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Reactions of spider and insect predators to aposematic prey
Koláčná, Klára ; Exnerová, Alice (advisor) ; Sentenská, Lenka (referee)
Aposematic prey advertises its unprofitability to predators by means of warning signals, which can be visual, chemical, acoustic or combined with each other as multimodal signals. Most experimental studies dealing with responses of predators to aposematic prey focus on vertebrates, especially birds. This thesis focuses on the most frequently tested groups of terrestrial arthropod predators - spiders, dragonflies, and mantises - supplemented by less tested insect predators. Most of the tested arthropod predators are able to learn to avoid noxious aposematic prey based on either visual, olfactory or acoustic signals depending on their perception. Some can remember this aversion for several days. Only in case of jumping spiders, ability to generalise previous experience with a particular prey to similar prey has been confirmed. Prey chemical defenses most often consist of cardenolides or aldehydes, which proved to be aversive for tested arthropod predators.
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Vliv světelných podmínek listnatých lesů I. a II. vegetačního stupně na epigeickou faunu pavouků
Surovcová, Kamila
The objective of the present study was to investigate the impact of canopy openness and associated light conditions on epigeal spider assemblages in abandoned coppice forests in order to develop conservation recommendations for forest management in lowland woodlands. In particular, I studied the effect of canopy openness gradient on species richness, abundance, functional diversity, community composition, conservation value, and degree of rareness of spiders. There was established transects reflecting the canopy openness gradient in each of the eight forest stand. A total number of 90 spider species, including high proportions of xeric specialist and red-listed threatened species. The peaks of conservation indicators, as well as spider community abundance, were shifted toward more open canopies . On the other hand, functional diversity peaked at more closed canopies followed by a rapid decrease with increasing canopy openness. Species richness was highest in the middle of the canopy openness gradient, suggesting an ecotone effect. Ordinations revealed the rapid species turnover along canopy openness gradient with presence of most conservationally important species in sparse and open conditions. The results show that the various components of biodiversity peaked at different levels of canopy openness. Therefore, the restoration and suitable management of such conditions (e.g. conservation thinning, coppice management) will retain important diversification of habitats in lowland oak forests. According to these results, even small-scale activities supporting these conditions could be suitable conservation tools to slow down the general decline of woodland biodiversity.
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Agrární terasy jako refugium xerotermních organismů - příklad z okolí Veverských Knínic
Hamřík, Tomáš
The main aim of this bachelor thesis is to explore if agrarian terraces provide a suitable refuge for xerothermic species of spiders. Two slopes within the agrarian terraces area near Veverské Knínice, which are used for growing arable crops, were chosen for the research. Spiders were chosen as a bioindicative, model organism. The spiders were collected using pitfall traps, which were placed in three succession stages: sparse, dense grass turf and bush. Eighteen pitfall traps were placed in six lines. One line consisted of three traps and each of the lines was placed in a different succesion stage. The collection was carried out eight times on the following days: 19. 6. 2014, 24. 7. 2014, 29. 8. 2014, 6. 10. 2014, 20. 11. 2014, 3. 6. 2015 and 29. 6. 2015. Overall, 635 samples were collected and identified as 66 species of 44 genus and 16 families. Altogether, 40 xerothermic species were collected, with five of these species listed on the Red List of Czech spiders (VU = 4, EN = 1). These species were: Micaria formicaria, Nematogmus sanguinolentus, Neottiura suaveolens a Xysticus striatipes, which are typical for steppes or forest-steppes. The most significant finding was Sibianor tantulus, recorded within the Czech Republic only for the third time. The statistical Analyses of Variance found that the type of succesion stage does not affect the number of species observed. Species of spiders are evenly spread within terraces. This means that it is very important to preserve a mosaic of habitats within slopes of agrarian terraces. The results indisputably demonstrate the conservation value of agrarian terraces as a refuge for xerothermic organisms.
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Biogeography of arachnofauna of the Alps
Šilhavá, Alena ; Šťáhlavský, František (advisor) ; Řezáč, Milan (referee)
This bachelor thesis gives a summarizing overview of the biogeography of arachnofauna of the Alps. It covers five orders of arachnids residing in the Alps, namely scorpions (Scorpiones), pseudoscorpions (Pseudoscorpiones), palpigrades (Palpigradi), harvestmen (Opiliones) and spiders (Araneae). The work is focused on the distribution of endemic and subendemic species of these orders of arachnids and on factors that can influence their distribution and total diversity in the Alps. It turns out that temperature and humidity are important factors. Pseudoscorpions occur more frequently in warmer areas at lower altitudes, while especially scorpions of the genus Euscorpius (Alpiscorpius) and harvestmen are more tolerant to areas with a lower temperature, while harvestmen especially require sufficient humidity. For spiders in the mountains of the Alps total species richness and density decreases mainly from open land to the forest. Total diversity in the Alps has also been influenced by temperature oscillations during the Quaternary climatic changes and different positions and types of refugia. This is apparent at the species closely related to soil environment, such as palpigrades or cave pseudoscorpions of the family Syarinidae. Key words: biogeography, the Alps, endemic, Scorpiones, Pseudoscorpiones,...
