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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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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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Evolutionary history of tetraploid representatives Galium pusillum group (sect. Leptogalium) in central Europe. Allopatric differentiation of Czech endemic species G. sudeticum
Knotek, Adam ; Kolář, Filip (advisor) ; Chrtek, Jindřich (referee)
The presented study tries to reveal the evolutionary history of polyploid complex Galium pusillum aiming on a rare czech endemic species G. sudeticum, an ideal model to study allopatric speciation in the context of Central European (post)glacial development. The species G. sudeticum grows in Krkonose Mts. and on serpentines in western Bohemia (Slavkovský les) more than 200 kilometers away. Our morphological and molecular data suggest a clearly different history of its two isolated areas. The populations in Krkonose Mts. are probable relics of mountainous species G. anisophyllon which was there on its northern border of occurence and hybridized with lowland species G. valdepilosum during postglacial vegetations shifts. This fact is well supported by intermediate position of Krkonose Mts. populations in both morphological and molecular AFLP analyses and by sharing the same chloroplast haplotype with geographically close lowland populations. On the other hand the serpentine lowland populations in western Bohemia are both morphologicaly and genetically indistinguishable from G. valdepilosum. Distinct genetic lineage of few populations belonging to G. valdepilosum (incl. one traditionaly referred as G. sudeticum) was found in western Bohemia and Bavaria, located on relic stands (calcareous and serpentine...
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Ecological consequences of polyploidization in populations of the wetland plant Butomus umbellatus
Rydlo, Jan ; Fér, Tomáš (advisor) ; Trávníček, Pavel (referee)
This thesis aimed on comparison of environmental requirements and morphological and biological traits of diploid and triploid cytotypes of wetland plant flowering rush (Butomus umbellatus), occurring in Eastern Slovak Lowland in unique mixed populations, and to develop primers for variable microsatellite loci suitable for further genetic studies. In total, 72 populations of Butomus umbellatus were found. The analysis of relative genome size by the flow cytometry (FCM) technique revealed 34 exclusively triploid cytotype populations, 8 exclusively diploid populations and 30 mixed populations of Butomus umbellatus. In mixed populations, the numbers of diploid and triploid individuals are quite equivalent and the plants create combined compact communities. Analyses of environmental characteristics of sites with specific cytotypes (PCA, RDA, ANOVA) revealed no difference in site requirements of diploid and triploid Butomus umbellatus plants. Morphometric analyses (PCA, CDA) of traits of 36 diploid and 54 triploid plants confirmed differing morphology of both cytotypes occurring in the nature. Subsequent replanting of these plants into pots and cultivation further increased these differences. The ratio of width and length of internal perianthium is the most reliable parameter to distinguish diploid and...
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Application of molecular methods in population genetic studies
Šurinová, Mária ; Münzbergová, Zuzana (advisor) ; van Loo, Marcela (referee) ; Mandák, Bohumil (referee)
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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Reproductive interactions between diploids and triploids of flowering rush (Butomus umbellatus) and their evolutionary potential for mediating inter-ploidy gene flow
Petříková, Eliška ; Čertner, Martin (advisor) ; Prančl, Jan (referee)
Contact zones of cytotypes harbour a unique opportunity to study the dynamics and evolution of mixed-ploidy systems. Butomus umbellatus (flowering rush) is one of a few species in which diploid and triploid cytotype is present in nature. The first known mixed-ploidy populations of B. umbellatus were discovered in south-eastern Slovakia during the previous studies. Common occurrence of the species in an area with substantially natural dynamics of wetland ecosystems represents a unique model system for unbiased comparisons of traits and genetic diversity between diploid and triploid individuals along with their dispersal capabilities on a landscape level. The main aim of of this thesis is to uncover the truth behind evolutionary processes that are taking place in the contact zone of diploid and triplioid cytotype of B. umbellatus in south-eastern Slovakia. Using flow cytometry and molecular methods (microsatellites) we will test whether this is a primary or secondary contact zone and assess the level of genetic variability between individuals and populations of both cytotypes. Using the analysis od microsatellite loci we discovered that the contact zone of cytotype is of both primary and secondary character and gene flow between cytotypes was also detected. These results were supported by high production and...
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