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Processes determining the stability of cytotype coexistence in plant populations
Nedomová, Anežka ; Čertner, Martin (advisor) ; Urfus, Tomáš (referee)
Multiplication of nuclear genome is considered one of the most important processes in the plant evolution. Neopolyploids arise in a diploid population by merging of two unreduced gametes or through "triploid bridge". However establishment of a new polyploid in the current population is not easy. Polyploid has to overcome through various mechanisms (like a self-pollination, nonrandom pollination, etc.) "the minority cytotype exclusion" and increase their frequency in the population. Diploids and polyploids differ in ecological demands and competition abilities. There is no correlation between ploidy and wide ecological amplitude or competition abilities. With the current knowledge, we can not determine in which case is the mixed population stable. There is an assumption that the population contains two closely related species simply can not be stable, and therefore all cytotype mixed populations are unstable. Powered by TCPDF (www.tcpdf.org)
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Microevolutionary processes and inter-cytotype interactions in mixed-ploidy populations
Trávníček, Pavel ; Suda, Jan (advisor) ; Frajman, Božo (referee) ; Zozomová, Judita (referee)
[Abstract] This thesis is aimed at better understanding of cytotype co-existence in mixed- ploidy populations with an emphasis on a microevolutionary processes behind it. Our past knowledge was based on a few thoroughly investigated model taxa like Chamerion angustifolium and Heuchera grossulariifolia, but some generalizations seem to be premature in the light of new findings. A detailed research of other taxa included in the thesis showed that polyploid complexes can vary dramatically in their ability to cope with the co-existence of cytotypes in mixed-ploidy popu- lations. Whereas mixed-ploidy populations are virtually lacking in some species (an example being Vicia cracca, Paper III.), ploidy-heterogeneous populations are very common in others, maintained by free mating interactions and the absence of reproductive isolation among cytotypes (e.g. Pilosella echioides, Paper II.). The strenght and cumulative effect of various breeding barriers (both pre- or post- zygotic) govern the position of a particular multi-ploidy complex between these two extremes and co-determine the type of cytotype co-existence in its mixed- ploidy populations. Despite the fact that the number of studies revealing cytotype co-existence has been increasing rapidly, evolutionary background and consequences of such co-...
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Watermilfoils (Myriophyllum) in the central Europe
Hrdinová, Magdalena ; Trávníček, Pavel (advisor) ; Prančl, Jan (referee)
Genus Myriophyllum L. (watermilfoil) belongs to one of the most species-rich genera within Haloragaceae (Saxifragales). It includes three invasive species, which are of major concern - European M. spicatum L., North American M. heterophyllum MICHX. and South American M. aquaticum (VELL.) VERDC. All of them occur in Central Europe as well as native M. verticillatum L. and M. alterniflorum DC. lacking more significant invasive growth up to now. It is not only its invasivness that makes genus Myriophyllum so fascinating. It also displays extremely high phenotypic plasticity which is accompanied by determination difficulties. Moreover, recent research indicates that Myriophyllum tends to hybridize producing more invasive hybrids than parental taxa. Such traits pose a formidable challenge to scientists to deal with possible future invasive growth of non-indigenous Myriophyllum species in Central Europe. Therefore, thorough study of factors influencing evolution success of plants should be conducted. One of the key factors seems to be polyploidy. Research into polyploidy offers a new approach to watermilfoil issues. Additionally, according to preparatory study all native Central European Myriophyllum species can be easily distinguished by flow cytometry. That enables to study polyploidy in an...
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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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Ecological and evolutionary processes in primary contact zone of cytotypes of Knautia arvensis agg.
Hanzl, Martin ; Urfus, Tomáš (referee) ; Kolář, Filip (advisor)
Genome duplication events have played a crucial role in plant evolution. According to recent estimates, nearly all the angiosperms are ancient polyploids. However, establishment of new polyploid lineages within diploid populations seemed to be very unlikely, based on theoretical analyses. Reproductive interactions between the cytotypes (so-called "minority cytotype exclusion") and resource competition might eventually lead to polyploid extinction. On the other hand, the whole variety of factors may compensate both processes under natural conditions (e.g. autogamy, assorative mating, spatial separation of cytotypes). Polyploid establishment in sympatry with diploid progenitor might thus not be as restricted, as previously thought. Subsequent cytotype coexistence may represent a stable equilibrium, or just a transition leading to extinction of one chromosomal race. It is usually almost impossible to discriminate between these alternatives. Polyploid range expansions are usually accompanied by competitive exclusion of diploid cytotype or colonization of new areas and habitats. When two cytological races meet, zones of contact are often formed. Contact zones could be divided into primary and secondary ones. Primary contact zones arise as a consequence of new polyploid emergence within the progenitor's...
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Application for the Data Processing in the Area of Evolutionary Biology
Radakovič, Lukáš ; Burgetová, Ivana (referee) ; Očenášek, Pavel (advisor)
This Bachelor’s thesis describes the design and implementation of the application that has the task to verify the accuracy of the algorithm. Purpose of the algorithm is to analyze mechanisms used in the creation of the phylogenetic tree. The application allows users to specify different parameters of phylogenetic tree, its generation and subsequent analysis using an algorithm. Results of the analysis are written to the output file, giving the user the option of setting file path. Studied algorithm correctly estimates the participation of specific mechanism in the tree formation. Estimates of the absolute and relative share of changes in chromosome number and genome size are less than accurate results.
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Taxonomic study of the Eurasian taxa of Tortula muralis (Pottiaceae, Musci) complex
KOŠNAR, Jiří
The thesis aims at clarifying the taxonomic difficulties in the Tortula muralis complex. For the first time, the group was studied by means of morphometric analysis, ploidy level assessment by flow cytometry, and molecular analysis based on sequencing of ITS region of nuclear ribosomal DNA. Morphometric and cytometric studies found only two well distinguished groups within the complex. These groups corresponded to the markedly variable species T. muralis and to the rather uniform species T. lingulata. Variability in ITS sequences suggested extensive gene flow among some of traditional morphologically defined taxa of the complex. Multiple polytopic autopolyploid origin of polyploids was revealed in some taxa. Changes in taxonomic conception of T. muralis complex were proposed in order to reflect structure of morphological, karyological, and DNA variability in the group. Natural hybridization is probably an important evolutionary mechanism that generated morphological diversity and taxonomic complexity in the mosses of T. muralis complex.
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