National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Allopatric evolution in rousettine fruit bats: from population and landscape genetics to phylogeography
Stříbná, Tereza ; Hulva, Pavel (advisor) ; Bryja, Josef (referee) ; Vallo, Peter (referee)
Population structure, biogeography and phylogenetic relationships of the fruit bat genus Rousettus have been studied in Africa and adjacent regions. The current population patterns of rousettine fruit bats in the Old World are influenced by several environmental attributes, namely the topography, climate and land cover. These variables are mirrored in fruit bat plesiomorphies related to the ecological niche of tropical flying frugivore, as well as apomorphies of rousettines including echolocation ability, roosting in caves and dispersal capacity in open landscapes with discontinuous tree cover. Phylogenetic relationships among species and subspecies of the genus have been indicated and confronted with the existing colonization scenarios. Insular populations (including habitat islands within desert oases) show frequent genetic differentiation from their mainland relatives suggesting successful founder events after traversing stretches of unsuitable habitats. Genetic differentiation evolving in less distant islands suggests involving behavioural mechanisms maintaining cohesion of isolated demes as site fidelity and natal habitat-biased dispersal. In sub-Saharan mainland Africa within the large range reaching from the southern border of Sahara to Cape Peninsula, Rousettus populations share a...
Genomic approaches for studying speciation
Vozárová, Zuzana ; Reifová, Radka (advisor) ; Hulva, Pavel (referee)
Technological advances in DNA sequencing along with the emergence of new informatics approaches have created new possibilities in many biological fields. In this bachelor thesis, I will focus on the informatics approaches used in speciation genomics, that is research field focused on the problematics of the origin of new species. I will introduce some statistical methods used by these approaches for parameter estimation. The four particular methods I will write about are Maximum likelihood estimation, Bayesian model, Markov chain Monte Carlo and Iterative approach. I will describe several methods used for the detection of interspecific hybrids and recent as well as historical interspecific gene flow. These methods include NewHybrids, the hybrid index, genomic and spatial clines and coalescent-based methods. The thesis demonstrates the usefulness of the connection of applied mathematics and genomics for addressing general biological issues, and speciation particularly.
Conservation genetics of grey wolf and snow leopard: effect of landscape attributes to the population structure
Benešová, Markéta ; Hulva, Pavel (advisor) ; Kreisinger, Jakub (referee)
Landscape genetic approaches allow to study effects of landscape to population microevolution. Landscape can influence gene flow even in large carnivores with good dispersal ability. Understanding the influence of landscape to the gene flow between populations is crucial for species conservation, especially in the species with low population densities. Aim of the study was to describe genetic structure of the grey wolf (Canis lupus) and snow leopard (Panthera uncia) in selected areas and to determine the influence of the landscape features on observed structure. Non-invasive genetic samples of snow leopard from Nepal were analysed, as well as invasive and non-invasive samples of grey wolf from Central Europe. Population structure was determined a posteriori using Bayesian clustering approaches that integrate genetic and geographical data, and compared to landscape connectivity models. Population structure of snow leopards is mostly influenced by human presence and presence of frequented roads, which represent a substantial dispersal barrier. Habitat suitable for this species is greatly restricted by altitude, however, during dispersal they are able to overcome areas with higher elevation than what is optimal for them. Pronounced genetic difference was found between central European and Carpathian...
Lineage distribution of the Gammarus fossarum species complex (Amphipoda) across Bohemian Massif and Western Carpathians
Rutová, Tereza ; Petrusek, Adam (advisor) ; Hulva, Pavel (referee)
Amphipods are an important component of temperate permanent freshwater macrozoobenthos. They have poor dispersal abilities, lack dormant stages, and their phylogeographies often reflect old historical processes. The genus Gammarus itself includes more than 200 described species spread in the Palearctic region. Many of the taxa previously described are, in fact, diversified species complexes, which is case of our most common Gammarus (G. fossarum). We have studied their diversity on the transect across the Bohemian Massif and the Western Carpathians, which form a significant biogeographical boundary for a number of other organisms. We tested whether the border between these areas is reflected in the phylogeography of G. fossarum as a representative of permanent aquatic fauna. Analysis of two mitochondrial markers revealed the presence of eight divergent G. fossarum lineages, which also differed in the nuclear genome. All eight lineages were found in the Western Carpathians, while the Czech Massif is inhabited only by two. The microendemic areas of some lineages and the occurrence of two apparently basal lineages of this complex, which were not found in southern regions, support the hypothesis that these amphipods survived Pleistocene glacial cycles even in West Carpathian refuges. We assume that...
