National Repository of Grey Literature 20 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Local edaphic adaptation in the Minuartia verna group
Koberová, Tereza ; Chrtek, Jindřich (advisor) ; Vít, Petr (referee)
Plants that have adapted their metabolism to life in soils containing heavy metals are suitable candidates for studying local adaptation. Although soils containing heavy metals and the plants that grow in them have attracted the attention of botanists for several decades, there is a lack of studies that address the ecological-evolutionary questions related to the pre-adaptation of plants to these challenging conditions. This work focuses on the species Minuartia verna, which includes populations growing in mine dumps, populations growing in serpentinite, and populations growing in non-toxic substrates. Local adaptation and pre-adaptation were studied using a reciprocal experiment involving populations representing each of the three aforementioned groups. I measured several vegetative and generative plant traits, fitness was then calculated based on these traits. A comparison of plant fitness of the populations grown in different soils suggests that non-metallicolous populations are not pre-adapted to grow in soils contaminated with heavy metals. However, all populations thrived well in serpentine soil, indicating a genetic adaptation to this substrate. The analysis of metal content in plants indicates that they function as excluders of Ni and Pb, with higher concentrations of these metals found in...
Assessing the threat of hybridization between Prunus fruticosa and cultivated Prunus species
Musilová, Lenka ; Vít, Petr (advisor) ; Chrtek, Jindřich (referee)
Presented thesis evaluates the risk of ongoing hybridization (antropohybridization) in highly endangered Prunus fruticosa in the Czech Republic and selected adjacent countries. Absolute genome size analysis (estimated by flow cytometry) combined with both numeric and geometric morphometrics were used for evaluation of hybridization. Prunus fruticosa frequently hybridize with naturalized Prunus cerasus (emerging tetraploid hybrid Prunus ×eminens) and native Prunus avium (forming triploid hybrid Prunus ×mohacsyana). Discrimination between P. ×eminens and P. ×mohacsyana is difficult, when using leaf morphology characters only, so the occurrence of triploid hybrids was strongly underestimated in the Czech Republic (only tetraploid hybrids were reported). Both hybrids are surely differentiated using flow cytometry analysis (based on different ploidy level). The majority of analyzed populations is formed by either individuals of pure P. fruticosa or one of the mentioned hybrids. Only four populations were mixed. Continuous variability in absolute genome size was found in two of them, which may indicate hybrid swarm forming (incl. primary hybrids and backcrosses). Our findings can be considered only as indirect evidence for introgression, which needs to be confirmed by molecular markers (for example...
Differentiation in the polyploid complex Libanotis pyrenaica (Apiaceae)
Přívozníková, Hana ; Chrtek, Jindřich (advisor) ; Vít, Petr (referee)
Polyploidization belong to principal evolutionary mechanisms in plants. Although it is rather rare in the family Apiaceae, there are several interesting polyploid complexes here. The present study deals with Libanotis pyrenaica, species three previously reported ploidy levels, namely diploid (2n = 2x = 22), tetraploid (2n = 4 x = 44) and most likely very rare triploid (2n = 3x = 33). The present study aims at geographical pattern of ploidal diversity in central Europe, genetic variation and selected biological features of this species. Flow cytometru, analysis of two chloroplast DNA markers (trnF-trnL and cp018-cp020), morphometrics and in vitro germination experiments were used. The tetraploid cytotype occurs throughout the studied area; in the Czech Republic it was found in the České středohoří Mts., southern Bohemia and Moravia, in Slovakia it especially in the Carpathian mountains in western and central parts of the country and in the Pieniny Mts. in the northeast. Tetraploid cytotype occurs mainly in central-east Europe; in the Czech Republic it is common in the lowlands along the river of Labe and locally in Moravia; in Slovakia it was found along the river of Váh, in the Slovenské rudohorie Mts. and in the Belanské Tatry Mts. A mixed-ploidy population (2x, 4x) was discovered in southern...
The variability of the species Urtica dioica in the Czech Republic
Rejlová, Ludmila ; Urfus, Tomáš (advisor) ; Vít, Petr (referee)
The genus Urtica L. is represented by three species occurring in the area of the Czech Republic. The most common Urtica dioica L. represents a highly variable group with number of intraspecific taxa. The most common source of variability in Urtica dioica is probably polyploidy (min. 2 ploidy levels - 2x and 4x). Another source of the variation in this species is dioecy. A small percentage of individuals in dioecious populations are actually monoecious. The study of these individuals can potentially extend our knowledge of the evolution of Dioecy. The species Urtica dioica is frequently confused with the closely related diploid taxon Urtica kioviensis Rogow., which relates to the study of Urtica dioica because of their similar ecological preferences and general affinity. The aim of this review is to summarize existing knowledge of the species with results of a pilot sampling and analyses, which identified several ploidy levels with the center of abundance of the relict diploid in primary willow-poplar forests of lowland rivers. These issues will be further examined in a subsequent master's thesis, with focus on the morphological differentiation and the affinity of ploidy levels. Since the rarest and the most targeted taxa, resp. cytotypes, of the genus Urtica occur exclusively in the willow-poplar...
Evolutionary and conservation consequences of interspecific hybridization in rare plant species
Vít, Petr
Hybridization plays an important role in the evolution of vascular plants. It can have both positive and negative consequences, ranging from the origin of new species on the one hand to the extinction of taxa through introgression on the other. These effects may be pronounced in geographically restricted or rare species. The core of this thesis are three case studies addressing interspecific hybridization involving rare angiosperm species. Finally, the thesis is completed with a study considering hybridization as a source of variation and new species. The coexistence of frequent primary hybrids with their parental taxa was revealed in the system comprising the rare species Cerastium alsinifolium and its widespread counterpart C. arvense. The spatial distribution of the endemic species and its habitat preferences were elucidated. In contrast, comparatively rare hybridization events were found in the Nymphaea alba - N. candida complex. Although it has been assumed that water lilies hybridize freely, our karyological data do not support this hypothesis. Hybrids, therefore, do not present a serious risk to either of these rare species. The third study describes interspecific hybridization in the spore-bearing genus Diphasiastrum. Traditionally, three basic and three hybridogenous species are recognized...
Genome size in the evolution of cockroaches
Stuchlíková, Magdalena ; Janšta, Petr (advisor) ; Vít, Petr (referee)
Genome size or nuclear DNA content is a a trait which varies greatly among living organisms, with no apparent relashionship between genome size and organismal complexity. It is usually described using the C-value as either a number of base pairs or picograms of DNA. Unresolved questions regarding mechanisms influencing genome size and relationships between genome size and other organismal traits are together known as the C-value enigma. Genome size is known to positively correlate with cell size and negatively with developmental and cell division rate. A maximum constraint of 2 pg has also been proposed for haploid genome sizes of holometabolous insects. Despite the fact that there are about one million described insect species, genome sizes are only known in a fraction of them. This thesis thus aims to extend the dataset of known insect genome sizes by as many species of cockroaches (Blattodea) as possible. Another aim is to compare results with known phylogeny and also to compare difference in genome size between sexes. Flow cytometry was used for genome size estimations, which is a rapid, simple and effective method, also suitable for study of ploidy levels and other cellular charasteristics.

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4 VÍT, Pavel
2 Vít, Přemysl
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