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Can birds manipulate sex ratio of their offspring?
Tomiška, Lubomír ; Kratochvíl, Lukáš (advisor) ; Fuchs, Roman (referee)
The aim of this study is a summary of existing knowledge about skewed sex ratio in birds. This controversial topic represents one of the most important questions of evolutionary ecology. We still miss consistence in finding ultimate causes just as proximate mechanisms although there was an expansion of experimental studies already in the last decade of the 20th century which was caused by an invention of the new technology in sex determination. On the other hand, there are many convincing proofs of skewed primary, secondary, tertiary and even quartenary sex ratio so the facultative manipulation or obligatory sex ratio bias is presumable. My Bachelor's thesis compares studies focused on the similar ultimate causes and tries to point out their deficiencies together with contributions to research of this topic. Observation of sex ratio includes many specifics which are mentioned in theoretical introduction. The second part offers potencial proximate mechanisms which could be responsible for sex ratio manipulation. Within the analysis of studies I found sex ratio manipulation of the first egg in clutch as common trend which could fit to selective ovum resorption as a proximate mechanism.
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Changes in expression of immune-related genes after induction of inflammation in birds
Pojezdná, Anežka ; Vinkler, Michal (advisor) ; Chudíčková, Milada (referee)
Inflammation is one of the most important immunological mechanisms that protect animals from diseases. In my thesis I summarized information on changes in gene expression in tissues in the course of the inflammatory immune response in birds. I tried to describe the main features of the immune response in birds and highlight the differences to other vertebrates, especially mammals. I focused mainly on the surface molecules of various types of immune cells, as well as on signalling by soluble factors called cytokines. Although in general features are the inflammatory reactions in birds and mammals similar, in my thesis I have shown that a large portion of mediators and signalling molecules work very differently in these two vertebrate groups (e. g. the TNF SF-mediated pro-inflammatory signalling) and that substantial variation many be found even between different species of birds. Powered by TCPDF (www.tcpdf.org)
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Altitudinal migrations in animals and their study methods
Zenklová, Tereza ; Sedláček, Ondřej (advisor) ; Klvaňa, Petr (referee)
Migration as a response to the seasonality of the environment is common in many animal taxa. Strong fluctuation of the climate is usually connected to regions in the temperate zone, quite common is in the tropical regions as well. Typically, it is even more pronounced in high altitudes. In such environment, many animals could migrate altitudinaly as a response to changes in the climatic conditions or food abundance. But determinants of altitudinal and long-distance latitudinal migrations could be different. The objective of this work is to determine factors influencing altitudinal migrations in diverse taxa (particularly in birds and bats) and in different biogeographical regions. I am trying to find some common features of migrating species, such as diet or temperature and rain tolerance. Especially tropical species are partial migrants, which means that only some individuals of the population migrate. I will discuss common features of such migrating infividuals. Study methods of altitudinal migration will be a part of this research as well. The work will be primarily concentrated on tropical regions.
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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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