| Summary: | Polyploidization and hybridization are the main microevolutionary processes, which take place within pteridophytes and dominantly participate in their variability and further speciation. Reproductive strategies are also related with above mentioned processes, especially various type of apomictic reproduction, which play an important role within ferns (compared to Angiosperms). Polyploidization and hybridization take part in Cystopteris fragilis (L.) Bernh. (common fragile fern) and both are also recently participating in origin of new cytotype (mirrored by enormous proportion of mixed populations consisting off tetraploids to octoploids). The main goal of this diploma thesis is cytotype structure of particular stages within the life cycle of common fragile fern with evaluation of sporogenesis (viability, exospore length and number of spores), together with testing reproductive strategies of individual cytotype using flow cytometry. Moreover, an experimental hybridization is supplementing above mentioned aims of the diploma thesis. The main sources of variability seem to be restricted to tetraploids and pentaploids, whereas hexaploids produce only uniform progeny. Tetraploids form both diploid reduced and tetraploid unreduced spores (but only 1,97 % of total amount of spores). Pentaploids have variable...
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