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Evolution of brain size in birds
Straková, Barbora ; Němec, Pavel (advisor) ; Remeš, Vladimír (referee)
Vertebrates show dramatic interspecific variation in the size of their brains. The complexity of brains is considered to be the key factor of evolutionary success in Vertebrates, and therefore an evolutionary trend towards increasing brain size and coplexity is assumed. Large and complex brains evolved independently in birds and mammals. Birds have brains that are comparable in their relative size to the brains of mammals. However, in stark contrast to mammals, there is no general trend towards increase of brain size in birds. Relatively large brains have evolved independently in many avian lineages. Highly encephalised orders are parrots (Psittaciformes), woodpeckers and relatives (Piciformes), hornbills, hoopoe and wood hoopoes (Bucerotiformes), owls (Strigiformes), storks (Ciconiiformes) and several families of songbirds (Passeriformes), mainly bowerbirds (Ptilorhynchidae) and corvids (Corvidae). Otherhighlyencephalizedgroupsarenon-parasiticcuckoos(genusCentropus,Phaenicophaeus and Coua) and family Diomeidea and genus Pelecanus belonging to the clade water birds. Less encephalized groups include the basal lineages such as paleognaths and fowl (Galloanserae), and also pigeons (Columbiformes) and swifts, treeswifts and hummingbirds (Apodiformes). We suggest that this mosaic evolution is result of...
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Social Brain Hypothesis: A Survey of Evidence
Kverková, Kristina ; Němec, Pavel (advisor) ; Pavelková, Věra (referee)
The social brain hypothesis was first proposed to explain the remarkable cognitive abilities of primates and has since been extended to other taxa. Generally, it posits that sociality is a major selection pressure driving the evolution of large brains and intelligence. However, there is no single version of the hypothesis and different underlying mechanisms have been proposed. Tests of the hypothesis rely on appropriate indices of social complexity and brain size, as a proxy for cognitive abilities, and difficulties are associated with choosing both these variables and obtaining precise data. Situation is further complicated by that fact that a multitude of factors potentially contributing to or constraining encephalization is highly intercorrelated. This bachelor's thesis reviews approaches to research in this field and presents a survey of relevant evidence accumulated so far. The social brain hypothesis has been tested in various ways in primates, carnivores, ungulates, cetaceans, insectivores, bats, birds, fish (cichlids), and insects. The jury is still out, since contrasting results exist for most of these groups, warranting more research to help elucidate the influence of sociality on brain evolution.
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