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Ecology and courtship behaviour of the wolf spider genus Alopecosa (Araneae: Lycosidae)
Just, Pavel ; Dolejš, Petr (advisor) ; Žďárek, Jan (referee)
In my bachelor thesis, Czech members of the wolf spider genus Alopecosa are discussed. Literature review summarizes our knowledge in ecology of wolf spiders, their life histories, phenology and habitat preference. I concentrated on reproduction of wolf spiders of the genus Alopecosa, especially on their courtship behavior. Recently, spider courtship is studied with focus on multimodal signalling. The review also contains remarks about spiders life cycles, copulation and parental care. Research of courtship of the genus Alopecosa is sligthly neglected, especially when we consider achievements gained by study of the American wolf spiders of the genus Schizocosa. It is necessary to know the taxonomy of the genus Alopecosa, thus some taxonomical remarks about current systematics and phylogeny of family Lycosidae are outlined
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Viniční terasy jako refugia pro výskyt xerotermních druhů pavouků (Araneae) a jejich bioindikační využití v hodnocení kvality životního prostředí a úrovně biodiverzity
Košulič, Ondřej
The large-scale decline of traditionally managed early-successional habitats caused by the joint effects of agricultural intensification and abandonment of marginal lands has resulted in a critical reduction of xerophilous arthopods throughout Europe. The question is whether newly generated early-successional sites of human-made habitats (in this case vineyard terraces) may partially compensate this habitat loss. My research, therefore, focusses on spiders as model organisms to determine the potential importance of xeric slopes of vineyard terraces for biodiversity conservation in agricultural landscapes. I analyzed species density, abundances, rareness degree and conservation value among vineyard terraces with two habitat types of different succession stages (sparse and dense grass turf) placed in in landscapes with varying proportions of surrounding potential source areas (steppe -- foresteppes) and different surrounding habitats (habitat structure) around studied terraces. During 2011 were collected by different methods 6040 adult specimens of spiders belonging to 171 species, 69 genus and 24 families. From this representation were calculated high proportion of rare xeric specialist (40 %) and red-listed threatened species (15 %). From the statistical analyses, overall species density and abundance of spiders did not differ significantly between the terraces with sparse and dense vegetation cover, however species density was significantly influenced by presence of xeric grasslands around vineyards. The occurence of rare and endangered epigeic was significantly associated with the type of successional stage (for epigeic and epiphytic species), as well as rareness degree, conservation value and abundances significantly increased with presence of adjacent steppe grasslands. The results indicate that artificial habitats, such as vineyard terraces, are important refuges for wide spectra of xerothermophilous spiders. To prevent losses of rare and endangered xeric species, I suggest some small scale management methods that maintain important microhabitat mosaic structures under the different succession stages.
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Characters used for determining of spiders (Araneae)
KRIŠTOFOVÁ, Lucie
This bachelor thesis focuses on a current issue of classifying spiders into their families. The incorrect recognitions of a family are often caused by inappropriate choice of morphological features and their ambiguous characteristics for determination usage. In a literary review, various morphological characters of spiders used for their determination to families are summarized and described. Subsequently, two Czech keys were tested by respondents, which provided a view of the steps and features causing difficulties in classifying spider families. Thus, I outline both unquestioning acceptance of features from older sources and the fact that their usage is not always a reliable tool for determination. Often neglected is the attitude of inexperienced observers who look upon the spider body inexpertly, not being influenced by arachnological traditions, and therefore, with a certain dose of exaggeration, objectively. This is the reason why the research was done mainly with the help of amateur public. In the final parts of the bachelor thesis, I both discuss problems that emerged and were recorded during the observation and recommend suitable improvements concerning the classification keys.
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Epigeická fauna v požářišti revíru Bzenec (LS Strážnice)
Prágr, Jakub
The aim of this thesis was to discover the actual condition of the epigeic fauna of a vast fire area (165 ha) in the first growing season after the fire in a habitat in Bzenec (LS Strážnice). Pitfall traps were used to determine the condition of the epigeic fauna. These were placed on sites deforested after the fire, in vegetation left to its natural successional development in a differentiated age after the fire and concurrently in unaffected vegetation. 16,267 specimens of 226 species of mostly epigeic fauna were caught. The impact of habitat conditions changed by the fire and timber harvesting were closely analysed for Carabidae, Araneae, Opiliones and Myriapoda taxons. There was a difference in the species composition of the epigeic fauna between the sites which were disturbed and undisturbed by the fire. Important factors that caused changes in the development and composition of the fauna after the fire were light conditions, humidity and trophic resources of the site. It was proved that the Pterostichus quadrifoveolatus (Carabidae) and Xerolycosa nemoralis (Araneae) species prefered the sites disturbed by the fire. The Carabus violaceus (Carabidae) or Harpactea rubicunda (Araneae) species were mostly bound to the sites undisturbed by the fire.
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