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Vocalization of two nightingale species in their hybrid zone
Vokurková, Jana ; Petrusek, Adam (advisor) ; Osiejuk, Tomasz S. (referee)
6 ABSTRACT Bird song is a sexually selected trait that is crucial for mate choice and for maintenance of pre-mating reproductive barriers. Secondary contact of closely related and partially reproductively isolated song bird species may result in changes in their songs; these can either diverge and strengthen the reproductive barrier between the two species, or converge and contribute to mixing of their gene pools. The Thrush Nightingale (Luscinia luscinia) and its congener Common Nightingale (L. megarhynchos) may serve as model species suitable for studying these phenomena. In their secondary contact zone, an interspecific hybridization has been documented, as well as convergence of songs of Thrush Nightingales caused by copying of heterospecific songs. Such copying may be a result of erroneous learning of species- specific songs or by genetic introgression. We tested these hypotheses by simultaneous analyses of DNA and song recordings of both species from allopatry (Czech Republic and northeastern Poland) and sympatry (central Poland). Comparisons between our recordings and a catalogue of songs recorded in a Common Nightingale population from allopatry (Germany) confirmed that most of Thrush Nightingale males from the sympatric region were 'mixed singers' that use Common Nightingale phrases in their...
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Phylogeographic patterns and microevolutionary mechanisms in oceanic dolphins
Křišťanová, Žaneta ; Hulva, Pavel (advisor) ; Vokurková, Jana (referee)
This bachelor thesis discusses the current findings regarding the phylogeography of the Delphinidae family. It is mainly focused on phylogenetic structure and speciation of Delphinidae, as well as on the ways of differentiation of trophic niches and the evolution of ecotypes. In the past, the Pleistocene climate oscillation had a major influence on the development of individual species and populations. Currently, it is anthropogenic activities that cause fundamental changes in habitats and thereby change the living conditions for cetaceans. In several species of Delphinidae, the emergence of ecotypes has been recorded, where different populations of the same species use different ecological niches. This thesis is mainly dedicated to the ecotypes of the bottlenose dolphin (Tursiops truncatus). Variability in coloration, body length and spine morphology was noted for individual ecotypes. The spine is an important adaptation to the environment in Delphinidae. In this research, phylogenetic relationships between family of Delphinidae, life strategies and food niche of selected species of the genera Tursiops, Stenella and Delphinus are also described.
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Interspecific hybridization in birds: lessons for conservation
Štěpánková, Klára ; Reif, Jiří (advisor) ; Vokurková, Jana (referee)
Interspecific hybridization is quite common in recent years. Favorable factors are rarity of a species, limited time for partner selection, misdirected preference in mating partner selection of females, preference for males with more pronounced sexually selected traits, greater body size and habitat destruction. Factors which lead to the artificially interspecific hybridization due to habitat destruction include deforestation, fragmentation of the territory, urbanization, abandoning agricultural areas, as well as translocation of species into the regions where they did not originally occur. These species can later interbreed with the native species and if the latter are rare and the former aggressive, it can result in increased threat potentially leading to extinction of indigenous populations. Exceptionally, interbreeding can lead to the emergence of a new species; however, this type of origination of a new species is not common in animals. Hybridization is a natural phenomenon important for the evolution. Nevertheless, anthropogenically induced or assisted hybridization represents a serious problem for the species conservation. Finding a solution to overcome the negative impacts of such interspecific hybridization is difficult and there is no exact and universally applied methodology to date. Key...
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Mechanisms enabling individual recognition of passerine birds
Caha, Ondřej ; Petrusková, Tereza (advisor) ; Vokurková, Jana (referee)
Vocalization allows birds to communicate over long distances or in environments, where can be difficult to detect visual signals. Vocalization can be divided into songs and calls. Song may inform a listener of signal about species, sex, male quality, aggressive motivation and also about singer's identity. Recognition of different individuals is very valuable ability that is commonly used during territorial interactions among males. Correct identification of males, that pose different threat, enable to respond adequately to the situation and save energy or to avoid injury in potential conflict. The ability of individual distinguishing based on song was demonstrated by using playback experiments for many passerines, but it was rarely revealed the way of such identification. This review deals with the issue of neighbour-stranger experiments that confirm the ability of passerines to discriminate between neighbours and strangers. Further, it focus on structures or characteristics of birdsong enabling individual recognition of passerines and their possibly use for individual acoustic monitoring.
