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Land snail shell degradation in forest environment
Říhová, Dagmar ; Juřičková, Lucie (advisor) ; Horsák, Michal (referee)
Experimental shell degradation of nine common Central European pulmonate snail species in forest ecosystems in the Czech Republic was investigated. Model shells were deposited for 6, 12, 24 and 36 months in leaf litter of six different places; than removed, dried and photographed. Set of alternations was analysed by CANOCO 4.5 statistical system. Small species degrade different from large ones. Large species corrode outwards, after periostracum disruption the ostracum dissolves and holes appear. Small species corrode out from within, calcium carbonate dissolves and small windows arise. The shell degradation proceeds with different rate on various localities. Some localities have characteristic types of alteration, e.g. peat bog pine forest exhibits ostracum dissolution and periostracum deformation. The ultimate influence of the degradation is caused by pH value and humidity. Shell shape and size have effect on its degradation. Moreover, other important decomposition agents are living animals. Powered by TCPDF (www.tcpdf.org)
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Taxonomic revision of the genera Anisus in the Czech Republic (Mollusca: Planorbidae)
Zavoral, Tomáš ; Juřičková, Lucie (advisor) ; Beran, Luboš (referee)
The aim of this work is to critically review the anatomical and morphological characters being currently used in the determination of Central European species of the genus Anisus and to confront them with molecular characters. For the molecular analysis mitochondrial genes for 16S rRNA and cytochrome c oxidase - subunit I (COI) were used. DNA analysis showed that known species occuring in the Czech Republic form well distinguishable genetic lines. Subsequent revisions of the anatomical characters of these lines have proven that these characters are due to their variability not suitable for determination, especially for the differentiating of the species A. spirorbis and A. leucostoma. The conchological characters have proven more suitable, especially the ratio of the size of the last and penultimate whorl. With the help of this character, we can safely determine a population within which there are transitional forms in other morphological and anatomical characters.
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The influence of morphological and microstructural characteristics to land snail degradation in forest environment
Říhová, Dagmar ; Juřičková, Lucie (advisor) ; Bogusch, Petr (referee) ; Čejka, Tomáš (referee)
The decomposition of land snail shell is a complex process involving a number of factors and influences, including the characteristics of conchs themselves. In particular, it is the shell size with which the progress and the rate of degradation are tightly bound. Post-mortem changes begin with the loss of the original colour and, in the case of transparent species, by the opacification of the shell wall. Subsequently, the periostracum disruption and dissolution of calcium layers occur. However, this sequence may be reversed for some small species (e.g. Columella aspera, Nesovitrea hammonis). Animals mechanically destroy empty shells, humic acids from the substrate cause their artificial dyeing. Fungal mycelium or colonies of Streptomyces grow on the surface of the conchs. The plant roots are also involved in shell decomposition. While degradation of large shells starts with periostracum disruption and subsequent ostracal dissolution, periostracum of small shells persists even after dissolution of ostracal layers. The phenomenon is caused by high resistance of the periostraca of small species. In the case of large shells, periostracum has primarily a "building" function during shell formation, and sometimes it is flaking off already during the snail's life. For small species, it is an important part...
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Importance of flood drifts of the Ohře River for the study of alluvial mollusc communities
Ratajová, Michaela ; Juřičková, Lucie (advisor) ; Čejka, Tomáš (referee)
When water levels are increased, for instance in case of spring thaw and summer floods, various materials including terrestrial gastropods are pulled down from shores by water. This accumulated material is called flood drift and when interpreted accurately, its composition can provide useful information not only from faunistic point of view. In the past, flood drifts were used to supplement faunistic research of various areas, since it helps to reveal species which are difficult to detect using regular methods. This is also the case of the river Ohře. For the dynamics of molluscan association, water is a significant corridor connecting very similar places. I have attempted to verify, whether it is transported via a river bed, i.e. via stream corridor by means of flood drifts. The results of this theses confirm that gastropods are able to survive in the watercourse and cling several hundred metres down the stream. Thus we talk about short distance spreading. This transport is used by various terrestrial gastropods; however, bigger gastropods are much more likely to survive.
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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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Diversity of molluscan assemblages of temperate forests: model case of Křivoklátsko
Sobotová, Eliška ; Juřičková, Lucie (advisor) ; Dvořáková, Jana (referee)
1 Abstract: My bachelor thesis summarizes the impact of environmental factors and microhabitats on temperate forest snail assemblages: mainly on their diversity and abundance. Most authors consider humidity, calcium content and forest condition the main factors, which influence forest gastropod assemblages. However, othes have a different view on the importance of another factors such as composition of the forest vegetation, pH, the role of different sources of calcium carbonate. Some studies contradict themselves. My aim was also to point out these differences. Many of environmental factors are measurable with difficulties. Using of Ellenberg's indicator values seems to be an interesting alternative possibility to classical measurement. The importance of Křivoklátsko PLA is highlight as the landscape of continual forest development, which is unique within Central Europe.
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Palaeoecological aspects of Rhynchostreon Bayle oyster evolution
Rantuch, Jakub ; Košťák, Martin (advisor) ; Juřičková, Lucie (referee)
This paper presents a multilevel analysis of palaeoecological aspects of the process of the Rhynchostreon genera evolution. According to the latest results of research, the process of genus appears to be more dynamic than previously assumed.The processes of internal dynamics of the environment in conjuncture with other studied aspects of the late cretaceous environment (e.g. paleotemperature, salinity, etc.) were a significant factor that initiated the activity of selective pressure and represents an important factor in group evolution. In this work we provide the overall hypothesis about co-evolution of two intrageneric (sisters) lineages in Rhynchostreon genera. The definiton of evolutionary trends of intrageneric lineages within the presented hypothesis (including a new description of oyster species) is supported by various analytical methods, which anchors them in the current zoological nomenclature system. An electron microscopy, isotopes and biometrical analysis of a shell in cooperation with some of the sedimentologic methods suggest a relation of lithology (as a result of environmental aspect) and evolution process. The transregional concept of proposed ecological-evolutionary models, based on materials studies from various paleogeographic regions of cretaceous world, increases the...
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