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Biogeography of the herpetofauna of the Aegean Islands
Sýkorová, Marta ; Šmíd, Jiří (advisor) ; Papežík, Petr (referee)
In the last thirty years, the biogeography of the herpetofauna of the Aegean Sea has been the subject of thorough research. In evolutionary biology, islands are considered to be model ecosystems. Morphological, physiological and behavioral changes in some species can be observed on them. These changes are described as so-called "island syndromes". The occurrence of these syndromes depends on the size of the island, its distance from the mainland and the age of the island as well as on population density, availability of resources and presence of predators. The specific manifestations of these syndromes in reptiles of the Aegean islands are: the occurrence of endemism, gigantism and dwarfism, color changes, more frequent tail autotomy, cannibalism and food specialization. Most of these changes are described in lizards of the Podarcis genus, especially on Podarcis erhardii, as it is the most widespread reptile in this area. The second very widespread and therefore often researched reptile is Mediodactylus kotschyi. Changes often take place on small islands, so individuals tend to be compared with members of the same species from a larger island or mainland. The number of endemic species is significantly higher on islands that are longer separated from the mainland. The existence of gigantism and...
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Plant strategies in belowground competition - insight through game theory
Smyčka, Jan ; Weiser, Martin (advisor) ; Šmilauer, Petr (referee)
In recent decades, it was shown that belowground competition for some plants may take form of the tragedy of the commons (TOC). In these plants, the competing neighbours invest more in root systems than would be appropriate for optimal nutrient uptake for the group and also more than they do when grown alone. However, there is also strong evidence that other species do not follow TOC, and tailor their root system to best nutrient exploitation irrespectively of competitor presence. The root investment strategy of these plants should correspond to the ideal free distribution (IFD). In my thesis I focus on two aspects: I use game theoretical models to explore, whether those strategies can coexist within species and also whether different species can coexist if they have different strategy. From this model I draw predictions, which I test by meta-analysis. Using Agrostis stolonifera as a model, I test assumptions on nutrient and neighbour perception, which underlie TOC and IFD models. I show that according to mathematical models, those two strategies can coexist in different species in a community, but cannot coexist within a species. Within a species, the TOC strategy should always dominate, once it appears. This can be extrapolated to macroevolutionary scale - once TOC occurs in certain clade, it should...
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