Genetic variation and contact zone of two species of Slow Worm (Anguis fragilis, A. colchicapublics
Šifrová, Helena ; Gvoždík, Václav (advisor) ; Hulva, Pavel (referee)
The members of the genus Anguis are widely but hidden living reptile species in the Czech and Slovak Republic. Due to their slight morphological characters among species of the genus, presence of two out of five species in the study area has only recently been confirmed. However, a detailed knowledge about their distribution, contact zones or potential hybridization is still unknown or very insufficient. In this master thesis, 407 individuals of Anguis fragilis and A. colchica out of 281 locations were genotyped. 407 sequences of the mitochondrial marker ND2, 170 sequences of PRLR and 156 sequences RAG1 (both nuclear markers) were used for the genetic analyses. The results confirmed the dominant species A. fragilis for the Czech Republic and A. colchica for the Slovak Republic. The contact and potential hybrid zone has north-south direction from northern Moravia and Silesia, across the Morava River valleys to the Little Carpathians and the Danubian Lowland in Slovakia. The most important information of this thesis is about potential hybridization of these species. My analyses reveal that high number of individuals in the north-south direction zone has hybrid genotype. It allowed detecting the width of the hybrid zone and more accurate genetic structure among species and populations. In addition,...
Evolution of Olfaction in Mammals with Focus on Superorder Laurasiatheria
Vondráčková, Kamila ; Hulva, Pavel (advisor) ; Hanus, Robert (referee)
The evolution history of mammals is connected with the dominance of smell and olfactory communication, which are important sense and communication channels also in recent forms. Two systems are involved in detecting and processing the molecules of scent, the main and the accessory olfactory system. These systems distinguish different types of scents, odorants and pheromones, which are also detected by different types of receptors. Significant factors for comparison of the ability of smell between mammals are both the amount of olfactory genes and the size and complexity of olfactory structures. The main emphasis in this thesis is put on the sensory part of the olfactory system and hence there is effort to support characterization of particular taxa by genomic studies. The ability of smell, respectively amount and variation of olfactory gene repertoires has been formed during the evolution on different circumstances and the ecological adaptation played a great role. The amount and diversity of olfactory receptors vary a lot in mammals and range through anosmatic Cetaceans and microsmatic bats to macrosmatic carnivores. Present thesis is focused to the superorder Laurasiatheria because of its extensive ecological differentiation and diversification of smell abilities (from anosmatic to macrosmatic...
Abundance of and threats to the snow leopard in various regions of its occurrence
Valentová, Kamila ; Kindlmann, Pavel (advisor) ; Hulva, Pavel (referee)
Snow leopard (Panthera uncia) is an endangered species and its population size is steadily declining. This thesis attempts to introduce and analyse the main factors threating its survival with reference to each country of its occurrence: China, Bhutan, Nepal, Pakistan, Afghanistan, Tajikistan, Uzbekistan, Kyrgyzstan, Kazakhstan, Russia and Mongolia. To conserve the remaining snow leopard populations, it is necessary to detect its distribution in various areas. Here, recent data about its worldwide distribution are presented. Snow leopard has a very secretive lifestyle, which makes estimation of its abundance quite difficult. Therefore, I also present here an overview of methods, such as sign survey, capture-recapture, predator:prey biomass ratios, photo-capture rate and genetic analyses, used for estimation of abundance of snow leopard with reference to conducted studies. I discuss their advantages and disadvantages under different conditions. Key words: snow leopard, abundance, threats, worldwide distribution, conservation
Island evolution in bats
Holá, Barbora ; Hulva, Pavel (advisor) ; Bartonička, Tomáš (referee)
Order Chiroptera is the only mammalian taxon capable of powered flight. This key adaptation allows for high dispersion capabilities, therefore bats are often the only colonizers of remote islands. More than half of all bat species inhabit islands, and nearly a quarter of them are the islands' endemic organisms. They colonize islands around the entire world, being exempt from only very small, isolated or inhospitable islands.. Island biogeography has an extraordinary importance in many aspects of evolutionary and ecological disciplines. Because of its relative simplicity, as well as the impoverished nature of island biota, emerging interactions between island populations can be better observed compared to mainland. Species that might succumb to extinction due to competition on the mainland may survive on islands. Richness of island biota is subject to two opposing forces, colonization and extinction. A dynamic equilibrium occurs when the probability of colonization and extinction is equal, meaning the number of species is constant, but the composition of species may vary. Isolation, fragmented distribution, and the small size of island populations can lead to speciation, but can also conversely reduce genetic diversity, adaptive capabilities and ultimately cause extinction. The degree of isolation,...

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