eDNA microarray technology has generated a tremendous amount of interest among biologists because of its promise to monitor the entire genome on a single chip, thus enabling researchers to have a better picture of the interaction among thousands of genes simultaneously. In the current study, this technology was used to print over 3,000 unknown genes from various silk glands of the black widow spider to profile their expression patterns and to identify novel candidates. Spiders are remarkable creatures because of their ability to make different silks, each with a specific function. Some of these silks have amazing mechanical properties, comparable to those of the finest synthetic materials. Several silk genes have been cloned from various spiders over the last few years, and the contribution of each of those genes in silk production has been identified. However, the majority of cellular and biochemical processes involved in silk manufacture remain a mystery. In our research, we attempt to identify genes that might be involved in silk assembly, on a global scale and investigate more about those genes and their interplay with other key biological molecules involved in silk manufacture. Our study showed that silking spiders for a certain period of time resulted in down-regulation of two important silk genes, ECP-1 and ECP-2. Both these genes are key molecules implicated for their role in maintaining the egg case architecture in the black widow spider.,-and we believe that these genes are also directly or indirectly involved in the manufacture of dragline silk. Microarray analyses also enable the discovery of several other interesting molecules, two of which could be accessory proteins involved in silk formation. Furthermore, in a separate study we also characterized a novel silk glue protein with unique ensemble repeats. In conclusion, we believe that the findings of this study will indeed be significant to silk researchers and material scientists alike and it will enhance our knowledge in understanding the mystery behind silk production.

Spider silk is one of the most remarkable materials produced in the natural world and its strength and extensibility are legendary. To date, the majority of studies have been performed on the following silks: dragline, capture spiral, and eggcase silk. The primary goal of this study was to characterize a lesser known silk type, called wrapping (swathing) silk, from Latrodectus hesperus. My research focused on elucidating the fibroins that make up the swathing silk. Perfonning MS/MS analyses on solubilized wrapping silk fibroins digested with trypsin, we demonstrate that a novel fibroin named AcSp !-like is present within wrapping silk. Consistent with this finding, SEM analyses reveal that wrapping silk is a composite material, containing at least three different diameter silk fibers. By using scanning electron micrographs, along with amino acid composition analyses and MS/MS analyses, we demonstrate wrapping material contains the fibroins AcSp1-like, MiSp1-like, MaSp1 and MaSp2. These are the first studies to reveal that minor, major and acinifonn silks are constituents of wrapping material.

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The purpose for using pesticides is to kill organisms that cause damage (so-called pests) on various crops and thus prevent possible crop losses. Their side effect is a negative impact on non-target organisms. The presented diploma thesis is focused on the effect of neonicotinoids on invertebrates particularly on spiders. Its main goal was to document their influence on behavioral parameters influencing dispersal abilities such as locomotion and tendency to spread by wind (so-called ballooning). The diploma thesis compares the influence of neonicotinoids on model species, Pardosa lugubris (Walckenaer, 1802) and Phylloneta impressa (L. Koch, 1881) with different modes of prey hunting and compares the influence on adult and nymphal stages. Pesticides Actara® 25 WG, Biscaya® 240 OD, Confidor® 200 OD and Mospilan® 20 SP were applied to the spiders under laboratory conditions and their effect was tested at different concentrations and different methods of application. The biggest impact on spiders had Confidor. It clearly had the most significant negative effect on mobility and a tendency to spider wind propagation. The lethal effects were caused by neonicotinoids in nymphal individuals Pardosa lugubris, especially Confidor (even 100% mortality for tarsal application). During an experiment studying the...

