Butterfly family Lycaenidae is cosmopolitan. Some species of the family are common in the Czech Republic, but some are at the risk of extinction, which is caused either by lack of habitat or host plant deficiency. Among the most endangered species in the Czech Republic are the damon blue (Polyommatus damon (Denis a Schiffermüller, 1775)) and the turquoise blue (Polyommatus dorylas (Denis a Schiffermüller, 1775)). This thesis aims to review the biology of both species, causes of threat and possibilities of their practical conservation, and to describe genetic variability of Czech populations of two critically endangered Lycenids, the damon blue and the turquoise blue, and to compare them with European populations for potential import of alien individuals to Czech populations. Genetic assignment is important for possible reintroduction or revitalization of Czech populations from foreign sources. I detected in this thesis that the damon blue has more genetic variability than the turquoise blue and this pattern is not only geographical. I assume that Czech populations of both species experienced bottleneck and are under genetic drift. Furthermore, the Central European individuals genetically differ from Southern European and Baltic samples, and the number of haplotypes is high in Central Europe. The current distribution is not caused by colonization after the last glacial period. According to the results, it is appropriate to protect all current populations separately, rather than supplement them from other sources, because they can be genetically different. Finally, I discuss the management planned for the two species in the Czech Republic and connect it to my results.

Plants can interact with many different organisms on many trophic levels in their life. In this thesis I investigated how three biotic inertactions, powdery mildew infection, caused by Podosphaera ferruginea, predispersal seed predation by Dusky Large Blue (Phengaris nausithous) and Scarce Large Blue (P. teleius) and deer grazing affect life cycle and population biology of the Great Burnet (Sanguisorba officinalis L.). I also analysed their preferences of environmental conditions. Most of studied plant populations growth rates (λ) were lower than 1 and population decreased, but quite surprisingly for more populations vegetative reproduction was more important than reproduction by seeds. All intraction mentioned above affects more generative reproduction, and thus their influence on Great Burnet population dynamics is low, even with modelled maximal possible effect. Environment conditions analysis showed that powdery mildew occurs on sites with more flowering individuals, where spreading is very easy, butterflies preferred high, well noticeable flower heads grown high above other vegetation and host ant presence. For host ants' presence model locality was only significant variable.