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Interspecific hybridization between Pulsatilla pratensis and P. patens
Krejčová, Nikol ; Suda, Jan (advisor) ; Kaplan, Zdeněk (referee)
This thesis deals with interspecific hybridization in sympatric populations of Pulsatilla patens and P. pratensis. The key aim was to assess karyological and phenotypic variation in the study group. DNA flow cytometry revealed three non-overlapping groups of genome sizes, corresponding to P. patens, P. × hackelii and P. pratensis. The frequency of interspecific hybridization was low, accounting to approx. 3% of analyzed plants. Morphometric analyses identified a set a reliable species-specific characters, including number of divisions the leaf, length of petiole the part of leaf, number of smaller parts of leaf and colour of blossom. Although the majority of hybrid individuals flowered and set fruits, their fertility was reduced considerably. The threat from interspecific hybridization to parental species is therefore rather low.
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Interspecific hybridization between Pulsatilla pratensis and P. patens
Krejčová, Nikol ; Suda, Jan (advisor) ; Kaplan, Zdeněk (referee)
This thesis deals with interspecific hybridization in sympatric populations of Pulsatilla patens and P. pratensis. The key aim was to assess karyological and phenotypic variation in the study group. DNA flow cytometry revealed three non-overlapping groups of genome sizes, corresponding to P. patens, P. × hackelii and P. pratensis. The frequency of interspecific hybridization was low, accounting to approx. 3% of analyzed plants. Morphometric analyses identified a set a reliable species-specific characters, including number of divisions the leaf, length of petiole the part of leaf, number of smaller parts of leaf and colour of blossom. Although the majority of hybrid individuals flowered and set fruits, their fertility was reduced considerably. The threat from interspecific hybridization to parental species is therefore rather low.
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Homogenization of bird communities
Krsová, Magdalena ; Reif, Jiří (advisor) ; Sedláček, Ondřej (referee)
Biotic homogenization is characterized as a process by which means species invasions and extinctions increase the genetic, taxonomic or functional similarity among ecological communities and this process is associated with modern biodiversity crisis. The most prominent patterns of recent homogenization of species composition in avian communities are loss of native species and their replacement by non-native species, expanding habitat generalists at the expense of native and more specialized species. As a result, increases in local or alpha-diversity typically occur at the expense of decreased beta-diversity or increased community similarity among regions. These patterns are probably caused by introduction non-native species, urbanization, landscape fragmentation and disturbance. These results suggest that conservation effort should focus on protection of unique habitats where ecologically specialised species occur. Further research in this area could provide better basis for generation of simulation models aimed to predicting changes in community composition.
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