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Polyploid speciation of the genus Anthoxanthum in Europe
Khodlová, Zuzana ; Trávníček, Pavel (advisor) ; Štech, Milan (referee)
Eight of fifteen species in genus Anthoxanthum (Poaceae) can be found in Europe. Five of them are perennials forming A. odoratum complex, the remaining three are annual, more or less mediterranean taxa (A. aristatum, A. ovatum and A. gracile). Within the A. odoratum s. l. complex the following taxa are distinguished: widely spread A. odoratum s. str. (4x; 2n = 20), arcto-alpine A. alpinum (2x a 4x; 2n = 10 and 20), Madeiran endemic species A. maderense (2x; 2n = 10), endemic species of Balkan mountains A. pauciflorum (2x; 2n = 10) and the Iberian peninsula endemic A. amarum (?x; 2n ~ 90). The aim of this thesis is to clearify the unknown evolutionary relationships between the taxa, between the annuals and perennials, diploids and polyploids. The following questions should be answered in this study: 1) What is the origin and distribution of the rediscovered diploid perennial taxon and what is its relationship to the other members of the group; 2) What is the distribution pattern of the perennial taxa of the genus Anthoxanthum in Europe and what is their haplotype differenciation (overall distribution of the taxa and haplotypes and the existence of their sympatric occurence); 3) What evolutionary ties exist among the species and what is the origin of allotetraploid taxon A. odoratum s.str. The...
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Ploidy level as a key for understanding variation in the Dactylis glomerata agg.
Blahová, Pavla ; Chrtek, Jindřich (advisor) ; Petříková, Eliška (referee)
The genus Dactylis represents one of the longest studied cases of natural polyploid complex, including a widely distributed dominant tetraploid complex and several older, but less successful diploid endemics. The center of diversity lies in the Mediterranean region, where primary and secondary contact zones between subspecies of different ploidy levels occur. The tetraploid complex Dactylis glomerata is distributed throughout Europe and has also been introduced to the rest of the world because of its economic importance. Production of unreduced gametes, hybridization between differentiated subspecies and the creation of higher ploidy levels via triploid bridge played a role in its origin. Tetraploids prefer open or anthropogenically disturbed habitats, while diploids inhabit mainly forest understory or habitats close to water. Different flowering times often prevent interspecific hybridization. The taxonomy of the genus Dactylis remains unresolved, and morphological characteristics used to differentiate subspecies may be unreliable. Most studies focus on Mediterranean subspecies, while those from Central Europe require further attention. Key words: Dactylis, ecological niche, polyploidization, tetraploid complex, triploid bridge
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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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Morphological and ecological differentiation and distribution of taxa in the Galium mollugo group
Talpová, Julie ; Kaplan, Zdeněk (advisor) ; Štech, Milan (referee)
My thesis deals with three taxa of the polyploid complex Galium mollugo that occur in the Czech Republic. These are diploid G. mollugo and tetraploid G. album subsp. album and G. album subsp. pycnotrichum. These taxa are very similar to each other, their identification is difficult and exact values of the quantitative characters used for their separation are unknown. To date, there has been no study based on flow cytometry (FCM) and classical morphometrics analysis in this complex. By using them I wanted to bring new results and fill the gaps in scientific research. Primarily, I was investigating whether the individual cytotypes can be distinguished based on different genome size using FCM analyses. Another aim was to determine whether it is possible to define morphological and ecological differences between diploid and tetraploid taxa. The morphometrics included ordination and discrimination methods. I observed whether taxa could be distinguished by the naked eye and determined by measurement which characters are most suitable for identification. FCM analyses proved to be suitable to distinguish the two ploidy levels. I have been able to demonstrate by statistical methods that diploid and tetraploid taxa differ from each other, and I have also refined the characters that are most suitable for...
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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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Application of molecular methods in population genetic studies
Šurinová, Mária
A vast range of factors shape the genetic structure of plant populations. In this thesis, I focus on two of them. The first factor, polyploidization, is a process of chromosome set multiplication through whole-genome duplication within a single species (autopolyploids) or hybridization of two different species (allopolyploids). It rapidly brings changes into genomes, allowing species to occupy distinct niches, adapt to new habitats, colonize them, or adapt to changing environment in their native range. But it comes at a certain cost - difficulties in mitosis and meiosis, changes in cellular architecture. Furthermore, after cytotype establishment, new individuals have to deal with cytotype exclusion effect, competition with parental individuals and higher nutrition requirements. In this thesis, I present the effect of polyploidization on populations of three species- Arabidopsis arenosa, Aster amellus and Festuca rubra. The second factor changing the population genetic structure presented in this thesis is the fragmentation of populations. Population fragmentation can be caused by natural or anthropogenic activities and often leads to overall reduction in population size and reduced connectivity among fragments. Restricted gene flow may threaten long-term population survival due to inbreeding...
