Spiders belong to one of the most important natural pest antagonists in many agroecosystems. The species diversity and abundance of spiders, hence their biocontrol potential, is directly related and is often increased by the presence of non-agricultural, non-productive areas in the landscape directly surrounded with agroecosystems. My research was focused on spiders related to the vine plats trunks, first of all as organisms reflecting the function of vineyard terraces in relation to increasing their heterogeneity, which in turn reflects on the resulting biodiversity of the landscape, and secondly as pest antagonists in vineyards, which can effectively and nature-friendly contribute to the sustainability of agricultural units. Research areas in the South Moravian Region were selected and species diversity and spider abundance were analyzed. Two vineyards at each site have been selected: classic - plain vineyards and terraced vineyards which were lined with non-productive slopes. From November 2013 to October 2014, 727 adult spiders belonging to 21 species and 7 families were recorded. Concerning the vulnerability of each species, 12 abundant species were found, 4 species were almost threatened, 3 were endangered species, 1 species was strongly endangered, and 1 species was critically endangered. According to the results, we can state that the species spectrum of spiders found on vine plant trunks may in the future function as a biocontrolling agent and may have an interesting influence on vine pests.

Until the second half of the 20th century, the Czech landscape was traditionally maintained by traditional farming and grazing that produced a heterogeneous mosaic of microhabitats. However, the abandonment of traditional farming caused the areas with early stages of succession to overgrow and become homogeneous, resulting in the serious loss of arthropod biodiversity. This traditional farming therefore needs to be replaced by an active conservation management method. This Master thesis studies the effect of conservation management on the arachnofauna of the steppe biotopes Pláně Nature Monument. Specifically, the influence of disturbance, mowing, prescribed burning, and non-intervention on abundance, species richness, occurrence of rare and endangered species and species and functional composition of spiders was investigated. Spider sampling was carried out using pitfall traps and sweeping during the whole season in 2017 and 2018. The treatments were applied on the patches (4 x 5 m) and replicated at three sites. A total of 154 species with 11,634 specimens including many rare and endangered spider species were captured. Management had no significant effect on the abundance and species richness of epigeic spiders. Herb-dwelling spiders had high abundance and high species richness in control and burned patches. Burned patches had high values of conservation indicators, where the significant proportion of xerothermic species and hunting guilds were represented. Intensive disturbance had rather a negative effect on the overall arachnofauna. Prescribed burning had positive results for most of the studied indicators. The results show that interventions performed on a small area can significantly support the valuable arachnofauna of steppe habitats. To support habitat heterogeneity and the diversity of organisms that depend on it, the interventions should be combined and performed in such a scale that would avoid extensive habitat disturbance.

Many animal societies rely on highly influential keystone individuals for proper functioning. When information quality is important for group success, such keystone individuals have the potential to diminish group performance if they possess inaccurate information. Here, we test whether information quality (accurate or inaccurate) influences collective outcomes when keystone individuals are the first to acquire it. We trained keystone or generic individuals to attack or avoid novel stimuli and implanted these trained individuals within groups of naive colony-mates. We subsequently tracked how quickly groups learned about their environment in situations that matched (accurate information) or mismatched (inaccurate information) the training of the trained individual. We found that colonies with just one accurately informed individual were quicker to learn to attack a novel prey stimulus than colonies with no informed individuals. However, this effect was no more pronounced when the informed individual was a keystone individual. In contrast, keystones with inaccurate information had larger effects than generic individuals with identical information: groups containing keystones with inaccurate information took longer to learn to attack/avoid prey/predator stimuli and gained less weight than groups harbouring generic individuals with identical information. Our results convey that misinformed keystone individuals can become points of vulnerability for their societies.

Although genome sizes (C-values) are now available for 115 arachnid species (Gregory and Shorthouse [2003] J Hered 94:285-290), the extent of genome amplification (endonuclear DNA replication or polyploidization) accompanying tissue differentiation in this diverse and abundant class of invertebrates remains unknown. To explore this aspect of arachnid development, samples of hemolymph and other tissues were taken from wild-caught specimens as air-dried smears, stained with the Feulgen reaction for DNA, and assayed using both scanning and image analysis densitometry. Cells from midgut diverticula and Malpighian tubules of Argiope and Lycosa (=Pardosa) often showed giant nuclei with 50-100 pg of DNA per nucleus, reflecting at least four cycles of endonuclear DNA replication when compared to the DNA content of hemocytes or sperm from the same specimen. Nuclei with markedly elevated DNA levels also appeared, but far less frequently, in tissue samples from several other arachnid species (Antrodiaetus, Hypochilus, Latrodectus, Liphistus and Loxosceles), but revealed no correlation with differences in somatic cell (2C) genome sizes. Our data show that several DNA classes of polysomatic nuclei regularly arise during tissue differentiation in some species of spiders and may provide an interesting model system for further study of patterns of tissue-specific variation in DNA endoreduplication during development.

