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Evolutionary forces of Central European taxa of the genus Dactylorhiza
Bílá, Klára ; Urfus, Tomáš (advisor) ; Figura, Tomáš (referee)
Genus Dactylorhiza, comprising green terrestrial orchids, belongs to of the most taxonomically complex groups of Europeran flora. Basic species often hybridise between each other and there is a lot of taxonomically challenging hybrids and hybridogenous lineages. Essential parental species of majority of hybrids and hybridogenous lineages are D. incarnata, D. maculata and D. fuchsii. Sister genus of Dactylorhiza is Gymnadenia which shares some similar features with Dactylorhiza species. Dactylorhiza viridis, formerly classified into the genus Coeloglossum, is the earliest diverged species. Diversity centre probably takes place in the Mediterranean Basin from where Dactylorhiza species migrated back to the Central Europe in postglacial. Major force of the genus evolution is polyploidisation which together with hybridisation leads to establishment of allopolyploid lineages. Unique feature of many orchids (including genus Dactylorhiza) is partial endoreduplication, which somatic endopolyploidisation of certain part of genome takes place. Pollination type is also important for Dactylorhiza microevolution. Deceptive flowers of Dactylorhiza genus are mainly pollinated by naive bumlebees but even beetles or ants can be pollinators. Majority of Dactylorhiza species are threatened by habitat loss during last decades....
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Evolution of the genus Malus with a particular reference to old and local cultivars
Polcar, Václav ; Urfus, Tomáš (advisor) ; Macková, Lenka (referee)
The following work deals with the genus Malus in terms of the significant diversity that this genus represents. It summarizes a basic knowledge about the taxonomic position and world centers of the genus evolution. Part of the thesis also discussed reproductive mechanisms as a source of the genus diversity. The thesis then focuses on the species Malus domestica, its evolution and the hybrid origin. In this context, old varieties of apple trees, their significance and pomologically important regions of the Czech Republic are presented. An integral part of this work is also devoted to the protection of old varieties, its limits and possibilities. The protection of old varieties also encompasses the extensive orchard as an important agroecosystem. Finally, different Czech regions are compared with respect to the quantity of reported old varieties.
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Hybridization as a source of threat to Urtica kioviensis
Pekařová, Michaela ; Urfus, Tomáš (advisor) ; Štěpánek, Jan (referee)
Hybridization can have a negative impact on native taxa, which means a risk to plant biodiversity. Urtica kioviensis (2x) is a rare species of that grows in mixed populations together with two cytotypes (2x and 4x) of the closely related taxon Urtica dioica (stinging nettle). The presence of hybrids has been described in the past. Here I studied hybridization at localities in the Czech Republic (PR Plačkův les a říčka Šatava, NPR Ranšpurk), Slovakia (PR Jurský Šúr), and Hungary (Kóny, Fehér-tó). These taxa and their hybrids were studied by flow cytometry and morphometric analysis. Both methods provided evidence of ongoing hybridization. The continuous pattern at the diploid level suggests homoploid hybridization and subsequent introgression affecting mainly U. kioviensis. The possibility of backcrossing at the diploid level was also confirmed by analyses of pollen fertility or staining. Triploid individuals were also detected, showing differences in relative genome sizes and different positions relative to the parental taxa in morphometric analyses. Based on these results, it's not possible to reliably determine their origin. Heteroploid hybridization is likely to occur, but its presence cannot be definitely confirmed or excluded. Hybrids are common in mixed populations of U. kioviensis and mean a...
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Genome size variability and its relationship towards selected biological characteristics of arachnids
Šilhavá, Veronika ; Opatová, Věra (advisor) ; Urfus, Tomáš (referee)
Genome size, also called C-value, describes the amount of DNA contained in haploid set of chromosomes in organism. Knowledge of this value can be useful for example as indicator of technical difficulty and financial cost of projects using genome seqencing, or it can be used for taxonomic purposes as well. Genome size encompasses immense variability across the animal kingdom. We also encounter variability among arachnids, even between species within the same genus. However, the relationship between genome size and biological characteristics of arachnids has not been examined so far. In this thesis, I assembled genome size data for all arachnid orders alongside with a variety of their biological characteristics. These traits were subsequently mapped onto the phylogenetics trees. In certain arachnid orders, the genome size could be related to the body size, life span and potentially also to ecology (e.g. web type, retreat). Unfortunatelly, genome size data are available only for a small portion of Arachnida diversity, which complicates the interpretation.
