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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...
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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...
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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...
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Evolutionary and conservation consequences of interspecific hybridization in rare plant species
Vít, Petr ; Suda, Jan (advisor) ; Frajman, Božo (referee) ; Španiel, Stanislav (referee)
3 Summary 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...
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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...
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Libanotis pyrenaica - a unique polyploid complex in the family Apiaceae
Přívozníková, Hana ; Chrtek, Jindřich (advisor) ; Vít, Petr (referee)
6 Abstract Libanotis pyrenaica is sometimes neglected representative of Czech flora, a member of Apiaceae family. It grows in xerothermic habitats, on basic soils, particularly on limestones. It can be found on shrubby, stony or grassy slopes, screes, in quarries, pastures, light forests, along the roads and railroads, river banks and in castle ruins. Libanotis pyrenaica is native to the Czech Republic, but is spreading secondarily to many habitats (along the river banks, railroads). Its secondary occurrence has been documented in e.g. Eastern Bohemia. There are two ploidy levels known in the Czech Republic: 2n = 2x = 22 and 2n = 4x = 44. Diploid plants were found in Southern Bohemia (limestones of Sušicko-Horaždovice region, Českokrumlovské Předšumaví region), while the tetraploid plants were detected in Eastern Bohemia and Southern Moravia. In contrast, diploids seem to prevail throughout Europe. However, exact frequency, geographical occurrence and differentiation of both ploidies are unknown up to date. Key words: Libanotis pyrenaica, Seseli, Moon Carrot, diploid, tetraploid, cytotype differentiation, Apiaceae, flow cytometry
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Microevolutionary processes in the Czech endemic Campanula bohemica
Hanušová, Kateřina ; Suda, Jan (advisor) ; Vít, Petr (referee)
The genus Campanula L. - bellflower - is the largest group of the family Campanulaceae with a subcosmopolitan distribution and poorly resolved infrageneric classification. The evolutionary history of the genus has been shaped by a number of microevolutionary processes, including interspecific hybridization, genome duplication and geographical isolation, that resulted in the genesis of several endemic or geographically restricted species. The centre of endemism in the Czech Republic lies in subalpine altitudes of the Jeseníky and the Krkonoše (Giant) mountains, where three endemic taxa can be found: C. gelida Kovanda, C. rotundifolia L. subsp. sudetica (Hruby) Soó and C. bohemica Hruby. Despite their evolutionary and biogeographical value, there is a lack of information about their phenotypic variation, population structure, evolutionary history and processes acting in their populations. A critical assessment of these topics would require application of modern biosystematics tools. Campanula bohemica is an endangered neoendemics of higher altitudes in the Krkonoše Mts., closely related to C. scheuchzeri Vill., native to the Alps. The endemic species often grows in sympatry with related and morphologically similar C. rotundifolia. The incidence of intermediate morphotypes suggest that both species can...
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Risk of hybridization of threatened P. fruticosa with cultivated Prunus species
Musilová, Lenka ; Vít, Petr (advisor) ; Zahradníček, Jaroslav (referee)
Many agriculturally important fruit trees occur in the genus Prunus, among other also Sour cherry (Prunus cerasus) and Sweet cherry (Prunus avium). P. cerasus is considered to be an allopolyploid hybrid originated by hybridization of Prunus fruticosa (2n = 4x = 32) and P. avium (2n = 2x = 16). The world production of sour cherry fruit (P. cerasus) in 2008 is estimated to be more than 1, 15 million tones. Prunus fruticosa is a steppe (forest steppe) relict species, severely endangered in the Czech Republic (C2). The main threat of P. fruticosa are both the direct and indirect human activities, causing, above all the loss of natural biotopes and hybridization with cultivated species that ran wild to the nature. P. fruticosa hybridizes all over its occurrence area with wild P. cerasus (Sour cherry; which is not primary species of the Czech Republic) and originates fertile hybrid Prunus × eminens. The results of existing studies indicate that the hybrids are more common in the central Europe and that the frequency of hybridization rises towards the west. Such phenomenon is related to human activities (cherries cultivation and landscape changes). Many authors consider hybridization to be the main cause of endangerment of this species and noticed that in many habitats the hybrids could totally replace...
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