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Mechanisms of relationship between melanin-based colouration and behavioural syndromes in birds
Nacházelová, Martina ; Javůrková, Veronika (advisor) ; Tomášek, Oldřich (referee)
Melanins are the most common pigments incorporated into birds' feathers. Since melanin-based coloration is variable in the extent and intensity, its function is considered to be particularly cryptic and mechanical, hardening the feather structure. However, recently it has been found that melanin- based coloration also has a signaling function, due to the observed correlation between this type of coloration and many physiological and behavioral traits. These relationships follow from the pleiotropic effects of genes regulating the melanocortin system and the physiological effects of testosterone and corticosterone, which are involved in melanogenesis. This work describes genetic and physiological mechanisms of the relationship between melanin-based coloration and behavioral traits in birds and, based on available studies, supports the signaling function of this type of coloration. Melanin-based coloration has been shown to be positively correlated with aggressiveness and dominance, sexual activity, coping with stress, a fast strategy of exploratory behavior, parental care, and anti-predator behavior in many bird species. However, despite intense research interest in this topic in last decade, it is worth noting that more experiments focused on species with a distinct sexual dichromatism or...
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Epigamic behaviour in male Northern Lapwings: variability of visual attributes of song-flight and their relationships with other reproductive traits
Nacházelová, Martina ; Šálek, Miroslav (advisor) ; Exnerová, Alice (referee)
The Northern Lapwing (Vanellus vanellus) is a species with conspicuous courtship rituals, the most noticeable part being the males' aerobatic song-flight. The aim of this study was to determine which song-flight characteristics are important in female mate choice and whether the perceived difficulty of the song-flight is correlated with other indicators of male quality. In 2014 and 2015 male lapwings were observed in the meadows and arable land in South Bohemia, Czech Republic, in the vicinity of České Budějovice, a traditional breeding area. In 24 males we video-recorded their song-flights and observed mating behaviour and/or incubation of nests, had they any. We measured various aspects of the most dramatic displays of agility and stamina in the song-flight (Ascent, Vertical Dive, and Alternating Flight) in order to find which of them acted as influencing factors in female mate choice. We found that the more complicated the pirouette in the Vertical Dive and the faster the pace of the Alternating Flight, the earlier the male nested. The most convincing result showed that the longer the male spent more or less vertically inclined along his longitudinal axis in the Alternating Flight on one side before revolving to the other, the higher the probability for him to establish a polygynous bond - attract more...
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Mechanisms of relationship between melanin-based colouration and behavioural syndromes in birds
Nacházelová, Martina ; Javůrková, Veronika (advisor) ; Tomášek, Oldřich (referee)
Melanins are the most common pigments incorporated into birds' feathers. Since melanin-based coloration is variable in the extent and intensity, its function is considered to be particularly cryptic and mechanical, hardening the feather structure. However, recently it has been found that melanin- based coloration also has a signaling function, due to the observed correlation between this type of coloration and many physiological and behavioral traits. These relationships follow from the pleiotropic effects of genes regulating the melanocortin system and the physiological effects of testosterone and corticosterone, which are involved in melanogenesis. This work describes genetic and physiological mechanisms of the relationship between melanin-based coloration and behavioral traits in birds and, based on available studies, supports the signaling function of this type of coloration. Melanin-based coloration has been shown to be positively correlated with aggressiveness and dominance, sexual activity, coping with stress, a fast strategy of exploratory behavior, parental care, and anti-predator behavior in many bird species. However, despite intense research interest in this topic in last decade, it is worth noting that more experiments focused on species with a distinct sexual dichromatism or...
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