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Faktory ovlivňující početnost nepůvodního savčího predátora kočky domácí (Felis catus) ve středoevropské kulturní krajině a lidských sídlech.
KALENDOVÁ, Pavlína
The domestic cat is currently one of the most widespread invasive predators, which causes great losses to populations of many species. Due to its strong association with humans, individuals of this species are found on almost every continent and many islands, where it acts as a strong extinction factor. Using point counts, I surveyed the abundance of cats and bird species in the vicinity of České Budějovice and evaluated whether selected environmental factors influence the presence of domestic cats. The selected factors included site type, habitat, weather, temperature, season, and amount of vegetation at the site at the time of the inspection. The weather was only factor that had a statistically significant effect. Specifically, more cats were recorded on partly cloudy and sunny days than on bright or gloomy days. I also investigated whether the presence of the domestic cat at a given location has an effect on the number of recorded bird species or the number of individuals. According to the results, the presence of one or more cats at particular sites did not have a statistically significant effect on the number of bird species or the number of individuals.
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Why are geographic ranges of species mostly small? Causes of range size variation
Kalendová, Pavlína ; Storch, David (advisor) ; Hořák, David (referee)
Species range size is collection of all regions which the specie occupies. Every specie has different range size, the most widespread are marine species. Range size distribution is log-normal, which means that the most of species have narrow ranges, some are widespread, and a few have extremely small ranges. This distribution can be a result of speciation and extinction. Speciation adds new species, which inhabits a part of original range. It causes a reduction of original range. Old species, which are getting closer to their extinction, are also declining their range together with abundance. One of the interesting theories is the stochastic theory, it is based on stochastic differential equation. This equation describes a changes of range size towards its equilibrium, which is the value when the range size is in steady state. The next factor is abundance. It is known that species with more individuals occupy larger ranges. Abundance distribution is also log-normal. In this thesis, I would try to summarize theories which explains why the most of species have small range sizes and how range vary among similar species.
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