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Among-population variability in yellowhammer songs: causes and consequences
Bílková, Jana ; Petrusková, Tereza (advisor) ; Reif, Jiří (referee)
The inter-population geographic song variability can be found in many bird species. One of the most interesting types are dialects, characterized by sharp boundaries between populations of individuals sharing the same particular song type. Despite many years of investigation there is no satisfactory answer to the question how these borders persist over the years at nearly same sites. Distinctions between dialects allow recognition of males from different populations and could influence the territorial behaviour. Various habitats, however, degrade the sound differently; it is therefore possible that specific habitats are preferred by individuals with specific dialects. Both social interactions and acoustic properties of the locality could also be only secondary factors and the dialect distribution could be the result of the habitat distribution either in present or in recent past. In this diploma thesis, several hypotheses were tested on the example of Yellowhammer (Emberiza citrinella) - a songbird abundant in open land with simple song and easily recognizable dialects. The thorough data concerning the habitats and dialect distribution were obtained at the dialect borders at two localities in Czech Republic. The reactions of territorial males to both foreign and their own dialects were also...
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Inter-population variability of the bird song
Bílková, Jana ; Petrusková, Tereza (advisor) ; Musilová, Zuzana (referee)
Inter-population variability of the song is widespread phenomenon among birds. Populations of same species from different geographical areas might differ in vocalization. In case of dialects there are even no transitions between particular song forms, but clearly demarcated boundaries. Although the majority of studied cases concerns songbirds, it is possible to find examples in other orders as well. Studies showed that individuals inhabiting forests sing shorter and simpler songs with a lower frequency than their relatives from open landscapes. Changes in temporal and frequency characteristics can also be found in populations living in noisy cities. Different songs, however, are also produced by individuals from populations whose habitats do not show any significant differences. If these groups also differ genetically, then the different variants of song could be caused by heredity, especially in species with innate song. However, this variability may be the consequence instead of the cause of assortative mating, which might be the result of interpopulation variability in some cases. In species where the song is at least partially learned it is more likely that social interactions will play the key role - particularly if females prefer males singing local dialect or if sharing the song with neighbors...
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