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Application for the Data Processing in the Area of Evolutionary Biology
Radakovič, Lukáš ; Burgetová, Ivana (referee) ; Očenášek, Pavel (advisor)
This Bachelor’s thesis describes the design and implementation of the application that has the task to verify the accuracy of the algorithm. Purpose of the algorithm is to analyze mechanisms used in the creation of the phylogenetic tree. The application allows users to specify different parameters of phylogenetic tree, its generation and subsequent analysis using an algorithm. Results of the analysis are written to the output file, giving the user the option of setting file path. Studied algorithm correctly estimates the participation of specific mechanism in the tree formation. Estimates of the absolute and relative share of changes in chromosome number and genome size are less than accurate results.
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Evolution of genome size in streptophyte algae genus Zygnema and its ecological consequences
Lukeš, Jiří ; Čertnerová, Dora (advisor) ; Lučanová, Magdalena (referee)
Genome size is a trait that varies 64,000 × across eukaryotic diversity. However, this variability has nothing to do with the complexity of organisms. The amount of DNA itself is however related to a number of phenotypic traits of organisms. Specifically, studies conducted on plants look for possible connections between genome size and the ecological requirements of individual species. Similar studies in microscopic algae are not abundant and often face a number of methodological problems. This thesis presents genome size data obtained by flow cytometry for 129 representatives of the genus Zygnema belonging to 68 evolutionary lineages. Measurements revealed a genome size range within this genus from 0.22 to 5.06 pg. At the same time, several lines showing considerable variability in genome size were described, which in many cases indicates possible polyploidization in this genus. The identification of an identical GC base pair ratio in selected putative polyploid and monoploid representatives supported the hypothesis of polyploidization. The general correlation of cell size and genome size within this group was also validated. Due to the known phylogenetic relationships between the measured lineages, the genome size evolution in the genus Zygnema was reconstructed. Further, possible relationships...
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Species and cytotype diversity of invasive Symphyotrichum species in Central Europe
Varvažovská, Adéla ; Slovák, Marek (advisor) ; Hodálová, Iva (referee)
The cytotypic variability of Aster species of the genus Symphyotrichum is relatively well-explored within the territory of North America, where this species originates. Unfortunately, in Europe, where Asters were originally introduced as ornamental plants, they have received limited attention in terms of their overall as well as cytotypic variability. The number of publications and data concerning cytotypic variability and karyology in Europe is very limited, with some reporting the occurrence of several species and higher ploidy level species complexes. Asters naturalize in many places, capable of reproducing both vegetatively and generatively, and primarily colonize habitats disturbed by human activities. As a result, they have been classified as invasive plant species. From a biosystematic perspective, Asters constitute a highly complex group due to their high morphological and karyological variability. This situation is further complicated by the phenomenon of polyploidy and intense interspecific and intraspecific hybridization. These factors contribute to the challenging task of identifying individuals and populations and assigning them to specific taxa. The aim of this thesis was to clarify the cytotypic variability of wild-growing Aster species of the genus Symphyotrichum (Asteraceae) in the...
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Temperate flora of Patagonia and specific points of its evolution
Koubek, Matěj ; Ptáček, Jan (advisor) ; Šrámková, Gabriela (referee)
Patagonia is one of the few regions in the Southern Hemisphere with a temperate climate, and therefore provides a unique environment for studying the evolution of the local flora. Patagonian plants, like their temperate counterparts in the Northern Hemisphere, show higher rates of polyploidy. Polyploidy is a widespread condition among plants that plays a key role in the adaptation of species to various extreme stress conditions. Climatic characteristics, glaciations or volcanic activity, for example, are factors influencing the distribution of organisms. This work focuses on the study of the Patagonian flora, in particular on alpine and steppe species and their biogeography in relation to the climate and geology of the area. It also discusses the relationship between polyploidy and this distribution. Specifically, this work focuses on the widely distributed model species Azorella prolifera, which exhibits three ploidy levels. However, we have zero knowledge of the occurrence of individual cytotypes. The distribution and properties of polyploids have not been studied to a sufficient level in the Southern Hemisphere. Only a fraction of the papers dealing with this issue focus specifically on Patagonian plants. A more comprehensive insight into this topic may lead to a better understanding of the...
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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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Evolutionary role of triploids in diploid-tetraploid populations of Arabidopsis arenosa and Cardamine amara
Voltrová, Alena ; Kolář, Filip (advisor) ; Chrtek, Jindřich (referee)
This thesis addresses the evolutionary potential of interploidy gene flow mediated by triploid individuals of two mixed-ploidy species, Arabidopsis arenosa and Cardamine amara, both from Brassicaceae family. In natural secondary contact zones formed by diploid and autotetraploid cytotypes, triploids of both species are rarely occurring, being represented only by 0.2 % and 2.5 % of individuals in A. arenosa and C. amara, respectively. Yet their role in gene flow between parental diploid-tetraploid populations remain unclear although genetic data confirmed significant traces of interploidy introgression. By crossing experiments of both species of triploids with their parental ploidies, I addressed the potential of triploids as mediators of gene flow. Specifically, the fertility of triploids and their ability to backcross with their diploid and tetraploid parents. Successful crosses involving triploids both as mothers and fathers demonstrated triploid's ability to form viable male and female gametes. A significant fraction of seeds produced out of these crossings was able to germinate and survive. The progeny was largely aneuploid, but both basic euploids were observed, demonstrating a clear pathway how triploids can backcross back towards diploid and tetraploid ploidies. In C. amara, field...
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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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triggers of asexual reproduction: on the crosslink between hybridization, asexuality, polyploidy and speciation on example of Cobitidae loaches
Marta, Anatolie ; Janko, Karel (advisor) ; Arai, Katsutoshi (referee) ; Trachtulec, Zdeněk (referee)
(in English) Sexual reproduction is considered a nearly universal feature of all eukaryotic organisms and has been hypothesized to be their ancestral state. Sexual reproduction is mainly represented by meiotic division, recombination, production of haploid gametes and fertilization. Although molecular and cytological mechanisms underlying meiosis are highly conservative they may be disrupted in numerous ways leading to the emergence of so-called asexual lineages. The proximate origins of asexuality may differ for particular taxa. In vertebrates, asexuality frequently is triggered by interspecific hybridization. Nowadays "classical" theories predict that asexuals should not be able to persist on a long-term evolutionary scale. However, the hybrid lineages have to overcome short-term disadvantages, such as postzygotic barriers ranging from complete hybrid sterility to altered meiosis resulting in asexual reproduction and even ploidy elevation. Despite that hybrid sterility is one of the most common outcomes of interspecific hybridization, however various lineages found their ways to alleviate these problems and produce viable clonal gametes. The knowledge about proximate mechanisms of unreduced gamete formation in asexual lineages is very limited as many studies were restricted due to methodological...
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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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