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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Evolution and genomics of symbionts in Hippoboscidae

ŠOCHOVÁ, Eva January 2016 (has links)
Obligately blood-sucking parasites harbour symbiotic bacteria providing them B-vitamins and cofactors missing from their blood diet. Within Hippoboscoidea group (parasites of birds and mammals), tsetse flies as medically important vectors have been studied extensively while bat flies and louse flies tend to be neglected. This thesis is composed of two complementary manuscripts focused on phylogeny and origin of bacterial symbionts in Hippoboscidae family (manuscript 1) and their genome evolution (manuscript 2). First, phylogenetic approach was employed to determine lineages of obligate and facultative symbionts present in this group. Second, genomic and phylogenomic analyses were carried out to better understand evolution of obligate endosymbionts from the Arsenophonus genus in this group. Results of the two studies indicate that relationships between Hippoboscoidea and their symbionts are extremely dynamic with frequent replacements of obligate symbionts. This hypothesis is supported by both phylogenetic and genomic evidence, in particular, Arsenophonus endosymbionts of Hippoboscidae represent several distinct lineages (of likely different ages) with noticeable differences in genome features and metabolic capabilities. The data presented in this thesis thus greatly extend our knowledge about evolution and genomics of symbiotic bacteria in Hippoboscidae and bloodsucking hosts in general.
32

Evoluce hostitelské specializace blanokřídlých parazitoidů rodu Torymus / Evolution of parasitic Hymenoptera hosts specialisation of the genus Torymus

Bubeníková, Kristýna January 2018 (has links)
The genus Torymus (Chalcidoidea: Torymidae) has very diversified parasitic strategies and adaptations to its hosts. Its larvae are ectoparasitoids and attack mostly larvae of various gall wasps (Hymenoptera: Cynipidae) and gall midges (Diptera: Cecidomyiidae). However, few species prefer also other insect groups as a host or are even phytophagous. Many hypotheses concerning evolution of insect host associations were published, but have not been satisfactorily tested using parasitic insects as a model. In this thesis I studied coevolution of the genus Torymus and its hosts. The main questions are what kind of host shifts occurred during the evolution of host strategies and whether sister species of parasitoids are specific to the related hosts/or nonrelated hosts living in the same type of habitat. I also studied changes at morphological adaptations to its hosts. To test critically these hypotheses, I constructed phylogenetic tree of selected Torymus species based on 5 genes and compared their host association within and between clades of Torymus. Key words: Torymus, Chalcidoide, parasitoid, phylogeny, host specialisation
33

Molecular phylogeny and genome evolution of insect symbiotic bacteria / Molecular phylogeny and genome evolution of insect symbiotic bacteria

NOVÁKOVÁ, Eva January 2012 (has links)
Since the introduction of advanced molecular methods the research on insect bacterial symbioses underwent a major focus shift towards large scale phylogenetics and comparative genomics. These new fields provided answers to several fundamental questions of symbiont evolution, functional capabilities of the host-associated bacteria, and the role of symbionts in the host?s biology. However, the vast diversity and complexity of symbiotic relationships still leaves gaps in our understanding to a rich mosaic of various symbiont types, effects and transitions from facultative association to obligate mutualism. The presented study focuses on distribution, diversity, phylogenetic patterns, evolutionary transitions and genome evolution of two less known but ecologically diverse bacterial genera, Arsenophonus and Sodalis. The thesis also takes advantage of the knowledge on a well established symbiotic model between aphids and Buchnera and reveals several evolutionary patterns in the host and symbiont.
34

Skalimetrické znaky neotropických cichlid tribu Heroini: fylogenetické interpretace / Charakteristics of scales of neotropical cichlids (Tribus Heroini) - phylogenetic interpretation

STOPOVÁ, Barbora January 2012 (has links)
Work has the aim to describe charakteristics of scales selected species fish from the Central America and evaluace relationship with view on the group and compare scalimetric evolutional tree with molecular. Relationship between Heroini and Cichlasomatini is really close and Heroini constitute the second largest tribe of neotropical cichlids. These fish are very varied. Heroini is considered as monofyletic group. Development of the tribe in two branches. Theoretic part of this work is focused on phylogenetic knowledge from the other authors and group description. In the part with own issues there are characteristics of scales, microphotographs.
35

Nese zbarvení srsti evoluční informaci? / Could fur characters be a source of phylogenetic information?