Orb-weavers (Araneidae) are a diversified spider family comprising more than 3,100 species in more than 170 genera. Together with 13 other families, they con- stitute to superfamily Araneoidea. The presented thesis focuses on karyotype evo- lution of Araneidae, including its comparison with a related family Tetragnathidae. The results obtained from 19 araneid and four tetragnathid species confirm previ- ously postulated hypothesis that the ancestral karyotype of Araneoidea (including Araneidae) consists of 24 acrocentric chromosomes in males, including two acro- centric X chromosomes of system X1X20. However, there is a tendency of 2n decrease in some araneids due to centric fusions. In these cases, centric fusions affected most autosomes (and sometimes gonosomes as well); number of chromosome pairs de- creased from 11 to six. Three independent reduction events were detected in this thesis. Furthermore, pattern of nucleolar organizer regions (NORs) was studied in this thesis using fluorescent in situ hybridization, since data on evolution of this marker are scarce in spiders. Striking variability in NORs number was discovered, ranging from one to 13 loci. Remarkably, multiple centric fusions were always ac- companied by considerable increase of NORs number. In araneids and tetragnathids possessing...

The unifying concept of endosymbiosis and the ‘holobiont’ is that the interaction of the microbial community and the host’s biology can affect myriad processes from speciation to physiology to behavior. This study explored the role of the microbiome as a potential facilitator of rapid evolution of social behavior in a socially polymorphic species of spider, Anelosimus studiosus. Adult females were collected from solitary and social colonies at two geographically distinct locations, and behaviorally assayed to assign individuals to ‘docile’ or ‘aggressive’ phenotypes. Microbiomes of each individual were analyzed by 16s rRNA sequencing. Correlations were found with external influences on the microbiome (colony type, local environmental microbiota, and among colony), and also between the microbiome and individual’s behavioral phenotype. While causation has not yet been established, these data suggest that demographics and ecology affect the microbiome, and that behavior may be affected by the microbiome.

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This thesis provides new insight concerning drivers behind differences in arthropod diversity and abundance in Baltic shore ecosystems and how the arthropod communities might be affected when the conditions in the Baltic Sea are altered due to climate change.  The focus has been on climate related changes that are unique for coastal ecosystems, especially sea level rise and changes in the inflow of marine nutrients. As sea levels rise, features in coastal landscapes will be altered, islands and habitats will be flooded and diminished, and structural connectivity within the island landscape will therefore change. This thesis shows that arthropod diversity within the two arthropod groups, spiders and beetles, increases with island size but also that diversity is positively influenced by a high number of islands in the surroundings. A changed distribution and occurrence of marine species, due to climate change or eutrophication, can also affect terrestrial organisms on the shore.  In the Baltic Sea the new conditions following climate change will decrease the prevalence of bladder-wrack and benefit filamentous algae. Algal deposits on shores reflect the marine species composition and a decreased prevalence of bladder-wrack in the Baltic Sea will also be visible on the shores.  This thesis shows that a lower proportion of bladder-wrack in the algal deposits will decrease the diversity and abundance of arthropods in these deposits. Changes in the marine environment may also affect the inflow of insects with aquatic life stages and terrestrial adult stages.  On Baltic shores, prey species with aquatic life stages, especially chironomids, constitute a large proportion of the diet of the terrestrial predatory group, wolf spiders. In freshwater system, the inflow of chironomids is known to decrease with elevated water temperatures if this is true in the Baltic Sea prey availability of wolf spiders would decrease.  This thesis supports the importance of chironomids as a prey for coastal wolf spiders, but also shows that the diet varies over season with dominance of terrestrial prey in early summer shifting to a dominance of marine prey in late summer and autumn. This seasonal variation is primarily due to a gradual increase in the consumption of chironomids over season. Climate change has the potential to alter the biogeographical conditions in coastal landscapes as well as the density and quality of marine nutrient inflow. Sea level rise will diminish and flood islands and this thesis shows that a moderate sea level rise of 0.5 meters would make the total number of islands in the outer part of Stockholm archipelago decrease with about 25 %. Sea level rise could thus have consequences for arthropod diversity in Baltic shore meadows in the near future. The combined effects of sea level rise and changed prevalence of marine species in the Baltic Sea will affect the abundance and diversity of arthropods substantially. The abundance and diversity of spiders and beetles will decrease on shores that today have a high occurrence of bladder-wrack and prey availability for coastal predators might decrease due to a decreased inflow of chironomids. Changes in the arthropod communities could have consequences also further up in the food chain, such as for shore birds feeding on these arthropods. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>