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Reproductive isolation between diploid and tetraploid cytotype of Vicia cracca and possibilities of evolution of this aggregate
Vlčková, Zuzana ; Münzbergová, Zuzana (advisor) ; Mráz, Patrik (referee)
Master thesis investigates reproductive barriers in diploid-polyploid complex of Vicia cracca. Complex with basic chromosome number x=7 consists of diploid (2x=14), tetraploid (4x=28) and rare triploid (3x=21) cytotype. I studied prereproductive barriers between diploid and tetraploid cytotype: phenology of flowering, pollinators' behavior (preference of spieces of pollinators to cytotypes, sequence of visited cytotypes), variables, that could explain pollinators' behavior (amount of nectar as the main reward, size and amount of pollen grains as a potentional reward). To find out how strong the triploid block is I analyzed ploidy of seeds and seedlings from mixed-ploidy population. The habitat isolation showed up to be the strongest reproductive barrier. Pollinator's behavior meaningfully contributes to isolation, phenology of flowering contributes only minimally. Index expressing rate of prereproductive barriers is 0,956. Pollinator Bombus pascuorum visited on one locality preferably tetraploid plants and Andrena sp. preferred diploid plants. Even though tetraploid plants produce more nectar, no other analysis showed pollinators' preference to tetraploid plants. I prepared one squash of diploid V. cracca using method of in situ hybridization. This method needs to be optimilized for the studied taxon.
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On the Origin of Chenopodium album by Means of Hybridization
Kondrysová, Eva ; Mandák, Bohumil (advisor) ; Mráz, Patrik (referee)
Diploma thesis deals with genetic variability and evolutionary relationships among selected species of the group Chenopodium album and is especially focused on the origin of hexaploid species C. album in the Czech Republic. The main aim of the study was detection of putative recent emergence of hexaploid C. album s. str. in mixed populations of diploid (C. ficifolium and C. suecicum) and tetraploid (C. strictum and C. striatiforme) species. To assess phylogenetical relationships I performed an analysis of nuclear microsatellite loci, that are suitable for detection parental lines within polyploid species. As long as microsatellite primers have been developed for studied group, therefore they had to be cross-amplified from closely related species C. quinoa. Three PCR multiplexes were assembled by cross-amplification of microsatellite primers. These PCR multiplexes were tested on representative sample sets to estimate genetic variability of individual microsatellite loci. A total of 911 individuals were analyzed from five localities from the Czech Republic. The results of analyses revealed (1) high interspecific differentiation, (2) gene flow among species of the same ploidy levels, (3) presence of hybrids among diploid species of C. ficifolium and C. suecium as well as among tetraploid species C. strictum...
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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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Population cytotype structure and phenotypic variation of Campanula moravica
Šemberová, Kristýna ; Suda, Jan (advisor) ; Mráz, Patrik (referee)
Polyploidisation plays a major role in plant evolution. It can also cause taxonomic complexities as morphological differences are often blurred in higher ploidy levels. One of the taxonomically-intrigued groups of Central Europe is C. rotundifolia agg. Three ploidy- heterogeneous species are traditionally recognized in the Czech Republic: C. gentilis (2x, 4x), C. rotundifolia (2x, 4x) and C. moravica (4x, 6x). The thesis examines karyological and phenotypic variation of C. moravica, in the centre of its distribution (the Czech Republic and Slovakia). With the aid of modern biosystematics tools (DNA flow cytometry, multivariate morphometrics), marked discrepancies were revealed between published data and actual cytotype distribution pattern and morphological variation. In contrast to literature records, cytotype distribution in C. moravica is largely parapatric, with hexaploids occurring in Pannonian basin and tetraploids in Central and Eastern Slovakia. The type population of presumed tetraploids turned out to be hexaploid. The coexistence of one majority (4x) and six minority cytotypes (2x, 3x, 5x, 6x, 8x, 9x) was found in one population in central Slovakia and represent the most salient case of ploidy coexistence ever reported. Multivariate morphometrics showed that species identification on the...
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