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Diversity of Epilobium and methods to explore their hybridization
Kuchyňková, Lenka ; Kaplan, Zdeněk (advisor) ; Šemberová, Kristýna (referee)
Willowherbs (Epilobium) belong to the genera whose evolution is significantly affected by interspecific hybridization. Although this process often generates evolutionary novelties and leads to speciation, it can also result in genetic erosion and extinction. This thesis is mainly focused on the Czech Epilobium species that are potentially endangered by interspecific hybridization. The emphasis falls on the group of rare mountain willowherbs including E. nutans, E. alsinifolium and E. anagallidifolium. In addition to frequent interspecific hybridization, the research of this group is also complicated by the subtlety of distinguishing morphological features. The review also summarizes the available methods that can be used to study interspecific hybridization in the follow-up thesis.
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The Current Extinction of species
Schätz, Filip ; Storch, David (advisor) ; Hulva, Pavel (referee)
This bachelor thesis deals with the current process of species extinction. The main aim of the thesis is to answer the question how we can accurately describe this process. The understanding of this process is based on the limited sample of extinct species known to us, provided by the IUCN Red List. The sheer number of extinct species is affected by the use of different species concepts, the synonymy of binomial names and the difficulty of tracking individual extinction events. The Red List sample is subject to strong selection bias, so currently there are only reliable records of extinctions of groups of birds and mammals. These extinctions are mainly associated with their occurrence on islands. For other taxa, records of extinctions are sporadic, so the status of the current extinction process in these groups is unknown. It is not possible in most cases to relate to these groups the knowledge resulting from the study of different taxa. Estimates that attempt to describe the process beyond our knowledge also suffer from shortcomings. While the problems of expressing actual extinction rates stem from our ignorance of biodiversity, the inaccuracies of the SAR curve back-extrapolation method are mainly due to the attempt to generalise the overly complex effect of range loss on species numbers. The...
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Mountains as islands
Kačabová, Petra ; Storch, David (advisor) ; Ferenc, Michal (referee)
In this paper I deal with island biogeography and its applicability to isolated mountaintops, as an ecological equivalent of true islands. I discuss both true and mountain islands regarding their origin and the influence of long-term climate evolution on Earth. I underline some features of mountain islands, resulting from their topography and the dissimilarities of both types of island barriers. I find that mountain and true island communities might or might not have a number of species in a state of equilibrium, caused by balance between species immigration on island and their extinction. If the number of species on island is not in equilibrium, species extinction is not balanced by species immigration. I consider patterns of island communities, mainly nestedness, which has been frequently studied on mountain, as well as true islands. I discuss distribution patterns concerning invertebrates. And finally, I concentrate on recent methods of moutain island research and discuss mountain island isolation issues in terms of global warming.
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Limitation of species richness
Szostoková, Kateřina ; Storch, David (advisor) ; Šímová, Irena (referee)
Currently we can find two main hypotheses of diversity dynamics in time in literature - bounded and unbounded hypothesis. According to bounded hypothesis diversity is limited, while unbounded hypothesis says that there are no obvious limitations of diversity. Evidence for these main hypotheses comes mainly from paleontological research, studies of phylogeny and comparison of local and regional diversity. None of these approaches give us clear and incontrovertible evidence of diversity limits. The aim of this work is to show some evidence that confirm (or not) limitation of diversity in mentioned kinds of biological research. Also, I would like to point out some critics and imperfections of used methods.
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Vliv fragmentace a ztráty habitatu na primáty
Sniegon, Arthur F. ; Sedláček, Ondřej (advisor) ; Pluháček, Jan (referee)
Anthropogenic activities and human encroachment may cause profound and often irrevocable changes in an environment. This may result in challenges for most of the wildlife, including our closest extant relatives, non-human primates. Worldwide, primates may be particularly susceptible to human-induced habitat alterations owing to their large body size, social way of life, slow reproduction, large home-ranges, naturally low population densities and often strong dependence on forest cover. Three main phenomena have been described as major threats for primates: loss of the natural habitat and its conversion to human-dominated landscape, fragmentation of the remaining patches of suitable habitat, and commercial bushmeat hunting. Here I review the first two processes. If primates survive the initial disturbance, they are forced to adjust their demographic, behavioural and dietary traits. However, this may not be enough for their persistence in a long term as their genetic diversity might be compromised. Moreover, also parasitic infections may impact severely the disrupted populations. In this thesis, I reviewed the current knowledge in primates demography, population genetics, dietary changes and parasite interactions in altered habitats. Most of the studies examined the African continent and Latin America, a...
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Latitudinal gradient of biodiversity and its dependence on rate of ecological processes and evolutionary processes
Krupička, Jan ; Storch, David (advisor) ; Kubička, Lukáš (referee)
Unevenness in the distribution of species diversity on the surface of the earth is one of the most striking phenomena in ecology. Latitudinal gradient of biodiversity could be explained by different rates of evolutionary processes such as speciation and ecological processes that control the ratebof extinction. The goal is to collect and evaluate the literature on the temperature dependence or latitudinal trends in the rates of these processes. Matabolic theory of biodiversity serves as the best explanation of the rates of evolutinary processes and their dependance on temperatur, while an explanation of the rate of ecological process is lacking in empirical data and theories that would put them in relation to temperature and latitude. Explanation by More individual hypotheisis was proved unconvincing.
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Measurement of urine extinction in depending on ionizing radiation
RADOVÁ, Štěpánka
Urine Extinction Measurement in Dependence on Ionizing Radiation Dose Radiotherapeutic workplaces use ionizing radiation for treatment of tumorous but also some non-tumorous diseases. Medical staff of these departments is exposed to ionizing radiation on everyday basis and is thus endangered by harmful consequences. On the other hand a patient should be exposed to a neglect volume of ionizing radiation outside the radiated area. The conditions defining the means of protection for medical staff and patients are arranged by the law. So called dosimeters, are used for this purpose by medical staff, and urine might belong among them. This thesis deals with the issue whether urine could serve as a biological dosimeter that might be used either for continuous monitoring or for instantaneous determination of radiation dose. The next goal was to find out at what doses of ionizing radiation changes in urine extinction occur. The results show that urine provides qualitative but irreproducible values. Namely because of varying composition of urine and for presence of substances which, apart from water radiolysis, causing urine extinction changes, represent inhibitors or activators of these chemical reactions. This is why urine cannot serve as a biological dosimeter of radiation.
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