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Social learning in birds: mechanisms and importance in different contexts
Ernestová, Kamila ; Exnerová, Alice (advisor) ; Stehlík, Patrik (referee)
Social learning, i.e. learning from other individuals of the same or different species can be found in a large number of taxa and the birds are no exception. Authors of a large number of studies focusing on this topic demonstrated the influence of social learning on various aspects of birds' life. Undoubtedly, the most important aspects of birds' life are recognition of predators, mate choice, and acquisition of food and food choice. Tool-related behaviour such as tool making and tool using in order to obtain food is also related to the foraging context. However, social learning often plays a different role in different contexts in different species. The differences in acquisition and use of social learning in some contexts exist even within a single species. These differences are mainly caused by individual personality, sex, age and partly also by social status and different ontogenetic factors influencing individual development. Social learning is a very broad topic with large number of variables and, despite the intensive research, it is still not fully understood. Keywords: social learning, birds, social learning mechanisms, imitation
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Cellular composition of brains for hornbills, woodpeckers and coraciiform birds
Stehlík, Patrik ; Němec, Pavel (advisor) ; Kratochvíl, Lukáš (referee)
Recent comparative studies have shown that bird brains, although small, have a high processing capacity. The brains of parrots and songbirds have higher neuronal densities than brains of mammals; especially large parrots and corvids compete with or even outnumber primates by the number of telencephalic neurons. However, the processing capacity of the avian brain appears to differ significantly between various phylogenetic lineages. Basal groups such as galliform birds have much lower absolute numbers of neurons and lower neuronal densities than songbirds and parrots. In this Master thesis, I used the isotropic fractionator to determine numbers of neurons and non-neural cells in specific brain regions in 19 species of hornbills (Bucerotiformes), woodpeckers (Piciformes) and coraciiform birds (Coraciiformes). The brains of hornbills and woodpeckers (but not coraciiform birds) have numbers of neurons comparable to that of songbirds and parrots and significantly more neurons than equivalently sized brains of pigeons (Columbiformes) and galliform birds (Galliformes). In the crown groups, we can observe similar trends such as a higher degree of encephalization, a proportionally larger telencephalon and increasing percentage of telencephalic neurons. On the contrary, in pigeons and galliform birds, we can...
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Evolution of the telencephalon in amniotes
Stehlík, Patrik ; Němec, Pavel (advisor) ; Druga, Rastislav (referee)
Structural organization of the telencephalon differs starkly among mammals, birds and non-avian reptiles. No clear homologue of the mammalian six-layered cerebral cortex has been identified in other vertebrate groups. In the last century, this topic has sparked heated disscussions in the field of comparative neurobiology. Available data point to clear homologies between telencephalic subpallial regions among all amniotes. Many hypotheses have been proposed about homologies within the pallium that offer contrasting reconstructions of the evolution of the aminote telencephalon. While earlier hypotheses suggest homologies at the level of neural circuits and embryological territories, the most recent hypothesis suggests homology at the level of individual cell types possessed by a last common ancestor of reptiles, birds and mammals. The resulting diametrically different structures have been organized by different developmental mechanisms. However, recent transcriptomic data are in direct conflict with these claims, and support the hypothesis which assumes that higher cognitive functions in both major lineages of amniotes evolved independently by expansion of different embryonic fields. The aim of this bachelor's thesis is to provide comprehensive information about the proposed homologies and hypotheses...
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