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Acoustic and visual signalization in birds: Identification of key components and their role in sexual selection
Mikula, Peter ; Albrecht, Tomáš (advisor) ; Svobodová, Jana (referee)
This bachelor thesis is focused on describing visual and acoustic signals in birds and their potential role in the process of sexual selection. Evidence that acoustic and visual signals are sexualy selected is summarized. The key characters that can be utilized in comparative studies are determined. In the first chapter of the thesis are briefly outlined mechanisms of sexual selection and evolution of costly secondary male ornamentation. In the second chapter basic avian ornaments (colouration, acoustic signals) are described. The emphasis is on visual and acoustic structures which are costly to produce and serve as honest indicators of individual condition. The third chapter is devoted to the possible trade-offs between visual and acoustic signalization in birds. The last section summarizes hypotheses about potential relationships between visual and acoustic signalization (and trade-offs between these two types of ornamental traits) in relation to changing environmental conditions.
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Environment and avian song: case of South African birds
Mikula, Peter ; Albrecht, Tomáš (advisor) ; Linhart, Pavel (referee)
Relationship between animal signalization and environmental conditions, where these species are living, is one of crucial topics of ecology. Using two complementary statistical approaches (fourth-corner and RLQ analyzes) I investigated geographical variation in parameters of bird vocalization in South Africa (RSA) and Lesotho. Altogether, I used nine quantitative and five qualitative acoustic traits for 472 bird species and nine environmental variables which could significantly influence parameters of their vocalization. My results supported findings of previous studies about the important effect of body size on species-specific vocal characteristics. In passerines, analyzes corrected for body size showed that the number of elements and element types were increasing with variability of natural conditions and were highest in very arid and climatically unpredictable areas. Element and element type rate were positively associated with altitude. Minimal song frequency in passerines and frequency range of vocalization in other birds were negatively correlated with average temperature of warmest and coldest month of the year, respectively. Similarly, environmental variables significantly influenced distribution of several qualitative song traits in passerines. Passerines, where female song and...
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Acoustic and visual signalization in birds: Identification of key components and their role in sexual selection
Mikula, Peter ; Albrecht, Tomáš (advisor) ; Svobodová, Jana (referee)
This bachelor thesis is focused on describing visual and acoustic signals in birds and their potential role in the process of sexual selection. Evidence that acoustic and visual signals are sexualy selected is summarized. The key characters that can be utilized in comparative studies are determined. In the first chapter of the thesis are briefly outlined mechanisms of sexual selection and evolution of costly secondary male ornamentation. In the second chapter basic avian ornaments (colouration, acoustic signals) are described. The emphasis is on visual and acoustic structures which are costly to produce and serve as honest indicators of individual condition. The third chapter is devoted to the possible trade-offs between visual and acoustic signalization in birds. The last section summarizes hypotheses about potential relationships between visual and acoustic signalization (and trade-offs between these two types of ornamental traits) in relation to changing environmental conditions.
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