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Morphological versus molecular delimitation of the genus Pleurothallis R.Br. (Orchidaceae)
Baláž, Přemysl ; Chumová, Zuzana (advisor) ; Figura, Tomáš (referee)
Pleurothallis R. Br is a genus of Neotropical orchids and one of many genera of a subtribe Pleurothallidinae. The genus Pleurothallis has undergone a very complex nomenclatural and taxonomic improvement over the last century, which is the main topic this thesis focuses on. Based on available literature, it compares two generic concepts of the genus Pleurothallis, a former morphological concept and a molecular concept, which reflects evolutionary history. The morphologically conceived Pleurothallis included (as of 1999) over 1500 more or less similar species divided into nearly 40 subgenera and over 20 subsections, sections and series. Some of the subgenera of morphologically conceived Pleurothallis have been raised to a generic level (e.g. Acianthera or Specklinia), others were merged with other already existent genera of Pleurothallidinae (such as Stelis). In some cases both generic concepts agree on which species they include; a genus Acianthera contains most of the species included in morphologically conceived Pleurothallis subgenus Acianthera. From the point of view of evolution, however, both genera are only distantly related. Much more frequent case is disagreement between both generic concepts, the most striking example can be seen when morphologically conceived Pleurothallis subgenus...
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The relationship between genetic and ploidy variation in the context of differing ecological conditions of two species of the genus Pteronia (Asteraceae) in the Cape
Havlíčková, Eliška ; Chumová, Zuzana (advisor) ; Záveská, Eliška (referee)
The genus Pteronia is an example of a recently radiated and taxonomically complicated genus of the family Asteraceae (sunflower family) with endemic connection to southern Africa. Most of the species are associated with the Cape region, an area characterised by a Mediterranean type of climate, which is comparable in species richness to the flora of tropical areas, especially on smaller geographical scales. The factors behind the high diversity of the Cape are environmental heterogeneity, climatic stability (low extinction and accumulation of species) and regular disturbance by fire. Polyploidization, one of the main mechanisms of plant evolution, has been an overlooked and denied phenomenon in the Cape for a long time. Individual cases of polyploidy are being revealed, but the causes of their emergence and extent of their occurrence are unknown. The presented work focuses on polyploidization in the genus Pteronia from the perspective of two species with different ecological valence. On the widespread to invasive species Pteronia incana and, on the contrary, on the endemic species of succulent karoo and deserts, Pteronia glabrata. Using flow cytometry, genome size variation was investigated and ploidy levels determined. The obtained cytometric data were used to compare climatic, topographic,...
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Chumová, Zuzana (referee)
Genus Sorbus is a very complex group of vascular plants. Various genetic lineages which can be fixed by apomixis are driven by interspecific hybridisation and polyploidy. Species from S. aria agg. have the highest variation probably due to an extra mechanism - introgressive hybridisation. There are several concepts of the aggregate which are usually based on three main species: S. aria, S. umbellatta and S. graeca. Therefore, new microspecies are derived by genome doubling and hybridisation between the main species. Units of the aggregate are assessed differently as the distinction of taxa is very complicated due to the overlap of the morphological variability. The aggregate itself can be sometimes considered as a category for species of uncertain origin or identification. Four species from S. aria agg. occur in the Czech Republic. In addition, the conclusion offers questions that will be addressed in the master's thesis.
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Causes of diversity in the Cape Floristic Region
Havlíčková, Eliška ; Chumová, Zuzana (advisor) ; Záveská, Eliška (referee)
The Cape Floristic Region (Capensis) is the smallest phytogeographical kingdom in the world with an area about 90,000 kmš (or 190,000 kmš if the succulent karoo is included). However, thanks to the subtropical climate influenced by the cold Benguel current and the isolated location behind the ridges of the Cape Mountains, it is characterized by an extremely diverse flora. There are about 11,000 species of plants, of which 79% are endemic. The Cape region shares many characteristics with other Mediterranean areas, but in many ways it is a unique environment. In this bachelor's thesis, the Cape flora is set in a global context and compared with other Mediterranean areas. Geological development, floristic and vegetation composition are described. The work also contains summarised information about the possible causes of high plant diversity and endemism of the Cape region. Keywords: Cape Floristic Region, Mediterranean, plant diversity, polyploidy, South Africa
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Sources of variation in the genus Anthoxanthum L.
