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Morphological differentiation and distribution of taxa in the Galium palustre group
Dohnalová, Pavla ; Kaplan, Zdeněk (advisor) ; Chrtek, Jindřich (referee)
This work is focused on the polyploid group of Galium palustre. The process of polyploidization has significantly influenced the evolution of angiosperms and in the studied group led to the emergence of 4 cytotypes known so far. Two of the cytotypes are found in the Czech Republic, diploid and octoploid, distinguished as species Galium palustre and Galium elongatum, respectively. Both taxa are mostly considered as species, which differ in quantitative characteristics, but these show considerable phenotypic plasticity. Therefore, the exact extent of morphological variation, precise distribution and ecology of the species are still unknown. The flow cytometry was used to distinguish cytotypes; it also showed variation in genome size and revealed a new dodecaploid cytotype in the Czech Republic. Subsequent morphometric analysis identified characteristics suitable for distinguishing the individual cytotypes. The most reliable are the length and width of a stem, the length of the leaf, the length of the longest branch, the number of leaves in whorls, the length of the inflorescence and the length of the mericarp. Based on these results, herbarium specimens from several herbaria were examined. The results also showed slightly different ecological preferences of cytotypes and their distribution in the...
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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...
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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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Anthropogenic hybridization between selected cultivated and wild relatives from the genus Malus (Rosaceae)
Orlovská, Lívia ; Slovák, Marek (advisor) ; Chrtek, Jindřich (referee)
Hybridization is an important driver of plant evolution, but it can also pose a threat to the genetic integrity of species. A specific case is gene flow induced by human activity, or "anthropogenic hybridization." In addition to theoretical knowledge about hybridization, introgression, and the protection of genetic diversity, this thesis presents its importance and impacts using the example of a model system from the Malus genus. By analyzing the available studies on the subject, I compare and evaluate the state of European populations of the wild species Malus sylvestris, which is subject to hybridization and introgression mainly with the cultivated species Malus domestica. The data indicate a common hybridization between these species to varying degrees, with up to 37 % of hybrid individuals in the population. The human effect is significant, particularly through the intensification of landscape utilization, which results in more frequent secondary contacts between species and subsequent gene flow. However, the available studies about hybridization between these species are mostly local, and a comprehensive view of the issue is lacking. Indeed, in the Czech Republic and Slovakia, there are presently no comparable empirical investigations utilizing genetic data. Overall, it implies that it is...
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Evolutionary processes shaping the genus Urtica L. (Urticaceae) in Europe and adjacent areas
Rejlová, Ludmila ; Chrtek, Jindřich (advisor) ; Koutecký, Petr (referee) ; Temsch, Eva Maria (referee)
Although European flora belongs among the best explored, there are still several marginally studied groups. One striking example is the polyploid complex of Urtica dioica, with multiple rare diploid taxa, which are often found in remote and partly relict geographic ranges, in contrast to cosmopolitan tetraploid individuals, which occur in a variety of synanthropic habitats and have an unknown evolutionary history. The thesis primarily deals with the evolution of diploid taxa recognized in Europe and contiguous areas of Southwest Asia (Urtica dioica subsp. kurdistanica, U. d. subsp. pubescens, U. d. subsp. sondenii, U. d. subsp. subinermis). This can lay the foundation for understanding phylogenetic relationships and revealing the evolutionary history of polyploids (U. d. subsp. dioica). The study also concerns itself with other related species outside of the complex U. dioica, especially from the Mediterranean area. An extensive dataset of 7012 samples from 1317 populations in a cytogeographical study has been analyzed, which covers most of the currently accepted diploid subspecies of U. dioica. From the entire dataset, a set of 279 plants (evenly representing the geographical and morphological variation) was used to estimate the extent of phylogenetic and morphological differentiation. The...
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The origin and evolutionary significance of triploid hybrids in diploid-tetraploid contact zone in Tripleurospermum inodorum
Ryšavá, Hana ; Čertner, Martin (advisor) ; Chrtek, Jindřich (referee)
The presence of triploid individuals, whether hybrids arising from crosses of diploid and tetraploid plants, or spontaneously generated triploid hybrids diploid populations, is increasingly important in plant populations. However, the possible evolutionary role of the triploid hybrids is closely connected to the frequency of their occurrence, to their relative fitness (compared to parental cytotype) and fertility. As a model plant I choosed Tripleurospermum inodorum, in which a relatively frequent occurrence of triploid hybrids was documented in mixed populations of tetraploids and diploids. This annual plant achieves realy quick its reproductive maturity and is easily cultivated, making it an ideal model for cultivation and pollinating experiments. Compared to parental cytotypes, the triploid hybrids of T. inodorum take approximately the same (mostly mediated) fitness values. In vitro conditions were cultivated to measure of germination rates. Germination rate of triploid seeds was comparable to diploid parental cytotype. In the subsequent comparative cultivation, nearly 150 plant individuals (2x, 3x, 4x, and aneuploid cytotype) in the greenhouse showed that the triploids had intermedial values of their parental cytotypes or close to one of the parents. Thus, the vitality of the triploid plants is...
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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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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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Variation and interspecific hybridization of Elymus repens and E. hispidus
Bartošová, Romana ; Urfus, Tomáš (advisor) ; Chrtek, Jindřich (referee)
Family Poaceae is one of the most derived groups of monocots. Major mechanisms of grasses evolution and particularly of tribe Triticeae and genus Elymus are polyploidisation and hybridisation. Presented diploma thesis assessed frequency and direction of hybridisation between Elymus hispidus and E. repens in Central Europe. Thesis also evaluated evolutionary importance (significantly higher ratio of hybridisation and polyploidisation) of hybrid swarm in Nature Reserve Čertoryje (Bílé Karpaty Mountains/the White Carpathians, the Czech Republic). Putative hybridizing populations were 14,4 % of sampled localities, i.e. direct presence hybrids (7,9 %) or both parental species (8,4 %). Aneuploids and higher polyploids were found exclusively in Čertoryje hybrid swarm, except one putative DNA nonaploid plant. The genome in situ hybridisation confirmed and improved knowledge of particular species/cytotypes chromosome counts and further specified their genome composition. GISH newly characterized genome composition of interspecific hybrids and higher allopolyploids and revealed their heterogeneous origin. Flow cytometry revealed continuum of absolute genome sizes among parental species and their hybrid. The continuum was rather asymmetric in direction towards E. hispidus. Model hybrid swarm Čertoryje produce...
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