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Watermilfoils (Myriophyllum) in the central Europe
Hrdinová, Magdalena ; Trávníček, Pavel (advisor) ; Prančl, Jan (referee)
Genus Myriophyllum L. (watermilfoil) belongs to one of the most species-rich genera within Haloragaceae (Saxifragales). It includes three invasive species, which are of major concern - European M. spicatum L., North American M. heterophyllum MICHX. and South American M. aquaticum (VELL.) VERDC. All of them occur in Central Europe as well as native M. verticillatum L. and M. alterniflorum DC. lacking more significant invasive growth up to now. It is not only its invasivness that makes genus Myriophyllum so fascinating. It also displays extremely high phenotypic plasticity which is accompanied by determination difficulties. Moreover, recent research indicates that Myriophyllum tends to hybridize producing more invasive hybrids than parental taxa. Such traits pose a formidable challenge to scientists to deal with possible future invasive growth of non-indigenous Myriophyllum species in Central Europe. Therefore, thorough study of factors influencing evolution success of plants should be conducted. One of the key factors seems to be polyploidy. Research into polyploidy offers a new approach to watermilfoil issues. Additionally, according to preparatory study all native Central European Myriophyllum species can be easily distinguished by flow cytometry. That enables to study polyploidy in an...
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Conservation aspects of endemism in Central Europe with special respect to genus Sorbus
Tesařová, Anna ; Urfus, Tomáš (advisor) ; Macková, Lenka (referee)
Endemit is an organism living exclusively within a particular area on Earth. There are several mutually interconnected mechanisms leading to endemism i.e. allopathic speciation, polyploidization, hybridization and apomixis. This thesis deals with describing particular modes of endemic speciation and their occurrence. The most significant concept is certainly discrimination of paleoendemites and neoendemites. Paleoendemites are very rare and within Central Europe occur scarcerly only in Western Carpathians. Neoendemites are hardly comparable among Central European states. The concentration of endemics is closely related to the global centers of diversity that are distributed in highly unbalanced way. The genus Sorbus is essential group with regard to endemism in Central Europe. That is why the experimental part of my thesis was focused on flowcytometric analyses (absolute genome size and DNA ploidy level) of 13 endemic Sorbus species. Triploidy was proved to be prevailing ploidy level. Among triploid samples 6% of variation was recorded. The absolute genome size of the remaining endemic taxa indicated tetraploid level.
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Variation of the species Urtica dioica in Central Europe
Rejlová, Ludmila ; Urfus, Tomáš (advisor) ; Mandák, Bohumil (referee)
Although the European flora belongs to the best explored at the global scale, still there are several largely neglected plant groups, which may surprise by marked variation. One of these groups is Urtica dioica s. l., consisting of vaguely described taxa (microspecies / subspecies) with indefinite distribution. The most important source of variation in U. dioica s. l. is probably polyploidy (2x, 4x; x = 13). The complex comprises an ubiquitous tetraploid cytotype (U. dioica s. str.) and several obscurely defined relict 2x taxa. The cytogeographical analysis through Europe (770 populations / over 3 200 individuals) revealed marked distribution pattern of U. dioica s. l. cytotypes. We identified 106 diploid populations (13%) and 633 (82%) tetraploid populations. For the first time we detected triploid and pentaploid level (from mixed populations). Prevailing tetraploid U. dioica s. str. is predominantly synanthropic, whereas diploid taxa strictly occur in primary and relict habitats (primarily alluvial forests, tundra, Mediterranean mountains). The analysis of the absolute genome size of individuals from U. dioica clade and other closely related taxa showed different values of 2x U. kioviensis (19 % higher than 2x U. d. subsp. subinermis) and 2x U. bianorii (33% higher than 2x U. d. subsp....
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Genome size studies in plants - from intraspecific variation to ecological consequences
Lučanová, Magdalena ; Trávníček, Pavel (advisor) ; Leitch, Ilia (referee) ; Šmarda, Petr (referee)
Nuclear DNA content (genome size) is one of the basic characteristics of living organisms. In the Angiosperms, the range of genome size is 2,300-fold, which raises questions about the causes and consequences of this tremendous variation. This thesis deals with genome size in plants from the level of intraspecific homoploid variation, through intraspecific ploidy variation, to interspecies comparisons. On various study systems we investigated the dynamics and ranges of genome size variation, tried to reveal possible associations between genome size and selected biological traits, and assessed the extent to which differences in genome size are manifested at the ecological and evolutionary level. As a means of estimating genome size we applied flow cytometry (FCM). In Taraxacum stenocephalum we conducted a detailed study of its enormous genome size variation. We carried out crossings of parents with various genome sizes and compared these parental genome sizes with those of F1 offspring. We also attempted to reveal the association of genome size with various growth traits. In Galium valdepilosum and Arabidopsis arenosa we carried out an extensive flow-cytometric ploidy level screening and compared the distribution and ecological preferences of detected cytotypes. We studied the Andean genus...
