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Shape, surface and microstructural characteristics of landsnail shells and theirs function.
Holubová, Anna ; Juřičková, Lucie (advisor) ; Bogusch, Petr (referee)
Snails are popular group of invertebrates which intrigues people with their shell. Land snail shells take a variety of shapes and colors, their surface is covered by various surface structures. Shape of the shell is often afected by the environment in which snails live. Elongated shells are found on snails crawling along vertical surfaces, however snails with flattened shells crawl primarily on a horizontal surface. Keeled snails often hide in cracks in the rocks and under stones. Just as the shape is affected by the environment, so can the environment affect the surface structure and microstructure of the shell. We can find a snail with a shell that is covered with hairs in a humid environment and snails with thick periostracal layer in acidic one. The findings summarized in this thesis can be helpful to paleontological reconstructions of the environment, and in morphological identification of recent species by their shells.
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Comparison of Natural and Human-influenced Malacocenoses of the Krasíkov Village
Šiřinová, Veronika ; Říhová, Dagmar (advisor) ; Podroužková, Štěpánka (referee)
The aim of this diploma thesis is to compare natural and human-influenced malacocenoses in the vicinity of the villages Krasíkov and Domaslav in the district of Tachov, Czech Republic. Inventory research was conducted between 2012 and 2013. A total of 36 gastropod species were found, and a total of 1088 snail shells were collected. On some of the surveyed sites (the farm Krasíkov, Domaslav, the pond near Ovčí vrch) the influence of anthropic stress is evident. Four species found during this study are also listed in the Red List of Threatened Species of the Czech Republic (Aegopinella nitidula, Balea perversa, Ena montana, Vertigo pusilla). Based on the results of the research, two variants of the didactic use of a such malacological research were created in the teaching of natural science and biology. Keywords: Mollusca, Gastropoda, malacocenosis, species diversity, ecology of mollusk assemblages, Krasíkov.
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The influence of geology to the diversity of molluscan assemblages
Krajinčáková, Lucie Linda ; Juřičková, Lucie (advisor) ; Myšák, Jan (referee)
Molluscan populations are influenced by various factors of environment where they occur. In my work I am taking particular atention of soil properties, which are directly influenced by the geological substrate, and of course other factors which are with soil properties either directly or indirectly related. The important benchmarks are especially moisture, pH, calcium content and vegetation cover. This bachelor thesis also deals with utilization of calcium salts. Geological substrate is closely linked with the diversity and abundance of molluscan populations. Various pedochemical factors affect molluscan communities whether it is the amount of calcium in the soil or a pH value. In the past different authors found different dependencies between environmental factors, species composition and diversity of molluscan communities. Most of the studies were focused on very specific habitats and locations. In this thesis I tried to organize our knowledge about the specific effects of various environmental factors, especialy compositíon of geological substrate on malakofauna. Key words: Mollusca, Gastropoda, Geological substrate, diversity
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Food preferences of land snails in a river flood-plain invoved with invasive plants
Ševčíková, Štěpánka ; Juřičková, Lucie (advisor) ; Čejka, Tomáš (referee)
Food preferences to five most widespread invasive plant species from river floodplains: Impatiens glandulifera, Helianthus tuberosus, Fallopia japonica, F. sachalinensis a F.x bohemica and one native species - U. dioica were studied on two common land snail species. Using three different methods I tried to recognize, whether or not these plants serve as a food source to Succinea putris and Urticicola umbrosus. From histological sectionsit was impossible to identify the plants. The majority of plants don`t provide structures usable for identification of plant in the snail maces. I was able to identify only H. tuberosus and U. dioica undoubtedly, thanks to trichomes. According to the results of laboratory tests, the most important factors for snails food preferences are plant species and the condition of plant material. U. umbrosus consumed much less fresh material than S. putris. Consumption of frozen leaves became larger for both species. The most preffered plant species were U. dioica and H. tuberosus. Only frozen I. glandulifera was consumed. Fallopia spp. were rejected both, fresh or frozen.
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On the Nothernmost and Southernmost Limits of European Land Snail Spatial Ranges
Křepelová, Lucie ; Juřičková, Lucie (advisor) ; Horsák, Michal (referee)
The aim of this work was to evaluate the limits of ranges of European land snail species along the north-south gradient. To work out the document it was necessary to prepare the set of digitalized maps, that enabled to create the database of ranges of the individual land snails species. Based on obtained data I tried to identify places where the northern and southern borders of species ranges are the most frequent. The landsnails' ranges are affected not only by particular life requirements of the individual species (potential limits), but also by other conditions, especially climatic, geographical and historical (truncated limits). In this work I focused on their differentiation. Above mentioned process also enabled me to track the north- south changes in species richness of the landsnails taking into consideration the truncated and potential limits. The most important natural barriers constraining that numerous of species cannot naturally widespread from the south to the north are the Scandinavian Mountains, the Alpes and the Carpathians and suprisingly also southern borders of german and polish lowlands. On the other hand, spreading of the species form the north to the south is limited only by the Alpes. I also tried to distinguish the group of species whose ranges are not influenced by these...
