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Evolution of the genus Arabidopsis in its centre of diversity
Šrámková, Gabriela
A prerequisite for addressing general questions concerning the evolution of intraspecific variability in space and time is the knowledge of the distribution of variability within the species' range. The development of molecular methods has been a major step forward, allowing various evolutionary questions to be addressed using natural populations of model species and their close relatives. Although wild relatives of Arabidopsis thaliana have long been in the focus of plant evolutionary biologists and molecular geneticists, the patterns of genetic diversity and phenotypic variation in their natural populations are often overlooked. The present work focuses on some of the most studied model species in the Brassicaceae family, Arabidopsis halleri and the complex of A. arenosa, whose members are widely used to study ecology, physiology and evolution as well as the molecular basis of phytoremediation and parallel adaptation. The study aimed to determine intraspecific variation at the ploidy level, to reveal phylogenetic relationships and the spatial distribution of genetic diversity across the range, and to propose a new taxonomic concept based on the detected intraspecific genotypic and phenotypic variation. In order to accomplish this goal, we used DNA flow cytometry, several molecular methods (AFLP,...
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Evolution of the genus Arabidopsis in its centre of diversity
Šrámková, Gabriela ; Marhold, Karol (advisor) ; Greimler, Josef (referee) ; Mártonfi, Pavol (referee)
A prerequisite for addressing general questions concerning the evolution of intraspecific variability in space and time is the knowledge of the distribution of variability within the species' range. The development of molecular methods has been a major step forward, allowing various evolutionary questions to be addressed using natural populations of model species and their close relatives. Although wild relatives of Arabidopsis thaliana have long been in the focus of plant evolutionary biologists and molecular geneticists, the patterns of genetic diversity and phenotypic variation in their natural populations are often overlooked. The present work focuses on some of the most studied model species in the Brassicaceae family, Arabidopsis halleri and the complex of A. arenosa, whose members are widely used to study ecology, physiology and evolution as well as the molecular basis of phytoremediation and parallel adaptation. The study aimed to determine intraspecific variation at the ploidy level, to reveal phylogenetic relationships and the spatial distribution of genetic diversity across the range, and to propose a new taxonomic concept based on the detected intraspecific genotypic and phenotypic variation. In order to accomplish this goal, we used DNA flow cytometry, several molecular methods (AFLP,...
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Polyploidy in natural populations of Arabidopsis
Bayerová, Jana ; Kolář, Filip (advisor) ; Čertner, Martin (referee)
This thesis deals with polyploidy in natural populations in the genus Arabidopsis. It summarizes information about the relatives of Arabidopsis thaliana, a prominent model organism for research on genetics and plant physiology. Literature shows that polyploidy affects ecological, climate and soil requirements, as well as mating system of the plants in genus Arabidopsis. Most of the published studies is focused on the study of artificial polyploid hybrids created by crossing experiments - especially with the Arabidopsis thaliana. In contrast, my thesis deals with the natural polyploids observed within the genus. In particular, I focus on the nearly unstudied di- polyploid complex of high-altitude populations of Arabidopsis arenosa in the Tatra Mountains. This complex represents a unique model system for studying the effects of polyploidization in the wild - thanks to the high morphological and ecological diversity of the hybrids, and to the relative genetic similarity of the parental populations. Key words: allopolyploid, Arabidopsis, Arabidopsis arenosa, autopolyploid, hybridization, polyploidization, Tatry
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Autopolyploids: particularly hopeful monsters
Holcová, Magdalena ; Schmickl, Roswitha Elisabeth (advisor) ; Mráz, Patrik (referee)
Autopolyploidy, genome duplication per se, is a severe mutation which presents both great challenge and great opportunity for the species which has undergone it. First, a whole series of initial challenges has to be overcome, e.g., establishment within diploid parental population, proper functioning of the cell with doubled genetic information and restoration of proper mitosis and meiosis. The population genetic changes can become beneficial afterwards as the two times higher effective population size and polysomic inheritance increase heterozygosity and genetic variability within the new polyploid lineage. It also reduces negative impacts of genetic drift and inbreeding depression. In evolutionary context, having two genomes allows selection to be more relaxed, thus genes can quickly diversify into alleles with new function or sub-function. To better understand the molecular mechanisms of selection on a population level, I choose example of meiosis genes evolution in a polyploid Arabidopsis arenosa (Brassicaceae) species complex. This only diploid-autotetraploid member of the plant leading model genus Arabidopsis provides an ideal system for addressing general questions on the triggers and consequences of genome duplication in plants. In contrast to other members of the genus, A. arenosa remained...
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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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