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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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Risk assessment of interspecific hybridization between endemic Campanula bohemica and widespread C. rotundifolia s.l.
Hanušová, Kateřina ; Suda, Jan (advisor) ; Krahulec, František (referee)
The thesis deals with phenotypic, ploidy and genetic variation of two Campanula species occurring in the Krkonoše Mts., namely the endemic C. bohemica and widespread C. rotundifolia subsp. rotundifolia. For comparative purposes subspecies sudetica of the latter species was also included. The main aim was to get insight into population structure and assess the threat of interspecific hybridization to the survival of the endemic bluebell. Flow cytometry, distance-based morphometrics and molecular analysis were used to address these questions. Three distinct groups of fluorescence intensities were revealed by flow cytometry, corresponding to DNA diploids, tetraploids and pentaploids. While diploids morphologically matched the nominate subspecies of C. rotundifolia, tetraploids corresponded either to C. rotundifolia subsp. sudetica or C. bohemica. Most populations from the Krkonoše Mts. were uniform although a sympatric growth of diploids and tetraploids was encountered in 12 populations. Only two pentaploids individuals, most likely of hybrid origin, were found, which indicated that interspecific hybridization is much less common than previously assumed. The two tetraploid taxa were distinguished by molecular markers. A combination of flow cytometry and molecular analyses thus allowed reliable...
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Current occurrence of eyebright (Euphrasia) in the Krkonoše (Giant) Mountains and the evaluation of the effect of the time of mowing
Blahník, Jan ; Krahulec, František (advisor) ; Mudrák, Ondřej (referee)
At the time the Black and Red List of the Vascular Plants of the Krkonoše (Giant) Mountains was being compiled it was found that no information was available about the distribution of eyebright (Euphrasia) or other facts concerning this hemiparasite growing in the Krkonoše. The aim of this work was to fill the gap. This was to be done by creating a GIS layer with the current distribution of eyebright in the mountains, by analysing the soils taken in places of eyebright occurrence, in neighbouring places and those closely resembling them but without eyebright. The soils were taken each time from five places in the particular locality and were analysed as a mixed sample. In all, 107 mixed soil samples were taken, of which 53 in places where eyebright occurred and in 54 similar places where eyebright was absent. Eyebright grows in places with a higher pH and it performs better in lower available phosphorus concentration. Management test was used to test the earlier time of mowing meadows containing eyebright, when a larger number of flowering eyebright occurs among the plants in comparison with the number of flowering eyebright on surfaces mown at a later time.; Management testing was carried out from June to July 2011 in six localities, with five plots in each locality, in the Eastern and Western...
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Human-driven and natural vegetation changes of the last glacial and early Holocene
Kuneš, Petr ; Pokorný, Petr (advisor) ; Krahulec, František (referee) ; Ammann, Brigitta (referee)
Conclusions The main conclusions, specific to each research topic, have been mentioned in appropriate chapter. To summarize, the thesis brings new original data and reinterprets existing pollen assemblages of the last glacial and early Holocene in central Europe. It also deals with analysis of the analogues and with vegetation-pollen relationship when interpreting past vegetation. The study of analogue environment brought several important conclusions. A considerably tight relationship was found between the composition of pollen spectra and climate characteristics in southern Siberian analogue landscape. This means that past climatic conditions can be reasonably predicted by the fossil pollen spectra. There were found the best pollen predictors (such as Pinus sylvestris, P.cembra, Betula alba, Artemisia, Graminae) and 300 m distance around the sampling point as the best factors explaining vegetation type. Vegetation was interpreted for the last glacial and the beginning of the Holocene in the light of new palaeobotanical finds and according to modern approaches. Occurrence of some tree species during various stages of the last glacial were confirmed, however, local discrepancies in vegetation and climate were also highly important. This supports strong gradient in increasing treelessvegetation from the...
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Natural hybridization between two allopolyploid wheatgrasses Elytrigia intermedia and E.repens (Poaceae, Triticeae)
Mahelka, Václav ; Krahulec, František (advisor) ; Bureš, Petr (referee) ; Blattner, Frank (referee)
Aims of the Thesis The thesis is part of an ongoing project focused on hybridization in the wheat (Triticum aestivum)Elytrigia intermedia-E. repens species complex. This complex represents a real model of cropweed (wild relative) system with potential gene flow. The aim ofthe project is to detectand possibly to evaluate the frequencyof geneflow from wheat into its wild relative,E. intermedia.Such study could provide a crucial background for potential risk assessmentof the release of genetically modified wheat into the environment. Wheat is often crossedwith E intermedia in order to transfer some desirabletraits of the wild grass into the wheat genome. Such hybridization is routinely performed under laboratory conditions; however, it has not yet been observed under natural conditions. Since E intermedia crosseswith E repens, it may serve as a bridge species for gene flow from wheat into the weedy E. repens. Knowledge of the frequency of hybridization between both Elytrigia congeners with its consequencesis thus of high interestand is the main objective of the thesis.The aims of the thesis can be summarizedas follows: (1) to eva|uatecýological variability of Elytrigia repens and E. intermedia n natural populations in the Czech Republic; (2) to establish reliable diagnostic markers for species and hybrid...
