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Drivers of avian diversity on an altitudinal gradient of Mount Cameroon
Djomo Nana, Eric ; Hořák, David (advisor) ; Šálek, Miroslav (referee) ; Waltert, Matthias (referee)
Altitudinal gradients constitute a powerful test system for understanding distribution of species around the globe. Tropical mountains are quite rich in species even after controlling for environmental productivity, and are ideally suited for studying patterns of species distributions because they have had sufficient time for species to produce a response to environmental changes that affect their life histories. In this thesis, I investigate basic ecological mechanisms potentially behind avian distribution patterns along an altitudinal gradient in West-Central Africa. I used data collected with four methodological approaches (point counts, mist netting, random walks and artificial nest experiments) along an altitudinal gradient on Mt. Cameroon from October 2011 to September 2013. This work is focused on two interrelated themes: selection pressures on life histories (Chapters 1, 2, 3 & 4), and avian assemblage structures (Chapters 5 & 6). In the General Introduction, I present an overview of the study area with conservation implications of the study and my study objectives. In Chapters 1, 2 & 3, I investigate how selection pressures, i.e., nest predation and parasitism by haematozoa, affect bird assemblages. I used artificial nest experiments to assess nest predation rates in Chapters 1 & 2, and my...
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Relationship between functional and species diversity of birds in South Africa
Džamba, Roman ; Hořák, David (advisor) ; Šímová, Irena (referee)
Species distribution and composition of bird communities of South Africa is not accidental, but is influenced by environmental conditions, habitat structure, and natural history of the area. Functional traits of the species (morphology, dietary strategies or reproductive parameters) give information on how the individuals interact with the environment they live in. The description of the functional characteristics, expose specific adaptations and the role of the species in the studied ecosystem. On the basis of functional characteristics we are able to estimate functional diversity of studied community. The spatial variability of species and functional diversity allocates longitudinal gradient. Regarding the morphological and reproductive parameters that are continuous in nature and more species- specific, we observe a faster increase in functional diversity. Considering the feeding preferences that are categorical and show a limited number of levels, a modest increase in functional diversity apparent is. Dietary functional diversity is more evenly distributed. Relationship between the functional and species diversity can provide us with information about how species are added to the community or answer the question to what extent the higher number of species requires more ecological space. The...
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Functional diversity in ecological communities
Džamba, Roman ; Hořák, David (advisor) ; Doležal, Jiří (referee)
Functional diversity is an important component of biodiversity. Value and range of functional traits and the number and composition of functional types are crucial for the short and long term functioning of ecosystems. Functional traits of species affect their performance in ecosystems and we can classify them as continuous or discontinuous. It has been suggested many ways to choose the appropriate traits and functional differences between species in estimating functional diversity. It is necessary to consider the nature and importance of ecosystem processes and environmental factors and consider properties of employed methodological approaches. There are many ways to estimate functional diversity. Functional diversity can be expressed by the number of functional groups, functional index or functional dendrograms. In natural communities, we see a positive relationship between species and functional diversity. Species diversity doesn't seem to be an adequate surrogate for functional diversity because the loss of an equal number of species may have different effects on the ecosystem, depending on the identity of the species. Functional redundancy refers to the functional similarity in the ecological niches occupation and is a source of stability in the ecosystem functioning.
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