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Maternal Care in Spiders
Foxová, Doris ; Opatová, Věra (advisor) ; Raška, Jan (referee)
Maternal care is any behaviour of the mother which directly benefits its offspring usually at the cost of future reproduction of the female. Many types of maternal care are known among spiders, but a comprehensive review of all different types of maternal care across spider diversity is still largely missing. With the summarisation of research concerning maternal care and thanks to the implementation of genomic data and subsequent advances in spider systematics and evolutionary research, different types of maternal care are interpreted in an evolutionary context and mapped on the up to date phylogenetic tree. Guarding behaviour is common across spider families. On the contrary, various forms of feeding are rare. Some phenomena (matriphagy and regurgitation) evolved repeatedly in distantly related spider families.
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Genome size variability and its relationship towards selected biological characteristics of arachnids
Šilhavá, Veronika ; Opatová, Věra (advisor) ; Urfus, Tomáš (referee)
Genome size, also called C-value, describes the amount of DNA contained in haploid set of chromosomes in organism. Knowledge of this value can be useful for example as indicator of technical difficulty and financial cost of projects using genome seqencing, or it can be used for taxonomic purposes as well. Genome size encompasses immense variability across the animal kingdom. We also encounter variability among arachnids, even between species within the same genus. However, the relationship between genome size and biological characteristics of arachnids has not been examined so far. In this thesis, I assembled genome size data for all arachnid orders alongside with a variety of their biological characteristics. These traits were subsequently mapped onto the phylogenetics trees. In certain arachnid orders, the genome size could be related to the body size, life span and potentially also to ecology (e.g. web type, retreat). Unfortunatelly, genome size data are available only for a small portion of Arachnida diversity, which complicates the interpretation.
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Spider diversity research in relation to habitat conservation management.
Krajíčková, Kateřina ; Opatová, Věra (advisor) ; Dolejš, Petr (referee)
Spiders are a cosmopolitan and highly diversified group of invertebrates that play a very important role in the ecosystem. Thanks to their ubiquity in anthropogenic and economic ecosystems, we can consider them a suitable group that can be used for biological protection needs. Spider venoms and their silks also have potential uses in biotechnology in the future. Today, however, spiders face many threatening factors, including climate change, habitat loss, pesticides, acid rain, and other introduced invertebrate species. Spider conservation is currently addressed in several ways, using regional instruments such as the Bern Convention, the Habitat Directive and the IUCN Red List of Endangered Species. However, in the EU in particular, there is a lack of efforts to protect them not only in terms of evaluation but also in terms of regional and national legislation. However, the fact that they may be located in protected areas, such as national parks or protected landscape areas, also helps to protect them, which greatly helps to maintain their diversity. The biggest obstacle to spider protection is the lack of public support, which can be linked to ignorance and concern. These concerns could theoretically be addressed by pointing out that very few spider species pose a threat to humans and by educating...
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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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Phylogeographic patterns of the spider species complex Dysdera erythrina
Opatová, Věra
The ability to delimit species boundaries is essential in taxonomic studies. However, different methods of delimitation may give ambiguous or contradictory results, thus integration of multiple approaches is often necessary for correct species recognition. This is especially true for taxa originated in recent radiations that may not have had sufficient time to accumulate morphological apomorphies, in which case a strictly morphology based approach would underestimate the real species diversity. In this regard, molecular methods became a useful tool for species delineation. The woodlouse hunter spider Dysdera erythrina is considered a sibling species complex with wide geographic distribution (Iberian Peninsula to Georgia). Three species have been separated from D. erythrina in the past, however their current taxonomic position remains unclear. In this study an integrative approach combining molecular (one nuclear, four mitochondrial genes) and morphological data is used for species delimitation. Molecular data are further used in order to reconstruct the phylogenetic relationships among the lineages and estimation of the time frame of their diversification. In the phylogenetic analyses Dysdera fervida and D. lantosquensis formed independent monophyletic clades supported also by morphology, but D....
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Phylogeny and evolution of the family Megastigmidae (Hymenoptera: Chalcidoidea)
Böhmová, Julie ; Janšta, Petr (advisor) ; Opatová, Věra (referee)
The family Megastigmidae (Hymenoptera: Chalcidoidea), one of the hymenopteran parasitoid families, is unique in containing many species with phytophagous larval feeding strategy. A number of species of different genera are seed-feeders and the genus Bortesia is even capable of inducing galls. The family Megastigmidae is found mainly in the Australian region but a few genera/species groups are widespread throughout different areas, mainly in the Oriental and the Holarctic region. The main goal of this study was to map phylogenetic relationships among genera and clarify the following: the overall number of transitions between a parasitoid and a phytophagous way of life, the ancestral feeding strategy of the family, the evolution of feeding strategies in the genus Megastigmus, and the geographical area of origin of the family. The questions were tested based on a phylogeny reconstructed by a state-of-the-art method - sequencing of "Ultra-Conserved Elements (UCEs)" - using 100 specimens of Megastigmidae from 11 out of 12 currently valid genera selected taking into consideration their feeding strategy and biogeographical origin. The final dataset contains 1210 loci (570,000 base pairs in length) and most nodes are supported by bootstrap value 100. The results show that the family can be divided into 3...
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Adaptations of terrestrial arthropods and especially arachnids to arid environmental conditions
Byronová, Markéta ; Starostová, Zuzana (advisor) ; Opatová, Věra (referee)
The biggest problem that terrestrial animals have to deal with is the risk of dehydration. Water is lost by evaporation during respiration and through the body surface, during excretion and various secretions. Terrestrial animals developed various physiological, morphological and behavioral adaptations against water loss. This work summarizes the knowledge about adaptations against water loss in arthropods in arid environmental conditions. It focuses on arachnids and especially on scorpions, which are widespread in arid areas and show high resistance to extreme desert conditions. The work examines the influence of environmental conditions on physiological processes in the body, morphological adaptations and behavioral changes. It defines specific adaptations of scorpions and describes in more detail the role of the hepatopancreas in maintaining the balance of fluids in the body and the subsequent changes in the osmolarity of hemolymph. Key words: evaporation, aridity, water balance, arthropods, arachnids, scorpion
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Phylogeographic patterns of the spider species complex Dysdera erythrina
Opatová, Věra
The ability to delimit species boundaries is essential in taxonomic studies. However, different methods of delimitation may give ambiguous or contradictory results, thus integration of multiple approaches is often necessary for correct species recognition. This is especially true for taxa originated in recent radiations that may not have had sufficient time to accumulate morphological apomorphies, in which case a strictly morphology based approach would underestimate the real species diversity. In this regard, molecular methods became a useful tool for species delineation. The woodlouse hunter spider Dysdera erythrina is considered a sibling species complex with wide geographic distribution (Iberian Peninsula to Georgia). Three species have been separated from D. erythrina in the past, however their current taxonomic position remains unclear. In this study an integrative approach combining molecular (one nuclear, four mitochondrial genes) and morphological data is used for species delimitation. Molecular data are further used in order to reconstruct the phylogenetic relationships among the lineages and estimation of the time frame of their diversification. In the phylogenetic analyses Dysdera fervida and D. lantosquensis formed independent monophyletic clades supported also by morphology, but D....
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