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Application of bioacoustic approaches in investigation of bird species interactions and community species richness
Vokurková, Jana ; Sedláček, Ondřej (advisor) ; Remeš, Vladimír (referee) ; Szymański, Paweł (referee)
Birdsong is one of the most fascinating communication tools in the animal kingdom, whether it is used for attracting a mate or in territory defense. In my dissertation, I present evidence that we can successfully study the role of birdsong in territorial behaviour, its seasonal variability, and ultimately its role in evolutionary processes thanks to modern bioacoustic and ecoacoustic approaches. By combining the bioacoustic approach with molecular analyses, I demonstrate that in the model system of two closely related passerine species, the heterospecific song convergence in their secondary contact zone is based on cultural transmission, and not on interspecific hybridisation and/or gene introgression. My dissertation further extends into the tropical zone, which is generally characterized by less pronounced environmental seasonality compared to the temperate zone. The study of potential seasonality in singing activity and the proportion of vocalizing species in this zone therefore requires year-round monitoring, which is possible thanks to the quite recent development of automated recording units (ARU). First, we confirmed that using ARU provides very similar estimates of community composition, species richness, and abundance to traditional field methods (point counts) in the specific conditions...
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Low-amplitude songs in songbirds
Belfín, Ondřej ; Petrusková, Tereza (advisor) ; Vokurková, Jana (referee)
Research of bird vocalisation has been remarkably growing in the past seventy years. However, most of the published papers focused on common high-amplitude vocalisation. Despite having researchers who considered the existence of another rare low-amplitude signal more than a century ago, low-amplitude songs were overlooked until the beginning of the 20th century. Additionally, authors still using terms for the description of this scarcely recorded vocalisations inconsistently, which makes the comparison of published papers difficult. In total, I found published notes describing the existence or function of low-amplitude songs in at least 45 species, with ten species having at least two different types. This review is providing evidence that low-pitch songs might be quite widespread but overlooked signals playing a role in male- male as well as male-female interactions. Moreover, it is possible to distinguish between several types of low-amplitude songs based on their structural resemblance to the primary song. Getting all together, I am providing new terminology that might be helpful for further conclusions and could be used in future research of this hidden phenomenon.
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Individual variation in vocalization of Carnivores
Švůgrová, Barbora ; Linhart, Pavel (advisor) ; Vokurková, Jana (referee)
For carnivorans, as well as for other groups of animals, it is very important to be able to recognize other individuals. In this thesis, I focused on individual vocal variation in carnivoran's calls. I reviewed studies which desribed individual variability of calls in carnivorans. I focused on studies which used diskriminant analysis to quantify individual variation in calls. I updated the review of Insley et al. (2003) who suggested that the ability of individual recognition is more advanced in the Otariidae compared to Phocidae. My quantitative comparison on individual variability of Otariidae and Phocidae voices shows that the reason could be that Otariidae have more individually distinct voices. Furthermore, I compared the inidivuality in calls of other carnivorans. The comparison results do not support the hypothesis that animals living in groups have individually more variable voices than the animals living solitairy or in pairs. However, individuality seems to be influenced by ontogeny as it is easier to individually recognize calls of adults than calls of juveniles. In general, there have been many studies published about vocal individuality in carnivorans, but most of the research was done on just two very social families: Otariidae and Phocidae. It is necessary to study other carnivora...
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Mechanisms enabling individual recognition of passerine birds
Caha, Ondřej ; Petrusková, Tereza (advisor) ; Vokurková, Jana (referee)
Vocalization allows birds to communicate over long distances or in environments, where can be difficult to detect visual signals. Vocalization can be divided into songs and calls. Song may inform a listener of signal about species, sex, male quality, aggressive motivation and also about singer's identity. Recognition of different individuals is very valuable ability that is commonly used during territorial interactions among males. Correct identification of males, that pose different threat, enable to respond adequately to the situation and save energy or to avoid injury in potential conflict. The ability of individual distinguishing based on song was demonstrated by using playback experiments for many passerines, but it was rarely revealed the way of such identification. This review deals with the issue of neighbour-stranger experiments that confirm the ability of passerines to discriminate between neighbours and strangers. Further, it focus on structures or characteristics of birdsong enabling individual recognition of passerines and their possibly use for individual acoustic monitoring.
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Interspecific song copying in birds: causes and evolutionary consequences
Kohoutová, Hana ; Reifová, Radka (advisor) ; Vokurková, Jana (referee)
Bird song is very important for communication in birds, especially in passerine birds. It helps to define male territory and singing is also used to attract a femalein mating season. Singing is also important for maintenance of prezygotic reproductive barriers in many bird species. In various species of birds, especially in closely related, there may occur heterospecific copying of singing. This phenomenon is also known as the mixed singing. Mixed singing is emerging in different avian species by various mechanisms. Mostly this is an error during the learning phase of singing, but in some cases copping of singing may be adaptive. The aim of this thesis is to sumarize the existing knowledge and findings about mixed singing, also to describe known examples of mixed singers in closely related species, present hypotheses that may explain the origin of mixed singing, and discuss ecological and evolutionary significance of this phenomenon. Key words: birds, songs, mixed singing, vocal mimicry, sister species
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