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Natural hybridization between two allopolyploid wheatgrasses Elytrigia intermedia and E.repens (Poaceae, Triticeae)
Mahelka, Václav ; Krahulec, František (advisor) ; Bureš, Petr (referee) ; Blattner, Frank (referee)
Aims of the Thesis The thesis is part of an ongoing project focused on hybridization in the wheat (Triticum aestivum)Elytrigia intermedia-E. repens species complex. This complex represents a real model of cropweed (wild relative) system with potential gene flow. The aim ofthe project is to detectand possibly to evaluate the frequencyof geneflow from wheat into its wild relative,E. intermedia.Such study could provide a crucial background for potential risk assessmentof the release of genetically modified wheat into the environment. Wheat is often crossedwith E intermedia in order to transfer some desirabletraits of the wild grass into the wheat genome. Such hybridization is routinely performed under laboratory conditions; however, it has not yet been observed under natural conditions. Since E intermedia crosseswith E repens, it may serve as a bridge species for gene flow from wheat into the weedy E. repens. Knowledge of the frequency of hybridization between both Elytrigia congeners with its consequencesis thus of high interestand is the main objective of the thesis.The aims of the thesis can be summarizedas follows: (1) to eva|uatecýological variability of Elytrigia repens and E. intermedia n natural populations in the Czech Republic; (2) to establish reliable diagnostic markers for species and hybrid...
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Geographical parthenogenesis: evolutionary and ecological significance of apomictic reproduction in vascular plants
Hartmann, Matthias ; Mráz, Patrik (advisor) ; Dobeš, Christoph (referee) ; Krahulec, František (referee)
It has been suggested that polyploidization affects the ecological niche of a species, possibly ultimately leading to a shift in the distribution of the species, such as in geographical parthenogenesis. The phenomenon describes the wider distribution and shift of asexuals towards higher altitudes, northern latitudes and more extreme habitats when compared with their closely related sexual relatives. Several hypotheses have been proposed to explain such patterns with lacking empirical evidence because investigations rather focused on single hypotheses, which were rather tested several times independently on multiple organisms than vice versa. Therefore, the present study aimed to tackle the phenomenon of geographical parthenogenesis from multiple angles, i.e. testing several hypotheses simultaneously using Hieracium alpinum as a model system. In the arcto-alpine Asteraceae H. alpinum sexually reproducing diploid individuals occur in a small isolated area in the Eastern and Southern Carpathians, while apomictically reproducing, i.e. asexual reproduction via seeds, triploid plants occupy the remaining and much larger part of the range from the Balkans to the arctic parts of Europe. This implies that asexual triploids have had some fitness / colonization advantage(s), leading to a replacement of sexual diploids...
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The role of hybridization in plant evolution - using different methods for detecting plants of hybrid origin in the Elytrigia repens - Elytrigia intermedia hybrid complex
Paštová, Ladislava ; Krahulec, František (advisor) ; Kovařík, Aleš (referee) ; Blattner, Frank (referee)
Hybridization is an important phenomenon in plant evolution because it is one of the sources of new genetic variability. Hybridization is the merging of genomes of formerly isolated evolutionary lineages. In many taxonomic groups, the detection of plants of hybrid origin is challenging. A wide spectrum of methods for their detection has been employed since the beginning of botanical research. The introduction of genomic in situ hybridization has had a great impact on the study plants of hybrid origin. This molecular cytogenetic approach allows to reveal the genomic contributions of particular parental species to hybrid taxa. The tribe Triticeae is a prime example of a group whose present-day diversity has been strongly influenced by hybridization (together with polyploidy). The majority of its species are allopolyploids resulting from frequent interspecific and intergeneric hybridization. The structure of relationships within the tribe is therefore highly reticulate. This thesis includes three papers dealing with the hybrid complex of Elytrigia repens - E. ×mucronata - E. intermedia: (1) The representatives of this hybrid complex are morphologically poorly differentiated, and only two morphological characters are used to their distinguishing. Among anatomical characters on the leaf blade, some...
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Importance of hybridization in genus Sorbus evolution
Ondříčková, Klára ; Urfus, Tomáš (advisor) ; Krahulec, František (referee)
From a lot of reason it is really complicated to evaluate biosystematicaly the facultative apomictic groups like a Pilosella, Rubus or Sorbus. How to define the taxons is complicated because of still ongoing microevolutional processes such as inter- specific hybridization, polyploidization and apomixis. Due to these procedures there appear speciations of many genetically different lineages that are separate in the repro- duction. They evince an immense variability on the morphological level. The apomixis itself can be modified a lot and it is combined with other reproductive strategies usually. It was possible to put the hybridization experiments into practice thanks to the huge collection of mainly middle European taxons representatives from genus Sorbus, in Dendrology garden in Průhonice. The trees used for the experimental crossing, were inspected to the microsatellite analysis to specify in more detail their membership of taxons identity. The analysis of new-emerged seeds was performed by flow cytometery (Flow cytometric seed screen - FCSS) enabling very quick detection of reproductive pathways, how the seeds were formed. It has been definitely demonstrated, that the var- iability of the reproductive pathways is very wide, even between each individual cross- ing. There were detected the...
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