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Krahulec, František (referee)
The main drivers of microevolution in the genus Sorbus are interspecific hybridisation and polyploidy. The fate of new hybrid and polyploid taxa is determined by their mode of reproduction. Especially apomixis could be very advantageous for these new taxa. The S. aria agg. (subg. Aria) plays an important role within the genus since its members are involved in all hybridisation events and thereby is responsible for the substantial part of variation of the genus. Flow cytometry, molecular markers and multivariate morphological analyses were employed to evaluate the processes generating the variability in the S. aria group. Three ploidy levels were detected among species from subg. Aria in the Czech Republic. All of them could be found in the South Moravia, whereas only tetraploids occur in the Bohemia region. Moreover, most of the Czech taxa (5 out of 7) grow also only in the South Moravia which is therefore considered as a centre of diversity of the genus Sorbus in the Czech Republic. Flow cytometry seed screen revealed 7 modes of reproduction among the individuals from S. aria agg. A wide range of sexual and apomictic types of reproduction including reduced and unreduced gametes was detected. All of the diploid individuals are completely sexual. Among polyploid taxa, most of the species are...
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Effect of polyploidization on species invasive success
Líblová, Zuzana ; Münzbergová, Zuzana (advisor) ; Rooks, Frederick (referee)
Polyploid variants of many species of plants are strikingly frequently found among alien plants on all continents. They also very often have a much larger distribution range of its occurrence, compared to diploid plants in the place of their origin. In many cases, the polyploid cytotype also has increased tolerance to various stress factors or a physiological and morphological characteristics that allow them to survive the conditions in which the diploid plants would have little chance to survive. All this suggests that polyploidy is likely to bring plants an evolutionary advantage over their diploid ancestors, and polyploids therefore can successfully colonize new territories. This thesis summarizes the findings about the possible consequences of polyploidy at different levels in relation to their effects on the properties supporting plant invasive ability. It presents also known hypotheses dealing with possibilities of why plants become invasive after introduction. This is followed by sections devoted to flow cytometry, an important modern method for determining genome size and ploidy level. In conclusion it briefly describes the model species bird vetch (Vicia cracca) and the results of measurements of the degree of ploidy of seeds of this plant from Alaska and Japan.
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Ecological and evolutionary consequences of polyploidization
Pavlíková, Zuzana ; Münzbergová, Zuzana (advisor) ; Rooks, Frederick (referee)
The frequency of polyploidy in natural populations is much more common than previously thought, suggesting that polyploidy must bring their holders either long or at least short term evolutionary advantage compared with their diploid ancestors, because otherwise they would not expand massively. The thesis deals with the consequences of polyploidy for genome, meiosis, mode of reproduction and the resulting viability of polyploid plants. It also describes and evaluates the possible reasons for the evolutionary success of polyploid plants. It also described the creation polyploids in diploid populations, the interactions between diploids and polyploids and the mechanisms of creation of reproductive isolation between cytotypes. Further, I paid attention to the interactions between polyploidy, herbivores and pollinators. In conclusion, I mention methods of synthesis neopolyploid plants, the possibility of their use and methods of detection of ploidy in plants.
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Chumová, Zuzana (referee)
Genus Sorbus is a very complex group of vascular plants. Various genetic lineages which can be fixed by apomixis are driven by interspecific hybridisation and polyploidy. Species from S. aria agg. have the highest variation probably due to an extra mechanism - introgressive hybridisation. There are several concepts of the aggregate which are usually based on three main species: S. aria, S. umbellatta and S. graeca. Therefore, new microspecies are derived by genome doubling and hybridisation between the main species. Units of the aggregate are assessed differently as the distinction of taxa is very complicated due to the overlap of the morphological variability. The aggregate itself can be sometimes considered as a category for species of uncertain origin or identification. Four species from S. aria agg. occur in the Czech Republic. In addition, the conclusion offers questions that will be addressed in the master's thesis.
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