Chumová, Zuzana ; Trávníček, Pavel (advisor) ; Mano Loureiro, Joao Carlos (referee) ; Kopecký, David (referee)
The genus Anthoxanthum (sweet vernal grass, Poaceae) represents a taxo- nomically intricate polyploid complex with a large phenotypic variation and still poorly resolved evolutionary relationships. The thesis deals with Anthoxanthum sect. Anthoxanthum in Europe, which comprises five traditionally recognized perennials (A. odoratum, diploid and tetraploid A. alpinum, A. maderense and A. amarum) and three annuals (A. gracile, A. aristatum and A. ovatum). Combination of different methods (DNA flow cytometry, sequencing of nrDNA ITS and two plastid regions, fluorescence and genomic in situ hybridization, climatic niche characterization and spatio-temporal modelling) was used to investigate ploidy and genome size variation of the genus across its European range, and to clarify the species origin and phylogeny of its members. Eight taxonomic groups that predominantly corresponded to traditionally recognized species were delimited on the basis of genome size values and phenotypic variation. While our data supported the merger of A. aristatum and A. ovatum, eastern Mediterranean populations traditionally referred to as diploid A. odoratum were shown to be cytologically distinct and may represent a new taxon. Genuine intraspecific variation in genome size was detected within the genus and the evidence for...
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Sources of variation in the genus Anthoxanthum L.
Chumová, Zuzana ; Trávníček, Pavel (advisor) ; Mano Loureiro, Joao Carlos (referee) ; Kopecký, David (referee)
The genus Anthoxanthum (sweet vernal grass, Poaceae) represents a taxo- nomically intricate polyploid complex with a large phenotypic variation and still poorly resolved evolutionary relationships. The thesis deals with Anthoxanthum sect. Anthoxanthum in Europe, which comprises five traditionally recognized perennials (A. odoratum, diploid and tetraploid A. alpinum, A. maderense and A. amarum) and three annuals (A. gracile, A. aristatum and A. ovatum). Combination of different methods (DNA flow cytometry, sequencing of nrDNA ITS and two plastid regions, fluorescence and genomic in situ hybridization, climatic niche characterization and spatio-temporal modelling) was used to investigate ploidy and genome size variation of the genus across its European range, and to clarify the species origin and phylogeny of its members. Eight taxonomic groups that predominantly corresponded to traditionally recognized species were delimited on the basis of genome size values and phenotypic variation. While our data supported the merger of A. aristatum and A. ovatum, eastern Mediterranean populations traditionally referred to as diploid A. odoratum were shown to be cytologically distinct and may represent a new taxon. Genuine intraspecific variation in genome size was detected within the genus and the evidence for...
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Chumová, Zuzana (referee)
Genus Sorbus is a very complex group of vascular plants. Various genetic lineages which can be fixed by apomixis are driven by interspecific hybridisation and polyploidy. Species from S. aria agg. have the highest variation probably due to an extra mechanism - introgressive hybridisation. There are several concepts of the aggregate which are usually based on three main species: S. aria, S. umbellatta and S. graeca. Therefore, new microspecies are derived by genome doubling and hybridisation between the main species. Units of the aggregate are assessed differently as the distinction of taxa is very complicated due to the overlap of the morphological variability. The aggregate itself can be sometimes considered as a category for species of uncertain origin or identification. Four species from S. aria agg. occur in the Czech Republic. In addition, the conclusion offers questions that will be addressed in the master's thesis.
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