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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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Flow cytometry in insects biosystematics
Javůrková, Jaroslava ; Šípek, Petr (advisor) ; Sadílek, David (referee)
The size of the genome, or DNA content in cells, is expressed using the so-called C-value, i.e. the weight of DNA in units of pg, or as 2C-values for the DNA content in somatic cells of diploid organisms. A simple method used, among other things, to determine the size of the genome is flow cytometry. This method has traditionally been very popular, especially among botanists, where it is mainly used in taxonomic and population studies or for determining the ploidy of individual lines. Conversely, genome size in animals and insects is relatively little studied. Of the more than a million described insect species, the genome size is known for only hundreds of them. This work provides information on the genome size of eighty-eight species of insects from selected orders of the Polyneoptera group - four species of earwigs (Dermaptera), four species of weavers (Embioptera), fourteen species of mantises (Mantodea), seventeen species of stick insects (Phasmatodea), forty-six species of grasshoppers, locusts, and crickets (Orthoptera), one species of termite (Isoptera, Blattodea) and two species of stoneflies (Plecoptera). The determined absolute genome sizes and variance rates were compared within individual orders, within the Polyneoptera group, and compared with the genome sizes of other insect taxa....
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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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Flow cytometry in insects biosystematics
Javůrková, Jaroslava ; Šípek, Petr (advisor) ; Sadílek, David (referee)
The size of the genome, in other words the content of DNA in the gametic cells of organisms, is expressed using the C-value indicating the number of nuclear base pairs in units of Mpb or the mass of DNA in units of pg. A simple method used, among other things, to determine the size of the genome is flow cytometry, which in recent years has been very popular, especially among botanists. The study of insects is lagging behind in regard to the number of described species of insect numbering more than one million in comparison to the number of species whose genome size is known (only a few hundred of them). This diploma thesis therefore aims to expand the dataset on the size of the genomes of representatives of the Polyneoptera group, to compare the data found within individual orders and to help understand the links of genome size to the evolution and ecology of insects. This work provides genome size information for eighty species of insects of the Polyneoptera group. The results showed the largest insect genome measured so far - the locust Dictyophorus griseus (149.33 pg), whose genome size exceeds the previously published results by several times. Key words: flow cytometry, genome size, c-value, Polyneoptera
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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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Genome size variation in microalgae and its evolutionary consequences
Čertnerová, Dora
Eukaryotic organisms exhibit tremendous variability in genome size with no apparent connection to their biological complexity. Although this variation is known to correlate with numerous phenotypic traits, its evolutionary consequences remain widely unknown. This particularly applies to microalgae, where the genome size estimation is often methodologically challenging. Yet, microalgae represent a promising model group to study genome size evolution owing to their lower body complexity, short generation time and large population sizes, the latter two allowing them to quickly respond to environmental challenges. The main aim of this thesis was to enhance our understanding of genome size variation in microalgae and its evolutionary consequences. To do so, together with my co-authors, I summarized the flow cytometry (FCM) protocols used for microalgae and microorganisms possessing small genomes and addressed their limitations resulting mainly from insufficient amounts of biomass, difficulties with nuclei extraction and prominent background noise due to presence of various pigments and secondary metabolites. Further, I provided best practice recommendations that include, among others, analysing young cultures, avoiding long-term cultivation, and testing different isolation buffers and nuclei isolation...
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Genome size variation in microalgae and its evolutionary consequences
Čertnerová, Dora ; Škaloud, Pavel (advisor) ; Boenigk, Jens (referee) ; Bureš, Petr (referee)
Eukaryotic organisms exhibit tremendous variability in genome size with no apparent connection to their biological complexity. Although this variation is known to correlate with numerous phenotypic traits, its evolutionary consequences remain widely unknown. This particularly applies to microalgae, where the genome size estimation is often methodologically challenging. Yet, microalgae represent a promising model group to study genome size evolution owing to their lower body complexity, short generation time and large population sizes, the latter two allowing them to quickly respond to environmental challenges. The main aim of this thesis was to enhance our understanding of genome size variation in microalgae and its evolutionary consequences. To do so, together with my co-authors, I summarized the flow cytometry (FCM) protocols used for microalgae and microorganisms possessing small genomes and addressed their limitations resulting mainly from insufficient amounts of biomass, difficulties with nuclei extraction and prominent background noise due to presence of various pigments and secondary metabolites. Further, I provided best practice recommendations that include, among others, analysing young cultures, avoiding long-term cultivation, and testing different isolation buffers and nuclei isolation...
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Comparative methods for studying adaptive traits of fungal symbionts
Veselská, Tereza ; Kolařík, Miroslav (advisor) ; Voigt, Kerstin (referee) ; Dvořák, Miloň (referee)
The kingdom Fungi encompasses an estimated 2.2 to 6.2 million species that occupy diverse environments, including aquatic, extremely dry, and hot or frosty habitats all over the world. To cope with adverse environmental conditions, fungi have developed numerous adaptations and life strategies, including symbiosis with other organisms, ranging from close, reciprocally beneficial (mutualistic) associations to severe pathogenic infestations. These interactions have an enormous impact on ecosystem functioning, with implications for agriculture and human health. For this reason, understanding the mechanisms enabling the successful development of fungal interactions is necessary for their efficient management. Recent advances in different 'omics' approaches have enabled us to compare species responses to the environment in a more complex way than before and to gain deeper insights into the adaptive mechanisms underlying specific life strategies. My thesis is divided into four main sections. In the first section, I sum up findings about adaptations of fungal symbionts of plants and animals. Then, I introduce two fungal genera, Geosmithia and Pseudogymnoascus, to which I applied comparative methods for tracking adaptive traits. The ecological diversity of the genus Geosmithia allows to trace adaptive...
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