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Aphidophagy among polyphagous predators
Valdecká, Miriam ; Řezáč, Milan (advisor) ; Dolejš, Petr (referee)
Aphids are among the most widespread insect pests in agroecosystems. So far, significant attention has been paid to their natural enemies, especially to specialized predators and parasitoids. There is less information about the influence of polyphagous predators, especially spiders and ground beetles. Therefore, the aim of this thesis is to summarize the knowledge about this topic. And focus on the advantages and disadvantages of aphidophagy in polyphagous predators. Key words: Aphid, aphidophagy, polyphagous, spider, carabid, predator
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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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Arachnophobia and the cause of fear of spiders
Říha, Roman ; Dolejš, Petr (advisor) ; Vlček, Kamil (referee)
Fear of spiders is largely widespread, and in some cases may even grow into a phobia. Negative attitude towards spiders can be found already in the mythology of some peoples. This attitude is often in the Western culture. It is interesting that this fear persists even though there are very few spiders which are able to endanger human life. There are more possible causes of arachnophobia, including classical conditioning, information transmission and impact of disgust emotions. Right the disgust seems to be the probable explanation of spider phobia. Relevance fear is documented by a list of dangerous spiders to humans. Some spiders are in fact able to endanger human health by toxins contained in their venom. Basic questions to deal with are validity of human fear of spiders and possible causes of this negative relationship.
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The consequences of low dispersal capability on diversity and distribution of spiders.
Schweiner, Ladislav ; Opatová, Věra (advisor) ; Dolejš, Petr (referee)
Spiders represent a highly diversified group. In terms of their dispersal capability, they can be classified in two categories: vagile and sedentary. Vagile spiders, most of the Araneomorphae infraorder lineages, are better adapted for dispersal thanks to their ballooning capability and generally more active lifestyle compared to the sedentary spiders, mostly belonging to the infraorders Mygalomorphae and Liphistiomorphae. The manner of dispersal and its efficacy represents a key factor for the colonization of new habitats and maintaining gene flow among the populations of the same species. Limited dispersal capability is responsible for the tendencies to local endemism in sedentary groups. This thesis aims to summarize our knowledge about the dispersal capabilities of sedentary spiders and the effect of vicariance and allopatric speciation on their distribution. The thesis provides a brief overview of dispersal barriers and evaluates their effect on the gene flow among the populations. The data proceeding from studies focused on selected sedentary spider lineages suggest that dispersal barriers have a strong negative effect on gene flow among their populations. Limited gene flow thus leads to genetic diversification and subsequent speciation. Key word: Dispersal, dispersal barriers, endemicity,...
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Phylogeny and diversity of harvestmen suborder Laniatores
Marešová, Alexandra ; Hiřman, Matyáš (advisor) ; Dolejš, Petr (referee)
This bachelor thesis summarizes the general knowledge about phylogenesis, diversity and distribution of harvestmen from the suborder Laniatores. Until recently, phylogenetic relationships of this suborder were very few studied, but thanks to a recent studies they are still improving. The suborder Laniatores now includes 41 families, which are divided into ten superfamilies. An overview of distribution of individual families of the suborder Laniatores is also given in this work and so are factors influencing it. From abiotic factors there is humidity, temperature, climate, and altitude. Among biotic factors, the distribution may be influenced by the type of vegetation or by the human, where it is mainly the introduction of invasive species. The greatest emphasis is placed on morphological differences between individual families. The biggest differences can be observed on their bodies, especially in the form of different numbers and types of sclerotized protrusions. Keywords: harvestmen, Laniatores, phylogenesis, biogeography, biodiversity, morphology
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Study on dynamics of spinning apparatus of some wolf spiders (Araneae: Lycosidae) during their life cycle
Dolejš, Petr
Current knowledge of the spinning apparatus comes namely from studies on orb web spiders and their relatives, whereas that of wolf spiders were more or less neglected. Therefore, developmental changes of the spinning apparatus of four wolf spiders were studied throughout their life cycles. Each of these lycosids possesses stenochronous life cycle with similar number of instars (7-10) but of different length (1-3 years). There is only one period of reproduction in spring/summer in all four species. Sperms are being formed just after the final moult; diplotene in some species is peculiar. The courtship behaviour reflects the microhabitat occupied by the concrete spider species; the copulations are species specific. Ontogeny of the spinning apparatus of developing spiderlings was observed: The spinning apparatus initiate its function in the first instar. Secondary ampullate, all piriform and all but four aciniform glands are tartipore-accommodated; they do not moult in situ. The tartipores, vestigial structures corresponding to spigots of the previous instar, appear on the spinning field starting with the second instar. Tartipore-accommodated glands play roles also during proecdysis and their evolution corresponds with the way how do the spiders secure themselves when moulting. Hence, the not yet...
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