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Fragmented populations of freshwater pearl mussel (Margaritifera margaritifera) in nonwadable rivers in Czech Republic
Zolich, Radek ; Simon, Ondřej (advisor) ; Korábek, Ondřej (referee)
Margaritifera margaritifera is a critically endangered species of freshwater bivalve. The protection status is regulated by both the legislation of the Czech Republic and local regulations. The aim of this thesis was to map the current occurrence of M. margaritifera in Czech streams and to verify assumptions about its occurrence in Otava near Horažďovice. Furthermore, the parameters of the shells of dead individuals, which are in the collections of the National Museum in Prague and the Czech University of Life Sciences, were also measured. A total of 642 shells collected from the Vltava, Teplá Vltava, Malše and Otava were available, while only the relevant part, specifically 509 shells, were used for separate evaluation. Differences in the morphological parameters of the shells depending on the locality and their possible correlation with the stream order of the Otava, Vltava, Teplá Vltava and Malša were investigated. Thanks to the findings from the mapping of living freshwater pearl mussels, a proposal was drawn up to modify the methodology of bivalve research in the Czech Republic, which is part of the Rescue program of freshwater pearl mussels, led by the AOPK of the Czech Republic. Key words: Freshwater pearl mussel, shell, morphology, stream order, AOPK methodology, diving operations
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Genetic delineation of species in cladocerans (Crustacea, Cladocera)
Korytová, Nikola ; Sacherová, Veronika (advisor) ; Korábek, Ondřej (referee)
Cladocera (Crustacea, Branchipoda) are a diverse group of planktonic crustaceans. There are many cryptic species which form species complexes. Families Daphniidae and Chydoridae who live in water bodies around the whole world, have not completely resolved taxonomy so far. Mophological and genetic analyses are used for identifying species. It is often preferable to study their genetic distances, because they frequently hybridize. The genetic markers (DNA sequences that are unique to each species) are used for the genetic analysis of taxa. Although mitochondrial genes provide better results on a species level, nuclear genes may also be used. Cytochom c oxidase subunit I (COI), 12S and 16S rDNA are the most used mitochondrial genes. However, the situation in families Daphniidae and Chydoridae is complicated and assigning precise genetic distance for delineation of the species is not easy, although these genes allow well-supported phylogenetic trees. The future studies should examine more closely the dating events and create molecular clocks, especially for the family Chydoridae, which is often neglected despite its species diversity. Key words: Daphniidae, Chydoridae, genetic markers, COI, 12S rDNA, 16S rDNA
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Diversity of the land snail genus Helix and its relatives (Gastropoda: Pulmonata: Helicidae) from Mediterranean origins to postglacial Central Europe
Korábek, Ondřej ; Juřičková, Lucie (advisor) ; Hausdorf, Bernardt (referee) ; Cameron, Robert A.D. (referee)
5 ABSTRACT The family Helicidae comprises the largest and most widely known land snails of the Western Palaearctic. Yet the knowledge of its diversity until recently relied largely on morphology-based taxonomic work from the early 20th century. Molecular phylogenetic data were needed to resolve several taxonomic issues and to understand the biogeographic history of the group. This thesis focuses on an Eastern Mediterranean group of helicid genera, and in particular on the type genus of the family, Helix Linnaeus, 1758. From exploring the diversity and relationships of Eastern Mediterranean and Anatolian lineages, this work follows them on their way from diversification centre up to the postglacial fauna of Central Europe. The results are based on analyses of sequences of mitochondrial genes, conchological examinations, and radiocarbon dating of Holocene subfossils. First, we compared the lineage diversity of Helix with the conclusions of a recently published morphology-based taxonomic revision. We assembled a representative dataset covering almost all species of the genus as now recognized, as well as most of potentially related genus-level taxa. We refined the genus limits, revealed several species whose delimitation may require further revision, and pointed out probable differences in how species are...
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Phylogeny of the genus Helix (Mollusca: Gastropoda: Helicidae)
Korábek, Ondřej ; Juřičková, Lucie (advisor) ; Horáček, Ivan (referee)
The land snail genus Helix comprises large gastropods distributed in from France to Iran and in North Africa. Some of them have close linkage to humans - are synanthropic or are collected and consumed. The genus is most diverse in eastern Mediterranean. Taxonomy of the genus is now being revised from morphological point of view, and a molecular study is needed as a counterpart to that study. Here I present first phylogenetic data for the genus Helix, including almost all currently recognised species. I have used samples from various sources including dried bodies and tissue remnants. I have sequenced two commonly used mitochondrial markers (16S, COI). Position of the genus within Helicidae cannot be inferred from the dataset. The genus should be delimited in a strict sense, excluding genera Maltzanella, Cantareus, Cryptomphalus and Lindholmia. Division into subgenera, as proposed by various authors until now, is not supported with the exception of a split between subgenera Pelasga and the nominotypical Helix. Relationships between species and their groups are poorly resolved. Regarding species limits, the data are largely in agreement with new opinions based on morphology. There might be surprisingly high variability in shell characters within a species, as few morphologically characteristic taxa seem to be...
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Summary of the taxonomy of the genus Helix.
Korábek, Ondřej ; Juřičková, Lucie (advisor) ; Král, David (referee)
Despite the genus Helix Linnaeus, 1758 (Gastropoda, Pulmonata) comprises large and common land snail species, it is rather neglected by taxonomists. A vast number of species and subspecies level taxa were described along 19th century, most of them currently not considered as valid. Nevertheless, there remain doubts about species delimitation. It is obvious, that there is great morphological variability in some species, but little is known about its taxonomic value. Today, about forty valid species are recognized. The diversity center of this genus is situated in northeastern Mediterranean. The distribution data of particular taxa are fragmentary and ecology of some species is largely unknown. No collections are still available from extensive areas, thus completion of field collecting can lead to changes in status of some taxa or perhaps even to description of new species. This work is based on the review of available literature and partly also on the study of collection materials. It provides a list of available names in the genus Helix in its present sense. The problems of traits used for species identification as well as weak points of current knowledge of diversity of the genus Helix are briefly discussed.
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