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Diversity of methods used for characterization of molluscan hemocytes
Jindrová, Zuzana ; Skála, Vladimír (referee) ; Horák, Petr (advisor)
Hemocytes are the main immune cells of invertebrates; therefore they can be found in molluscs, too. They differ both in morphology and function. The two generally accep- ted morphological types, granulocytes and hyalinocytes, vary in the level of phagocy- tosis and encapsulation, production of reactive oxygen species and nitrogen oxide, and presence of some enzymes. There is an array of methods by means of which hemocy- tes can be characterized. Microscopy serves particularly for study of morphology. An- tigens localized on the surface can be determined by monoclonal antibodies or lectin probes. Hemocytes can be divided on the basis of cell size and granularity using gra- dient centrifugation or flow cytometry. Production of nitrogen oxide and reactive oxy- gen species is monitored by adding appropriate substrate which changes its proper- ties after reaction with the radical. It may become fluorescent, change absorbance of the solution or form a visible precipitate. Another possibility is the use of chemilu- miniscence. The objective of hemocyte research is to explain mollusc-pathogen inter- action. 1
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Evolutionary strategy in biomineralization of mollusc shells: Micromechanical properties of shells and their relationship with the environment
Hrabánková, Iva ; Frýda, Jiří (advisor) ; Marika , Marika (referee)
This thesis deals with the micromechanical properties (microhardness and elastic modulus) of selected molluscan shell microstructures and their relationship to crystallographic textures and environment. Results of the study suggest that extremely high hydrostatic pressure has a relatively weak influence on the mechanical properties of calcitic as well as aragonitic shell layers. No statistically significant difference was found in microhardness and elastic modulus of nacre between bivalvian species living in marine and freshwater environments. On the other hand, the study reveals a statistically significant positive correlation between the micromechanical properties and thickness of aragonitic platelets forming the nacre. Unexpected result is a negative correlation of the degree of ordering of aragonitic platelets with both elastic modulus as well as microhardness. Thus the degree of ordering explains about 80% of the variability of these micromechanical properties. Statistically significant but weaker correlation was also found between micromechanical properties and textural type of bivalvian nacre. The nacre with uniaxial texture is harder and more elastic than the nacre with quasimonocrystallic texture. The data suggests that higher hardness and elasticity corresponds to a primitive state of nacre and that during the subsequent evolution values of these micromechanical properties were decreasing. This trend contradicts with generally accepted hypothesis of increassing predation pressure in the marine ecosystem during the Paleozoic and Mesozoic.
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Risks arising from breeding and introduction of aquarium snails
Jarošová, Martina ; Vrabec, Vladimír (advisor) ; Jan, Jan (referee)
Information was gathered regarding all aquarium and already introduced alien snail species (Gastropods), which are being imported to Europe. For the integrity of the research non-native and aquarium clams (Bivalve) were also included. Profiles of species were created based on collected information and the data were subsequently used for creating questionnaires. Questionnaires of each species were processed by FI - ISK, version 1.19 screening tool. Score of invasiveness risk potential was evaluated for each species individually. Surveyed taxa were divided into three groups according to their scores: low risk, medium risk and high risk. Celetaia persculpta was evaluated as aquarium snail (Gastropods) with the lowest risk for native fauna of Czech Republic. According to the results, Pomacea maculata and Pomacea canaliculata are the aquarium snails (Gastropods) with the highest invasiveness risk potential. The riskiest introduced species is Potamopyrgus antipodarum. Scabies crispata and Hyriopsis bialata are clams (Bivalve) with the least risk for the native fauna of Czech Republic. Corbicula fluminea and Dreissena polymorpha were analyzed as clams (Bivalve) with the highest invasiveness risk potential. By comparing aquarium species with species that were already introduced into Czech nature, I conclude that the aquarium snails (clams) do not represent similar risk like the alien species that were introduced without the share of aquarists.
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The complex characterisation of nematode Phasmarhabditis hermaphrodita
NERMUŤ, Jiří
Ph.D. thesis "The complex chacterisation of the nematode Phasmarhabditis hermpahrodita" is focused on the study of ecology of slug parasitic nematode P. hermaphrodita, its general characterisation in the context of all nowadays knowledge. The thesis consists the general introduction, that introduces the whole nowadays research of P. hermaphrodita, and four original works, that follow the introductory chapter. The first work deals with the orientation of P. hermaphrodita in 2D and 3D space and reaction on the presence of different hosts or nutritive substrates. The other study deals with the reaction of P. hermaphrodita on various animal and plant nutritive substrates and in the first place the influence of these substrates on the development of nematodes and quality and quantity of progeny. The third scope of this thesis is the influence of intraspecific competition on development, quality and quantity of nematodes and the last part of this text comprises a short study of the persistence of P. hermaphrodita in different substrates, from mineral to organic.
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