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Anthropogenic hybridization between selected cultivated and wild relatives from the genus Malus (Rosaceae)
Orlovská, Lívia ; Slovák, Marek (advisor) ; Chrtek, Jindřich (referee)
Hybridization is an important driver of plant evolution, but it can also pose a threat to the genetic integrity of species. A specific case is gene flow induced by human activity, or "anthropogenic hybridization." In addition to theoretical knowledge about hybridization, introgression, and the protection of genetic diversity, this thesis presents its importance and impacts using the example of a model system from the Malus genus. By analyzing the available studies on the subject, I compare and evaluate the state of European populations of the wild species Malus sylvestris, which is subject to hybridization and introgression mainly with the cultivated species Malus domestica. The data indicate a common hybridization between these species to varying degrees, with up to 37 % of hybrid individuals in the population. The human effect is significant, particularly through the intensification of landscape utilization, which results in more frequent secondary contacts between species and subsequent gene flow. However, the available studies about hybridization between these species are mostly local, and a comprehensive view of the issue is lacking. Indeed, in the Czech Republic and Slovakia, there are presently no comparable empirical investigations utilizing genetic data. Overall, it implies that it is...
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Taxonomy and variability of selected Sorbus taxa
LEPŠÍ, Martin
This thesis is a biosystematic study focusing on the taxonomy and variability of selected taxa of the genus Sorbus, one of the most diverse and taxonomically complicated plant groups in Europe. Classical and modern biosystematic methods - comparative study, chromosome counting, analysis of nuclear microsatellite markers, flow cytometry, and traditional multivariate and outline morphometric analyses were used to assess the morphological, karyological and genetic variability of the genus. The final synthesis of these approaches led to the description of several new taxa (species, hybrids and a subgenus) and the correction of several taxonomic misinterpretations. To reveal ongoing evolutionary processes responsible for the generation of the observed variability, the reproductive modes of 42 Sorbus taxa were examined using flow-cytometric seed and pollen screens. Apart from revealing major trends, the study estimates the frequency of rare events and provides several novel conclusions that are relevant both specifically to Sorbus/Rosaceae and to apomixis in general.
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