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Invasiveness and hybridisation in evolution of closely related species
Gruntová, Martina ; Hojka, Jakub (advisor) ; Urfus, Tomáš (referee)
Plant invasiveness, or the extensive spreading of a plant species into new and non-native areas, is an important and frequently discussed process in botany, influenced by many internal and external factors that determine how a plant will spread and how successful will the spreading be. One of the important factors affecting the level of invasiveness is the ability to hybridise and also ability to become polyploids, because via those processes plants acquire genetic variation that can provide advantageous predispositions for their dispersal. Plants and their spreads are also influenced by external ecological factors, i.e. the environment in which they grow, other species sharing the same habitat, and e.g. climate change or human activity, which change the environmental characteristics and therefore also the areas of distribution. The aim of this thesis is to find links between hybridisation and the success of plant dispersal, and subsequent invasiveness (i.e. the spread of a plant in a non-native range), by using the genus Rorippa as a model. The Central European lineage of lowland species of the genus Rorippa represents a suitable group to study these processes due to the frequency of hybridisation, the variability of ploidy levels and the previously detected invasiveness of one of the species (R....
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The role of sexual reproduction in the invasive behavior of polyploid species complexes in alien plants
Jarůšková, Dominika ; Slovák, Marek (advisor) ; Urfus, Tomáš (referee)
Alien plants have a significantly negative impact on the composition and structure of resident communities. They might cause a remarkable decrease in their biodiversity and even severely threaten the existce of rare species. One of the factors that can accelerate invasive behaviour of alien species is whole-genome duplication (polyploidy), which can, via increased genetic diversity, improve overall fitness, reproduction abilities and competitiveness of polyploid cytotypes compared to their diploid counterparts. This work represents a literature review focused on the reproductive mechanisms of invasive species and the role they play in their invasive behavior. Reproduction is further analyzed in the context of polyploidy, with a special focus on the effects of polyploidy on sexual reproduction. Last but not least, the work presents and discusses case studies that deal with selected invasive polyploid species complexes and analyze the success of their sexual reproduction in their native as well as invaded distribution range. Key words: alien species, polyploidy, sexual reproduction
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Krahulec, František (referee)
The main drivers of microevolution in the genus Sorbus are interspecific hybridisation and polyploidy. The fate of new hybrid and polyploid taxa is determined by their mode of reproduction. Especially apomixis could be very advantageous for these new taxa. The S. aria agg. (subg. Aria) plays an important role within the genus since its members are involved in all hybridisation events and thereby is responsible for the substantial part of variation of the genus. Flow cytometry, molecular markers and multivariate morphological analyses were employed to evaluate the processes generating the variability in the S. aria group. Three ploidy levels were detected among species from subg. Aria in the Czech Republic. All of them could be found in the South Moravia, whereas only tetraploids occur in the Bohemia region. Moreover, most of the Czech taxa (5 out of 7) grow also only in the South Moravia which is therefore considered as a centre of diversity of the genus Sorbus in the Czech Republic. Flow cytometry seed screen revealed 7 modes of reproduction among the individuals from S. aria agg. A wide range of sexual and apomictic types of reproduction including reduced and unreduced gametes was detected. All of the diploid individuals are completely sexual. Among polyploid taxa, most of the species are...
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Ecological and evolutionary processes in primary contact zone of cytotypes of Knautia arvensis agg.
Hanzl, Martin ; Kolář, Filip (advisor) ; Urfus, Tomáš (referee)
Genome duplication events have played a crucial role in plant evolution. According to recent estimates, nearly all the angiosperms are ancient polyploids. However, establishment of new polyploid lineages within diploid populations seemed to be very unlikely, based on theoretical analyses. Reproductive interactions between the cytotypes (so-called "minority cytotype exclusion") and resource competition might eventually lead to polyploid extinction. On the other hand, the whole variety of factors may compensate both processes under natural conditions (e.g. autogamy, assorative mating, spatial separation of cytotypes). Polyploid establishment in sympatry with diploid progenitor might thus not be as restricted, as previously thought. Subsequent cytotype coexistence may represent a stable equilibrium, or just a transition leading to extinction of one chromosomal race. It is usually almost impossible to discriminate between these alternatives. Polyploid range expansions are usually accompanied by competitive exclusion of diploid cytotype or colonization of new areas and habitats. When two cytological races meet, zones of contact are often formed. Contact zones could be divided into primary and secondary ones. Primary contact zones arise as a consequence of new polyploid emergence within the progenitor's...
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