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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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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Chumová, Zuzana (referee)
Genus Sorbus is a very complex group of vascular plants. Various genetic lineages which can be fixed by apomixis are driven by interspecific hybridisation and polyploidy. Species from S. aria agg. have the highest variation probably due to an extra mechanism - introgressive hybridisation. There are several concepts of the aggregate which are usually based on three main species: S. aria, S. umbellatta and S. graeca. Therefore, new microspecies are derived by genome doubling and hybridisation between the main species. Units of the aggregate are assessed differently as the distinction of taxa is very complicated due to the overlap of the morphological variability. The aggregate itself can be sometimes considered as a category for species of uncertain origin or identification. Four species from S. aria agg. occur in the Czech Republic. In addition, the conclusion offers questions that will be addressed in the master's thesis.
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Is there any influence of ecological gradient on the introgression and its evolutionary consequences in the genus Arabidopsis?
Hojka, Jakub ; Marhold, Karol (advisor) ; Mráz, Patrik (referee)
1 Hybridization, introgression and polyploidy, especially in their combination, belong to the most important speciation processes in vascular plants. Athough basic features of these processes are generally well known, their cases in particular groups of plants and concrete cases differ a lot and their studies often bring interesting results. In the genus Arabidopsis several cases of combined hybrid and polyploid speciation are known (e.g. A. kamchatica, A. suecica) and there are also cases where we expect introgressive hybridization (e.g. between A. arenosa and A. petraea). The aim of the bachelor thesis is an evaluation of known cases of homo- and heteroploid introgressive hybridization and hybrid speciation in the genus Arabidopsis in the context of similar cases in the family Brassicaceae and perhaps also other families of vascular plants. Next aim is to design method of detailed evaluation of the introgressive zone of A. arenosa and A. petraea (= A. lyrata subsp. petraea) in Central Europe using mophological, cytometric and molecular evidence as well as ecological parameters of studied localities. Set of morphological characters will be tested on the currently available material of A. arenosa that is cultivated at CEITEC Brno as part of the finalised GACR project.
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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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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Chumová, Zuzana (referee)
Genus Sorbus is a very complex group of vascular plants. Various genetic lineages which can be fixed by apomixis are driven by interspecific hybridisation and polyploidy. Species from S. aria agg. have the highest variation probably due to an extra mechanism - introgressive hybridisation. There are several concepts of the aggregate which are usually based on three main species: S. aria, S. umbellatta and S. graeca. Therefore, new microspecies are derived by genome doubling and hybridisation between the main species. Units of the aggregate are assessed differently as the distinction of taxa is very complicated due to the overlap of the morphological variability. The aggregate itself can be sometimes considered as a category for species of uncertain origin or identification. Four species from S. aria agg. occur in the Czech Republic. In addition, the conclusion offers questions that will be addressed in the master's thesis.
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