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Molecular aspects of interspecific hybridization of sturgeons related to polyploidy and in situ conservation
HAVELKA, Miloš
Sturgeons (Chondrostei: Acipenseriformes) display markedly disjunct distributions with a wide occurrence in the northern hemisphere. Their unique benthic specializations, conserved morphology, evolutionary age, the variation in their basic diadromous life history, and the large public interest due to their near extinction or critically endangered status make sturgeons and paddlefishes one of the most interesting group of vertebrates. In addition to that, ploidy diversity of Acipenseriformes possessing three ploidy groups having ~ 120 chromosomes, ~ 240 ? 270 chromosomes and ~ 360 chromosomes provides unique model for investigation of evolutionary processes which were going through the genome duplication events. Sturgeons are also notoriously known for their strong propensity to interspecific and intergeneric hybridization which can result in hybrids with various ploidy levels. All these facts make sturgeon genetics and cytogenetics a thriving but also complicated area for research. In the present work, the role of genome duplication and functional reduction evens in evolution of sturgeon species as well as sturgeons? ploidy levels and ploidy relationships among Acipenseriformes were investigated using molecular markers. In addition to that, clarification of origin of abnormal ploidy levels and observation of segregation pattern of microsatellite alleles in the course of hybridization of polyploid sturgeon species were included into this study. With regard to the all considerations and observations provided by this study we concluded that evolution of sturgeon species is still widely dynamic and ongoing process which might goes through the allopolyplodization as well as autopolyplidization events.
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Systematics and variation of Red Bartsia, Odontites vernus (Bellardi) Dumort. in the Czech Republic
BAĎUROVÁ, Tereza
The Master's thesis studied the Odontites vernus group in the Czech Republic. The group was presented by two different taxa based on the seasonal types and the ploidy levels: an early flowering tetraploid Odontites vernus subsp. vernus (2n = 4x = 40) and a late-flowering diploid Odontites vernus subsp. serotinus (2n = 2x = 18). Plants from 33 populations were sampled for measuring the ploidy level and 27 morphological characters for morphological analysis. Two ploidy levels were confirmed in the Czech Republic and a new late flowering tetraploid taxon (2n = 4x = 40) was found. The three taxa were separated from each other based on the seasonal variation, ploidy level, morphology and ecology.
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Phenotypic plasticity and cytotypes of \kur{Agrostis stolonifera} in the Czech Republic
KUBEŠOVÁ, Magdalena
Presence and range of phenotypic plasticity in the Agrostis stolonifera polyploid complex (Poaceae) was studied in the territory of the Czech Republic. Plants were cultivated under different experimental conditions. Stomatal size of different Agrostis stolonifera cytotypes was measured. Flow cytometry was applied for genome size estimation. Ploidy levels were determined for more than 150 samples of Agrostis stolonifera as well as several specimens of Agrostis canina, A. capillaris, A. gigantea, A. rupestris and A. vinealis. Absolute DNA content was estimated in all studied species. Isozyme analysis was used to test the possibility of the hybrid origin of pentaploid individuals of Agrostis stolonifera species.
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