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Species and cytotype diversity of invasive Symphyotrichum species in Central Europe
Varvažovská, Adéla ; Slovák, Marek (advisor) ; Hodálová, Iva (referee)
The cytotypic variability of Aster species of the genus Symphyotrichum is relatively well-explored within the territory of North America, where this species originates. Unfortunately, in Europe, where Asters were originally introduced as ornamental plants, they have received limited attention in terms of their overall as well as cytotypic variability. The number of publications and data concerning cytotypic variability and karyology in Europe is very limited, with some reporting the occurrence of several species and higher ploidy level species complexes. Asters naturalize in many places, capable of reproducing both vegetatively and generatively, and primarily colonize habitats disturbed by human activities. As a result, they have been classified as invasive plant species. From a biosystematic perspective, Asters constitute a highly complex group due to their high morphological and karyological variability. This situation is further complicated by the phenomenon of polyploidy and intense interspecific and intraspecific hybridization. These factors contribute to the challenging task of identifying individuals and populations and assigning them to specific taxa. The aim of this thesis was to clarify the cytotypic variability of wild-growing Aster species of the genus Symphyotrichum (Asteraceae) in the...
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The cytotype diversity and population demography of invasive aster from Symphyotrichum lanceolatum a S. novi-belgii groups in Central Europe.
Varvažovská, Adéla ; Slovák, Marek (advisor) ; Chrtek, Jindřich (referee)
Asters from Symphyotrichum lanceolatum and S. novi-belgii a species complexes are native to North America from where they were imported to Europe as ornamental plants during the 19th century. They were naturalized and later became invasive in the humid habitats along rivers and lakes. Both species groups are karyologically and morphologically highly variable what is reflected in their complex taxonomy. A crucial role in the formation of their intricated diversity play inter- and intraspecies hybridization, polyploid evolution as well as phenotypic plasticity. The biological and ecological diversity of Asters was thoroughly studied in their natural environment in North America, however only little is known about their variability in their new, invaded European habitats. Numerous polyploid cytotypes were reported from their native distribution range in North America, however, only a single cytogeographic study in Europe has been published to date. The outcomes of this study accompanied by occasional chromosome counts indicated the existence of higher ploidy levels only. Specifically hexaploid and octoploid cytotype was reported for S. lanceolatus while hexaploids in S. novi-belgii. The problem of the karyological variability of these taxa in Europe deserves attention and further research. Key words:...
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