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Genome duplication in Stellaria genus - the more, the merrier? Link between ploidy levels and sexual polymorphism.
Krtilová, Eliška ; Slovák, Marek (advisor) ; Prančl, Jan (referee)
Polyploidization in angiosperms, a well-documented phenomenon, often correlates with a diversity of reproductive strategies, including sexual polymorphism, impacting their evolution and expression. This relationship is particularly intriguing in high polyploids, where the interaction can be complex yet largely enigmatic. We investigated the connection between high polyploidy and sexual polymorphism in Stellaria palustris (Caryophylaceae), a species complex with exceptionally high levels of polyploidy exceeding decaploids and reportedly exhibiting variable sexual expression. To broaden our analysis, we included its relatives, diploid-tetraploid S. graminea and diploid S. longifolia. Our study focused on Central and Northern Europe, utilizing various methodological approaches, including genome size estimation, chromosome counting, genetic analyses based on Sanger sequencing, and evaluating floral organ variability and sexual expression. Major hypotheses examined associations between ploidy level and latitude, as well as ploidy level and sexual polymorphisms. Chromosome counts of S. palustris ranged from 2x = 154 - 208, corresponding to 2n=12x, 14x, and 16x, while for S. graminea and S. longifolia, we confirmed their originally known ploidies. Although chromosome counts did not unambiguously reflect...
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Influence of temperature on the shifts in sexuality of gynodioecious species Stellaria graminea (Caryophyllaceae)
Krtilová, Eliška ; Slovák, Marek (advisor) ; Macková, Lenka (referee)
Sexual polymorphisms represent an essential phenomenon in the evolution and reproduction of flowering plants. One of the types of sexual polymorphisms is gynodioecy, a phenomenon in which a plant species forms morphologically and functionally hermaphrodite, but also female individuals. However, the stability of sexuality expression of both types can be influenced by environmental factors, what might, finally, lead to shifts in sexuality (from hermaphrodites to females and vice versa). These changes are often very dynamic and can have a significant positive but also negative effect on genetic variability and overall fitness of the species. The main content of the work will be the elaboration of a research on the given topic which will contain chapters focused on sexual polymorphisms in flowering plants, gynodioecy, the influence of environmental factors on the lability of sexual expression and its effects on genetic variability and overall survival of species. An important part will also be the inference of the potential impact of climate change on fitness and survival of sexually polymorphic plant species. The theoretical part of the work will also focus on the model species selected for subsequent master's thesis, specifically Stellaria graminea. It is a perennial polyploid species inhabiting the...
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