markéta ; Landová, Eva (advisor) ; Kůs, Evžen (referee)
The aims of this study are to: 1) review and evaluate the data available in scientific literature about reintroduction and supplementation programmes in birds and primates. The success of founder population reintroduction into the nature was assessed by its population size, survival rate and other life history traits. The breeding in captivity vs. using wild-caught animals for reintroduction and breeding conditions (longevity of captivity) would be checked. Breeding in enclosure versus semi-captive conditions was also checked. 2) mainly, assess behavioural and morphological changes of populations in relation with captive breeding in relation to success of reintroduction. 3) Map the geographic distribution of reintroduction programmes of particular higher taxa and evaluate the IUCN species status of animals used for conservation programmes.
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Function of antimicrobial proteins in albumen of precocial birds
Krkavcová, Eva ; Kreisinger, Jakub (advisor) ; Kratochvíl, Lukáš (referee)
Antimicrobial proteins contained in the albumen represent maternal effects, including the non- genetic component allocated into the egg during its oogenesis. Especially for species, whose broods are exposed to environmental influences until completation, these proteins play a crucial role in the viability of embryos due to their potential to influence the risk of microbial infection, which is considered one of the main causes of reduced hatchability. Also, it is assumed that these proteins, beacause of their specific traits, may influence phenotype of chicks, especially its size and immunity in the early postembryonal stage. In my thesis I focused on three antimicrobial proteins of avian egg white - avidin, lysozyme and ovotransferrin, which vary in their antimicrobial activity. For a better understanding of causal relationships between the concentrations of these proteins in the albumen and their effect on hatching success or offspring phenotype, a series of manipulation experiments and correlative measurements were performed. These experiments were held on the eggs of two precocial species - Japanese Quail (Coturnix japonica) and Mallard (Anas platyrhynchos). Our results indicate a crucial role of antimicrobial proteins in reducing the risk of bacterial infection and their natural concentration...
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Interspecific hybridization in birds: lessons for conservation
Štěpánková, Klára ; Reif, Jiří (advisor) ; Vokurková, Jana (referee)
Interspecific hybridization is quite common in recent years. Favorable factors are rarity of a species, limited time for partner selection, misdirected preference in mating partner selection of females, preference for males with more pronounced sexually selected traits, greater body size and habitat destruction. Factors which lead to the artificially interspecific hybridization due to habitat destruction include deforestation, fragmentation of the territory, urbanization, abandoning agricultural areas, as well as translocation of species into the regions where they did not originally occur. These species can later interbreed with the native species and if the latter are rare and the former aggressive, it can result in increased threat potentially leading to extinction of indigenous populations. Exceptionally, interbreeding can lead to the emergence of a new species; however, this type of origination of a new species is not common in animals. Hybridization is a natural phenomenon important for the evolution. Nevertheless, anthropogenically induced or assisted hybridization represents a serious problem for the species conservation. Finding a solution to overcome the negative impacts of such interspecific hybridization is difficult and there is no exact and universally applied methodology to date. Key...
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The role of ultraviolet light in communication of birds
Šulc, Michal ; Sedláček, Ondřej (advisor) ; Albrecht, Tomáš (referee)
Recently, it has been found that the visual system of birds and humans differ remarkably, especially in the ability to perceive ultraviolet radiation. This component of the spectrum significantly affects various types of the birds' behaviour. UV reflection may be an indicator of the qualities of males, i.e. females often prefer individuals with expressive UV ornamentation. Likewise, parents can distribute the delivered food unevenly among their nestlings, depending on the nestlings' reflection of ultraviolet radiation. Recent studies also showed that the hosts of brood parasites may use UV spectrum as a key for recognizing the parasitic eggs from their own. The aim of my bachelor thesis is to review the current knowledge of the influence of UV radiation on sexual selection of birds, the interaction between parents and offspring and interactions between brood parasites and their hosts.
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The effect of climate change and land use change on the long-term population trends of birds in the Czech Republic
Koschová, Michaela ; Reif, Jiří (advisor) ; Voříšek, Petr (referee)
There are number of future projections of species' geographic ranges developed under conditions of ongoing climate change. However, only a few studies have assessed what are the characteristics of species explaining interspecific variability in the projected range shifts. Examination of such relationships is important for development of effective conservation strategies mitigating the effects of climatic changes. For this purpose, I calculated the predicted shifts of European ranges in Czech birds based on maps in A Climatic Atlas of European Breeding Birds and explored relationships between these predicted shifts and several ecological traits. We found significant effects of the type of European distribution and habitat requirements. Concerning the type of European distribution, the largest shift is predicted in the central species and the northern species compared to widespread and southern species. According to the habitat type, the largest shift showed forest birds in contrast to the urban species which will shift slightly. The former pattern is probably attributable to spatial constrains different among these specific groups (central species are less limited compared to widespread species). The latter pattern could be explained by higher sensitivity of forest species to climatic changes...
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