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Latitudinal trends in avian life-histories
Krejčířová, Zuzana ; Albrecht, Tomáš (advisor) ; Reif, Jiří (referee)
Most studies on bird focus on northern temperate zone species. However, the vast majority of birds occupies tropical environments. In birds, differences between tropical and temperate zone species in various life-history traits have long been assumed. These differences may reflect variation in solving the survival-reproduction trade-off, with temperate species preferring actual reproduction over the survival and tropical species preferring the oposite. In this bachelor thesis I summarize the result of literature search focusing on latitudinal trends in selected life-history traits in birds. In the first part of thesis I provide an overview of differences between the temperate and tropical zone in environmental conditions often assumed to closely affect the evolution of avian life histories. In the second part of the thesis, I focus on particular life-history traits where the differences between tropical and temperate species were detected. Latitudinal trends in chosen life history associated traits (clutch size, longevity and life span, basal metabolic rate) indeed seem to correspond with the general prediction of comparatively slow pace of life in tropical species.
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The utilization of "doubly labelled water" method in studies of avian ecology
Míčková, Kristýna ; Albrecht, Tomáš (advisor) ; Kubička, Lukáš (referee)
Doubly labelled water method is used to estimate CO2 production and energy expenditure. The method is based on the application of water containing rare hydrogen and oxygen isotopes, and estimation of the difference in elimination of these isotopes from the body (used as an indirect estimate of CO2 production), which is measured mostly from two blood samples taken over a defined time interval (usually 24 hours). Here I summarize the assumptions and methodological approaches associated with the use of the doubly labelled water method in bird studies. Studies on birds typically evaluate energy expenditure associated with prasitic infections and immune response, ageing, investments into the reproduction, flight and migration, ornamentation. In comparison with other methods doubly labelled water is appropriate for measurement of energy expenditure associated with various aspects of biology in targeted individuals. Key words: Doubly labelled water, energy expenditure, metabolism, birds, reproductive investments, flight costs
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