VOLDŘICHOVÁ, Marie January 2011 (has links)
This work analysed phylogenetic utility of several characters associated with basic coloration, moulting and whorls in Cervidae via comparison of these traits with relatively robust phylogeny of this group based on several morphological, ethological and molecular data. I was able to detect probable evolutionary history of some selected traits, their ancestral state and synapomorphies of recognized clades.
36

Diverzita a biogeografie rodů \kur{Australoheros, Gymnogeophagus} a \kur{Crenicichla} (Perciformes: Cichlidae) v provincii Misiones, Argentina / Diversity and biogeography of the genera \kur{Australoheros, Gymnogeophagus} and \kur{Crenicichla} (Perciformes: Cichlidae) in the Province of Misiones, Argentina

PIÁLEK, Lubomír January 2009 (has links)
The diversity and biogeography of three dominant cichlid genera (Australoheros, Gymnogeophagus and Crenicichla) is reviewed within the Argentinean province of Misiones based on newly collected material specifically for this study. The results have revealed strikingly different structuring and origin of diversity between the three genera with implications for a future PhD study. The biogeographic implications of the reconstructed phylogenies using mitochondrial DNA have been compared with the geological history of the area revealing many new insights.
37

Meta-analysis of methodological artifacts of the phylogenetic imbalance. / Meta-analysis of methodological artifacts of the phylogenetic imbalance.

SMRČKOVÁ, Jana January 2011 (has links)
The influence of possible methodological artifacts (e.g. type of data or tree construction methods) on the tree topology was evaluated. A total of 413 phylogenetic trees was downloaded from the tree repository TreeBASE. Three indices of topology imbalance were employed, namely, Fusco & Cronk index, weighted average, and Colless index. The study reveals that methodological artifacts have probably a weak influence on the tree shape. Therefore, patterns in tree balance could reflect macroevolutionary processess, not a methodological bias.
38

Diverzita a fylogeneze archaméb / Diversity and phylogeny of Archamoebae

Zadrobílková, Eliška January 2016 (has links)
Members of the group Archamoebae are free-living or endobiotic amoeboid flagellates and amoebae. They live in anoxic or microoxic habitats, and their mitochondria have been reduced. They were originally thought to lack mitochondria and represent one of the earliest eukaryotes. However, this hypothesis has been refuted, and now it is evident that the Archamoebae belongs to the lineage Conosa within the supergroup Amoebozoa, together with aerobic slime molds (Macromycetozoa) and variosean amoebae and flagellates. Relatively simple microtubular cytoskeleton is a characteristic feature of Archamoebae. It consists of a single basal body from which a flagellum arises, lateral root, and microtubular cone. Cytoskeleton of aflagellated genera has been completely reduced. About 350 species names of Archamoebae have been created so far. However, most descriptions were based on inadequate morphological features. The identity of numerous species is uncertain, and many of them are likely synonymous. Another problem is a small amount of available molecular data. During our project, we have substantially improved the dataset of DNA sequences of archamoebae. On the basis of molecular and morphological data, we described 13 new species. We showed that genus Rhizomastix belongs to Archamoebae and displays a new type...
39

Genetická variabilita rodu Alburnoides v Ázerbájdžánu / Genetic variability of the genus Alburnoides in Azerbaijan

Omelchenko, Dmytro January 2016 (has links)
The Caucasus region is characterized by high rate of endemism and taxa richness of fishes. Azerbaijan is a country situated on the border between Europe and Asia with rivers flowing in the Caspian Sea. Natural environment of this country is represented by various habitats with diverse ichthyofauna. This region is very attractive for biogeographical studies because it lays on the border of two different ecoregions. Even on the modern stage of scientific cognition, there is still lack of data about freshwater fishes from that region. Spirlins or rifle-minnows (Alburnoides Jeitteles, 1861, Actinopterygii, Cyprinidae) is a genus of small freshwater fishes and it has been chosen as a focus of this thesis because of numerous reports of new species from surrounding countries. The presented thesis is one of the seldom molecular studies trying to reveal the taxonomical situation within the genus Alburnoides, describe the phylogenetic relationships between geographically isolated populations, and provide biogeographical implications for fishes in the Caspian Sea river basins. Both mitochondrial (cytochrome b, cytochrome oxidase subunit I) and nuclear (RAG1, rhodopsin) markers were used in the study and the Maximum Likelihood, Maximum Parsimony and Bayesian phylogenetic analyses were performed. Further, the...
40

Diverzita prasinofytních řas příbuzných plastidu euglen / Diversity of prasinophyte algae related to the euglenid plastid

Lukešová, Soňa January 2016 (has links)
Euglenophyceae represent a group of unicellular eukaryotic organisms that have gained during their evolution the ability to photosynthesize. They aquired plastids via secondary endosymbiosis with a green alga as the plastid donor. Phylogenetic studies searching for the origin of this organelle revealed the green alga Pyramimonas parkeae from Prasinophytes as the closest known relative to euglenid plastids. Pyramimonas parkeae and Euglena share several genes clusters with unique order of genes in their plastid genomes, which also point to the Pyramimonadales as the donor of the plastids. However, it is posible, that organisms more closely related to euglenid plastids than P. parkeae, occur in the environment. In my diploma thesis I focused on the exploration of diversity of Pyramimonadales and Euglenophyceae in environmental samples. I used several approaches to perform this task. I amplified parts of the plastid genomes in environmental samples by using specific PCR and determined their position in the phylogenetic tree. I also made large-scale phylogenetic analyses based on 16S rRNA and 18S rRNA sequences from representatives of the groups Euglenophyceae, Prasinophytes and environmental samples. The results revealed the presence of a large number of environmental sequences relative to the...

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