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Factors affecting reproductive success of deceptive orchids
Steffelová, Michaela ; Kindlmann, Pavel (advisor) ; Štípková, Zuzana (referee)
This thesis focuses on the study of the reproductive biology of nectarless orchids, which are characterized by the absence of nectar, resulting in pollinators not receiving a reward for pollen transfer. This factor can have a significant impact on the reproductive success of these plants. Furthermore, the reproductive success of nectarless orchids is influenced by other factors, such as inflorescence size, plant height, species, flowering time, population characteristics, or climatic and spatial conditions. This study examines nectarless orchids Anacamptis morio, Dactylorhiza majalis and Anacamptis pyramidalis as model species and measure the above-mentioned factors on the plants. The main findings of this study are: (i) The number of conspecific neighbors has almost no influence on reproductive success. (ii) There is a parabolic dependence between reproductive success and the number of flowers in the species A. morio and D. majalis, while in the species A. pyramidalis, this dependence is linear. The parabolic dependence of reproductive success on the number of flowers, predicted by the theoretical model presented here, was found in only one other study. The more frequently found linear dependence between these variables, found in this study only in the species A. pyramidalis, may be due to the...
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Distribution of population sizes within different orchid metapopulations
Švecová, Magdaléna ; Kindlmann, Pavel (advisor) ; Štípková, Zuzana (referee)
Orchids, as one of the most species-rich families in the world, are known for their specific symbiotic relationships with other organisms and can therefore be referred to as indicators of the state of vegetation. Studying orchids as metapopulations allows us to better estimate the level of threat of individual orchid species. The traditional metapopulation model assumes a metapopulation consisting of sub-populations, where individual populations are connected by migration, and colonization of new and recolonization of existing localities occurs. Orchids, on the other hand, show a different behavior. Their seeds are spread passively by wind, and the colonization of new habitats is therefore rather random. Therefore, a new model would be suitable for the study of orchids, which should include information on the size of the population of a given orchid species, taking into account the region in which they occur. The metapopulation is also influenced by the temperature and amount of precipitation before the flowering period, the possibility of individual sterility or dormancy, and last but not least, the quality of management on the site. These variables should be included in a new metapopulation model that could better describe changes in orchid metapopulations. This thesis provides the basis for a...
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Determinants of orchid species diversity
Štípková, Zuzana ; Kindlmann, Pavel (advisor) ; Kull, Tiiu (referee) ; Whigham, Dennis (referee)
Natural environment has been significantly altered by human activity in past few decades. There is an evidence that we are now facing the sixth mass extinction and suitable areas for species are getting smaller. Therefore, many species of plants and animals are experiencing strong population decline and some of them even became extinct. We focused our attention on orchids because their distribution expresses one of the highest declines among all plant families. In this thesis, we investigated species richness and distribution patterns of orchids, the rate and causes of their decrease and extinction, and factors influencing their occurrence in the Czech Republic and Greece. In the majority of the presented papers, we used a dataset based on the database of the Nature Conservation Agency of the Czech Republic that includes more than 115 000 of orchid records in the country. We also analysed the patterns in the six different phytogeographical regions in the Czech Republic that differ in altitude and the composition of local flora. The key findings are as follows: The specialized pollination strategy of orchids, as well as type of rooting systems, both in the Czech Republic and in Greece, play a role in the distribution patterns of orchids in the two countries (Papers I, II and VI). Moreover, the...
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