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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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Significance of polyploidy and hybridization in evolution of European taxa of genus Arum
Podobová, Tereza ; Urfus, Tomáš (advisor) ; Hojka, Jakub (referee)
Polyploidy and hybridization are significant evolutionary trends that occur in a wide variety of plant species. This bachelor thesis includes current knowledge and data on arums with a focus on polyploidization and hybridization of the genus Arum. The change in morphology depending on the polyploidy can affect not only pollination and the associated generative reproduction. Several studies have revealed a possible correlation between ploidy levels and geographical occurrence. Hybrids are rarely described, mainly on the basis of chromosomal numbers and morphology. Rare findings of natural hybrids could be more frequent in the future with more intensive research and could have medical potential. Key words: polyploidy, hybridization, Arum, geographical occurrence, spadix
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Influence of temperature on the shifts in sexuality of gynodioecious species Stellaria graminea (Caryophyllaceae)
Krtilová, Eliška ; Slovák, Marek (advisor) ; Macková, Lenka (referee)
Sexual polymorphisms represent an essential phenomenon in the evolution and reproduction of flowering plants. One of the types of sexual polymorphisms is gynodioecy, a phenomenon in which a plant species forms morphologically and functionally hermaphrodite, but also female individuals. However, the stability of sexuality expression of both types can be influenced by environmental factors, what might, finally, lead to shifts in sexuality (from hermaphrodites to females and vice versa). These changes are often very dynamic and can have a significant positive but also negative effect on genetic variability and overall fitness of the species. The main content of the work will be the elaboration of a research on the given topic which will contain chapters focused on sexual polymorphisms in flowering plants, gynodioecy, the influence of environmental factors on the lability of sexual expression and its effects on genetic variability and overall survival of species. An important part will also be the inference of the potential impact of climate change on fitness and survival of sexually polymorphic plant species. The theoretical part of the work will also focus on the model species selected for subsequent master's thesis, specifically Stellaria graminea. It is a perennial polyploid species inhabiting the...
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Evolution of Vicia cracca L. - distribution of cytotypes, their genetic variation and growth traits
Eliášová, Anežka ; Münzbergová, Zuzana (advisor) ; Vallejo-Marin, Mario (referee) ; Vašut, Radim Jan (referee)
A lot of the research has been made in the field of plant polyploidy since the discovery of this phenomenon. However, the more we know, the more questions arise. Overall, the most insistent questions remain: How did the polyploids arise and become established? Is it advantageous to be polyploid? We chose a perennial herb Vicia cracca L. to study the causes and consequences of polyploidisation on microevolution of a diploid-tetraploid complex in central European conditions. First, evidence from both flow cytometry and molecular markers (allozymes, DNA sequences, microsatellites) confirmed a hypothesised autopolyploid origin of tetraploids. Based on allozymes, we proved that tetraploids are genetically richer than diploid ancestors. However, we showed that the conclusions depend on statistics used for genetic variation measurements. Nevertheless, tetraploids of V. cracca suffered lesser reduction in seed production after artificial selfing than diploids. We thus infer that they profit from multiple allele dosage, which can mask deleterious alleles. We also corroborated an existence of a central European contact zone of diploids and tetraploids and discovered two other contact zones in south-western and south- eastern Europe. The central European contact zone with several mixed-ploidy populations served us as...
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Genome size studies in plants - from intraspecific variation to ecological consequences
Lučanová, Magdalena
Nuclear DNA content (genome size) is one of the basic characteristics of living organisms. In the Angiosperms, the range of genome size is 2,300-fold, which raises questions about the causes and consequences of this tremendous variation. This thesis deals with genome size in plants from the level of intraspecific homoploid variation, through intraspecific ploidy variation, to interspecies comparisons. On various study systems we investigated the dynamics and ranges of genome size variation, tried to reveal possible associations between genome size and selected biological traits, and assessed the extent to which differences in genome size are manifested at the ecological and evolutionary level. As a means of estimating genome size we applied flow cytometry (FCM). In Taraxacum stenocephalum we conducted a detailed study of its enormous genome size variation. We carried out crossings of parents with various genome sizes and compared these parental genome sizes with those of F1 offspring. We also attempted to reveal the association of genome size with various growth traits. In Galium valdepilosum and Arabidopsis arenosa we carried out an extensive flow-cytometric ploidy level screening and compared the distribution and ecological preferences of detected cytotypes. We studied the Andean genus...
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Origin, inheritance and ecological sygnificance of apomixis in the genus Hieracium s.str.: the role of genetic and epigenetic mechanims
Pinc, Jan ; Mráz, Patrik (advisor) ; Hojsgaard, Diego (referee) ; Mandák, Bohumil (referee)
Apomixis (asexual reproduction by seeds) has the considerable potential in agriculture and crop breeding due to its ability to produce genetically identical progenies in a form of persistent propagules, i.e. seeds. However, the processes laying behind the origin of apomixis and connected molecular mechanisms are still unknown. Despite the fact, that apomicts are considered to be an evolutionary dead-ends, they are often more widely distributed than their sexual relatives (this phenomenon is commonly referred to as geographical parthenogenesis (GP). Although this phenomenon is studied for decades, its causes are still not fully understood. Importantly, several recent studies pointed out that apomicts with limited genetic variability can at some extent react to changing environment through changes in gene transcription by epigenetic modifications. It is generally assumed, that hybridisation and polyploidization played a crucial role in the emergence of apomixis. For this reason, presented studies test the putative origin of selected polyploid apomicts and if the interspecific hybridisation between diploid sexuals triggers polyploidization using predominantly polyploid and apomictic genus Hieracium s. str. Surprisingly, the presented study demonstrates the hybrid origin of almost all investigated...
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