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Miocene fish fauna from the Cheb and Sokolov Basins: taxonomic overview and palaeoecology
Hakalová, Pavla ; Přikryl, Tomáš (advisor) ; Mazuch, Martin (referee)
The aim of this thesis is to present an overview of Miocene fish fauna of the lacustrine sediments in the Cheb and Sokolov Basins, geological settings of this area, and fish associations in individual biozones. Sediments of Cheb and Sokolov Basins were deposited during time interval from Eocene until Miocene in the subtropical zone of the North hemisphere. Volcanic and post-volcanic activities of the Ohárecký rift influenced development of these basins. It's possible define two time sections within development of these basins: early and later; both of them provide rich record of fossil fishes. For the early period of the development is typical smaller range of the lake and its shallow depth. The relicts of this stage are limited to Cheb Basin mainly. Fish fossil record is limited, with three species only: Esox sp., Palaeotinca egeriana and Leuciscus (Palaeoleuciscus) socoloviensis. Low fish diversity could have been affected by poor living conditions or lower taxonomic diversity in general during this time. The later developmental period was much longer. The lake was much bigger - it spread to Sokolov Basin also. The fish fauna diversity is much higher, including taxons Paleotinca egariana, Leuciscus (Palaeoleuciscus) socoloviensis, Aphanius chebianus, Paralebias egeranus and Gobius sp. It is...
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Sperm maturation process in fishes (review)
KŘIŠŤAN, Jakub
The main aim of this thesis was to review the current knowledge in the field of fish sperm maturation (a process where immature spermatozoa acquire the potential to respond to motility-activating factors) and the urogenital system structure in relation to this maturation.
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Analysis of karyotype and sex chromosome differentiation in African annual killifish of the genus Nothobranchius (Teleostei: Nothobranchiidae)
Lukšíková, Karolína ; Sember, Alexandr (advisor) ; Zrzavá, Magda (referee)
Teleost fishes (Teleostei) encompass more than half of the extant vertebrate biodiversity. Their genomes display considerable plasticity and flexibility, going hand in hand with polyploidization events and repetitive DNA dynamics. Teleosts also display a striking diversity in mechanisms of sex determination and differentiation. The aim of the present thesis was to study the mechanisms underlying the karyotype and sex chromosome differentiation through cytogenetic mapping of repetitive DNA (by fluorescence in situ hybridization, FISH) in selected representatives of the African annual killifishes of the genus Nothobranchius (Teleostei: Nothobranchiidae). Nothobranchius spp. evolved a unique adaptation to freshwater temporary water pools whose existence is limited to periods of rainy season in African savannahs. Recent diversification, allopatric speciation in non-overlapping generations and small-sized populations together with known cytogenetics collectively suggest fast dynamics of chromosomal changes in Nothobranchius killifishes. The study took advantage of the availability of i) more populations of several closely related species for analysis and ii) data on specific repetitive DNA composition in selected Nothobranchius genomes as revealed by RepeatExplorer analysis. My work showed considerable...
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Fossil marlins (family Istiophoridae) from the Piña locality (Panama; Chagres Formation; Miocene) - morphology and comparison with related forms
De Gracia Castro, Carlos Fernando ; Přikryl, Tomáš (advisor) ; Carnevale, Giorgio (referee)
The study of fossil istiophorids is limited by its fragmentary fossil record; the absence of osteological specimens for comparisons; the cryptic bibliography of several early works and the absence of more accurate comparative methods. Appling a data imputation model we took advantages of extant data for rostral and articular variables for istiophorid billfishes. We used this result to apply PCA analysis and we compared fossil and modern istiophorids together. With this analysis we present here two new istiophorid species: Makaira? sp. nov. 1 and Makaira sp. nov. 2. Makaira? sp. nov. 1 is the most complete fossil istiophorid ever discovered and represent that share characters in various genera. We hypothesize that characters in bones involved in alimentation process have phylogenetic importance as: rostrum shape, denticles, lower jaw, vomer, basioccipital and skull shape as well as orbital size. Our taxonomic reviews of fossil istiophorid reorganize its taxonomy and solve many conflicts about the classification of fossil species. The istiophorids are abundant macrovertebrate in the Chagres sediments and its presence suggests a water column with a minimum of 200m depths in an environment of short platform with oceanic influence. Given the high productivity inferred in this environment we suggest that...
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Cytogenetics of selected groups of ray-finned fishes (Actinopterygii): Evolutionary-ecological questions associated with the dynamics of repetitive sequences and the occurrence of polyploidy
Sember, Alexandr ; Ráb, Petr (advisor) ; Marec, František (referee) ; Král, Jiří (referee)
Ray-finned fishes (Actinopterygii) exhibit the greatest biodiversity among vertebrates. The vast majority of extant actinopterygian fish species belong to clade Teleostei - a lineage whose significant evolutionary success might have resulted from a teleost specific whole- genome duplication (TSGD) that occurred at the onset of this group, subsequent to its divergence from the rest of actinopterygian lineages. Despite the growing body of sequenced fish genomes and analyses of their transcriptomes, the largest contribution to understanding fish genomes comes from analyses of DNA content and from cytogenetics. Genomes of ray-finned fishes and especially those of Teleostei exhibit vast diversity and rapid dynamics of repetitive DNA sequences whose variability is reflected in a wide range of fish genome sizes and in the dynamics behind karyotype differentiation. Therefore, ray-finned fishes offer a unique opportunity to study genome variability as a driving force underlying morphological and ecological diversification, evolution and adaptation. Particularly, the mapping of repetitive DNA sequences by means of fluorescence in situ hybridization (FISH) has proven to be a very useful and informative approach during the last two decades and contributed greatly to our understanding of the fish genome...
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Miocene fish fauna from the Cheb and Sokolov Basins: taxonomic overview and palaeoecology
Hakalová, Pavla ; Přikryl, Tomáš (advisor) ; Mazuch, Martin (referee)
The aim of this thesis is to present an overview of Miocene fish fauna of the lacustrine sediments in the Cheb and Sokolov Basins, geological settings of this area, and fish associations in individual biozones. Sediments of Cheb and Sokolov Basins were deposited during time interval from Eocene until Miocene in the subtropical zone of the North hemisphere. Volcanic and post-volcanic activities of the Ohárecký rift influenced development of these basins. It's possible define two time sections within development of these basins: early and later; both of them provide rich record of fossil fishes. For the early period of the development is typical smaller range of the lake and its shallow depth. The relicts of this stage are limited to Cheb Basin mainly. Fish fossil record is limited, with three species only: Esox sp., Palaeotinca egeriana and Leuciscus (Palaeoleuciscus) socoloviensis. Low fish diversity could have been affected by poor living conditions or lower taxonomic diversity in general during this time. The later developmental period was much longer. The lake was much bigger - it spread to Sokolov Basin also. The fish fauna diversity is much higher, including taxons Paleotinca egariana, Leuciscus (Palaeoleuciscus) socoloviensis, Aphanius chebianus, Paralebias egeranus and Gobius sp. It is...
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