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Population biology and evolutionary genetics of southern right whale (Eubalaena australis)
Nevečeřalová, Petra ; Hulva, Pavel (advisor) ; Galov, Ana (referee) ; Robovský, Jan (referee)
Southern right whale (Eubalaena australis) is a species from the Balaenidae family with a range in the southern hemisphere, which evolved in connection with Neogene climate oscillations. Its population biology involves migration between coastal waters of South America, southern Africa, Australia and New Zealand to its high-latitude foraging and feeding grounds in the Southern Ocean. Intensive historical hunting from the 18th to 19th century has impacted the population dynamics of baleen whales substantially. After the whaling moratorium, the species has been recovering from the heavy exploitation, however, recently it is facing anthropogenic changes, such as climate change. The South African population, considered to be the largest one globally and intensively studied for the last several decades, is showing an increase in the calving interval, a decline in female condition and a dramatic shift in migration routes since 2010, possibly as a consequence of significant changes in marine food webs. Methods of molecular ecology were applied to monitor the population genetics and its dynamics not only in the context of the global population but also to compare different time periods - 1990s and 2010s. The majority of the samples were collected noninvasively in cooperation with commercial whale-watching...
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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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