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Genomic and Cellular Integration in the Tripartite Nested Mealybug Symbiosis
HUSNÍK, Filip
The PhD thesis is composed of three publications on genomic, metabolic, and cellular integration between the host and its symbionts in the tripartite nested mealybug system. The articles revealed a path to an intimate endosymbiosis that can be compared to what we think happened before (and to some extent after) bacterial ancestors of key eukaryotic organelles, mitochondria and plastids, became highly integrated into their host cells. I argue that these much younger symbioses may tell us something about how the mitochondria and plastids came to be, at the very least by revealing what types of evolutionary events are possible as stable intracellular relationships proceed along the path of integration.
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Evolutionary origins of intracellular symbionts in arthropods
HUSNÍK, Filip
Intracellular symbionts are widespread among arthropods, particularly within insects. Obligate symbiotic associations are known to have originated multiple times between the arthropods feeding on nutrient-poor diets and bacteria from various groups. However, exact phylogenetic positions and relationships among these symbiotic lineages are mostly unclear or vague. This thesis consists of an exemplary case study on the most symbiont-rich bacterial group, Enterobacteriaceae, already published in BMC Biology. It uses advanced phylogenetic tools and extended taxonomic sample to establish phylogenetic relationships among individual symbiotic lineages and their phylogenetic affinity to freeliving relatives. To provide it with broader background, the publication is accompanied by a review on general evolutionary forces influencing origin and maintenance of intracellular symbiosis in arthropods. Apart from overviewing the current known diversity of the symbiotic bacteria, it also points out specific drawbacks in inferring symbionts phylogeny and consequences that can phylogeny have on our understanding of intracellular symbiosis.
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Molecular phylogeny of intracellular symbiotic Gammaproteobacteria in insects
HUSNÍK, Filip
Many groups of insects harbor mutualistic intracellular bacteria. These bacteria originated mainly from two bacterial phyla: Bacteroidetes and Proteobacteria. The thesis is focused on phylogeny of Enterobacteriaceae - the most diverse group of endosymbiotic bacteria within Gammaproteobacteria. The study brings new phylogenetical data on "primary" symbionts and summarizes the current state of knowledge on their phylogeny, evolution and diversity.
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RSS.