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National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
An intensity of plumage bacterial load and resistence against bacteria-caused feather degradation in tropical birds of Afromontane areas of Cameroon
 Kyptová, Markéta ; Javůrková, Veronika (advisor) ; Adamík, Peter (referee)
Microorganisms are considered to be a significant selective factor affecting bird's life strategies. The body cover, including feather, is occupied by a wide range of bacteria that are in their host in different interactions. Group of microorganisms degradate keratins of feather is still most studied and most species of birds have them in feather. This feather degrading bacteria can disrupt the wear and its function and thus cause great losses to its fitness. Therefore, it seems likely that these feathers degrading bacteria and microorganisms generally play a significant role in creating defence mechanisms against their negative effects. One of the most important defence mechanisms to protect feathers against the action of microorganisms is the deposition of melanin pigments. This diploma thesis deals with the analysis of the total bacterial load in feathers and its resistance against bacterial degradation in 47 species of birds trapped in afromontan areas of western Cameroon. The specific aim of the thesis was to determine differences in the total number of bacteria in plumage in species with different life strategies, especially feeding and reproductive strategies. At the same time, the phtilochronological analysis of the quality of the plumage was performed and in vitro experiments were tested...
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Melanin-based ornaments of birds and their relationship to individual condition
 Straka, Antonín ; Svobodová, Jana (advisor) ; Karlíková, Zuzana (referee)
This thesis summarizes findings from literature about the melanin pigment and its properties, melanogenesis, factors affecting the synthesis and tissue deposition of melanin, methods for analysis of ornamental traits of birds, and the relationship of melanin-based ornaments and individual condition. Current studies show that the expression of melanin plumage can be condition-dependent; size or chroma of ornaments frequently signals individual condition. The relationship between condition indicators and the melanin pigment is found more often in achromatic species than in species with melanin- and carotenoid-based plumage. There's a lack of research dealing with pheomelanin ornaments. Statistical analysis of data obtained from adult male great tits (Parus major) captured during the nesting seasons 2014 and 2015 on sites Čimický háj and Ďáblický háj in Prague was carried out to test the relationship between the size of the melanin-based breast stripe and standardized weight, absolute leukocyte count and tarsus length. Results didn't confirm a link between the area of the breast ornament and analyzed indicators of condition. Future research will take into account other condition parameters which could contribute to explain the role of the breast stripe in sexual selection in the great tit.
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