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Vocal communication of cetaceans (Cetacea) with emphasis on development and learning
Zvěřinová, Adéla ; Šimková, Olga (advisor) ; Nevečeřalová, Petra (referee)
Vocal communication is the main mean of communication for cetaceans. Just like the species themselves, their repertoires are diverse, consisting of tonal, pulsed, and combined calls, with frequency and amplitude modulation. The two groups of cetaceans, Mysticeti (baleen whales) and Odontoceti (toothed whales), produce sounds of different parameters, mainly frequency, bandwidth, and duration. Both production and contextual learning can be found in cetaceans. It is used to acquire two types of sounds: signature calls and songs. Signature calls are present only in species living in stable groups or fission-fusion society. They are used as an identification tool to maintain cohesion and contact with conspecifics. Songs are present in most baleen whales, but only humpback and bowhead whales' change within and between seasons. They use vocal learning to conform to one type used by all individuals. It is also employed during vocal development in ontogenesis, together with maturation. Calves and juveniles' calls are chaotic, lacking in structure. With age, they gain stereotypy and resemble adults' repertoire. Key words: cetaceans, vocal communication, signature calls, vocal learning, cultural transmission
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Body size as an implicit factor: case studies of life-history strategies and behaviour
Šimková, Olga ; Frynta, Daniel (advisor) ; Sedláček, František (referee) ; Rehák, Ivan (referee)
Body size has a potential to influence almost any trait in animal biology. The thesis contains four case studies (I - IV) covering four various situations and four various taxa, mainly squamate reptiles (Lepidosauria). Body size is a connecting factor for all these studies, in which I and my co-authors tried to elucidate various implications of body size. I. The sex ratio in Cuban boa (Chilabothrus angulifer) litters is often male or female biased. The neonates are so large, that are able to accept the same type of prey as are adults (in contrast to the other Chilabothrus species). We found that both the sexes are of the same size and shape at birth. Large size of the neonates a long lifespan lead to considerable generation overlaps. This could clarify our findings that small females produce sons whereas the larger ones deliver daughters. Males are smaller than females, probably also less philopatric and refuse food during breeding season. We can conclude that females manipulate the sex ratio of neonates according to its own body size, in order to decrease the probability of competition with their own offspring. II. Mangrove-dwelling monitor lizard (Varanus indicus) shows one of the greatest degrees of sexual size dimorphism among monitor lizards. We recorded the growth of the individuals from...
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Selfrecognition, selfawareness and other cognitive functions in cetaceans
Jachnická, Kristýna ; Šimková, Olga (advisor) ; Adamová, Dana (referee)
Self recognition is highly discused topic in cognitive sciences. Experiments on a level of behavioral (mirror test, reference tests of body parts using) show that animals usually are able to realize parts of their own body. There are several experimental evidence among cetaceans of this kind that proved that they are conscious of their own body parts (self awareness). There are also many other complex cognitive skills that can be predisposition to self recognition or that can prove that cetaceans are conscious of they own mind (self consciousness). Powered by TCPDF (www.tcpdf.org)
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