Twenty-first-century globalization has led to an extraordinary rise in international trade and transit. Consequentially, invertebrates, plants, and mammals are displaced more frequently, which has catalyzed a historic rise in biological invasions. The Joro Spider (Araneae: Trichonephila clavata) recently established from Asia in a landlocked region of southern Appalachia. Its range continues to expand; its cold tolerance is expected to favor northward invasion. As a large-bodied orbweaver that forms extensive webs and aggregations, the Joro spider is likely capable of inducing fundamental change to community structure via spatial competition. A valuable first step in estimating any invader’s economic or biological impact is to hypothesize regions susceptible to invasion using species distribution models. Recent work also shows that comparing global and regional distribution models yields insight into different stages of invasion. To examine potential spread and niche utilization differences in the Joro spider, one global and two regional models were developed. Maximum Entropy models were trained using open-source citizen science occurrence data and six bioclimatic variables at 2.5-arcminute resolution. An AUC-weighted ensemble model was used to produce each of the 3 global suitability projections. To compare invasive stage differences, projections were then translated to presence-absence maps using a 50% suitability threshold. The Asia-regional model predicts widespread suitability in eastern North America. However, the US-regional model reflects local adaptation to a climate niche that does not occur in the spider’s historic Asian range. Permutation feature importance shows the US-regional model was driven mainly by precipitation seasonality (64%) and annual oscillations in daily temperature range (29.1%). The Asia-regional model was instead driven by mean temperature of the driest quarter (34.9%), maximum temperature of the warmest month (23.6%), and precipitation of the warmest quarter (20.1%). The introduced Joro spider has invaded a North American niche that it is naïve to, but which co-occurs spatially with a niche akin to its historic Asian niche. If the Asia-regional climatic niche is indeed exploitable in North America, then conservative estimates show the bounds of range suitability should approach the 95th meridian and the 28th and 50th parallels. A total of 1,231,711 km2 within North America was predicted above 50% suitability. Altogether, these findings suggest niche versatility and plentiful suitable habitat favors successful North American invasion by the Joro spider.

Made available in DSpace on 2014-12-17T14:33:11Z (GMT). No. of bitstreams: 1 NicholasSAA_DISSERT.pdf: 1948030 bytes, checksum: 80dfd0f7427129fc2bc508e3309bfdb3 (MD5) Previous issue date: 2013-08-28 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The inherent complexity of natural communities is a challenge to our understanding about how the habitat influences the abundance, local distribution and species diversity. The habitat can influence community structure in multiple ways and elucidate these relationships has provoked a lot of debate in ecology. The habitat heterogeneity hypothesis states that an increase in habitat heterogeneity (number of habitats) leads to an increase in species diversity in the landscape due to an expansion in niche dimensions. This study aims to identify whether this hypothesis is valid for the spiders that inhabit a locality in the Caatinga of northeastern Brazil. Cursorial and arboreal spiders were sampled in 30 plots within an area of Caatinga together with measures of environmental complexity, habitat heterogeneity and environmental parameters related to multiple aspects of vegetation architecture and species composition of woody plants. Stepwise multiple regressions were used to define which local environmental parameters best explain the variation in arboreal and cursorial spiders richness. Then a NMDS (Nonmetric multidimensional scaling) was used to reduce the number of predictive variables to those who are the most important and best represent the variation in spiders richness associated with the environment they were sampled. The results show a clear segregation between the guilds of arboreal and cursorial spiders, both related to what kind of environmental variables best explain its variation as well as in relation to what part of the vegetation they occupy / A complexidade inerente as comunidades naturais desafia nosso entendimento sobre como o habitat influencia a abund?ncia, a distribui??o local e a diversidade das esp?cies. O habitat pode influenciar a estrutura das comunidades de m?ltiplas maneiras e elucidar essas rela??es tem sido um tema de intenso debate na ecologia. A hip?tese de heterogeneidade de habitat afirma que um aumento na complexidade do ambiente leva a uma maior disponibilidade no n?mero de habitas que, por conseq??ncia, leva a uma amplia??o na diversidade de esp?cies na paisagem devido a uma expans?o no n?mero de parti??es das dimens?es do nicho. O presente trabalho visa identificar se essa hip?tese ? v?lida para as aranhas que habitam uma localidade na Caatinga do nordeste brasileiro. Para isso, aranhas cursoriais e arbor?colas foram amostradas em 30 parcelas dentro de uma ?rea de Caatinga, paralelamente a tomada de medidas de complexidade ambiental, heterogeneidade de habitat e par?metros do ambiente, relacionadas com m?ltiplos aspectos da arquitetura da vegeta??o e composi??o das esp?cies de plantas lenhosas. Regress?es m?ltiplas do tipo Stepwise foram utilizadas para medir que par?metros ambientais locais melhor explicam a varia??o na riqueza de aranhas arbor?colas e cursoriais. Em seguida, um NMDS (Nonmetric multidimensional scaling) foi utilizado para reduzir o n?mero de vari?veis preditoras ?quelas mais importantes e que melhor representavam a varia??o na riqueza de aranhas associada ao ambiente que foram amostradas. Os resultados apontam uma segrega??o evidente entre as guildas de aranhas arbor?colas e cursoriais, tanto relacionada a que tipo de vari?veis ambientais melhor explicam sua varia??o assim como em rela??o ao extrato da vegeta??o que esses organismos ocupam

Submitted by Irvana Coutinho (irvana@ufpa.br) on 2017-05-04T12:49:34Z No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Parte1NovasEspeciesGenero.pdf: 906488 bytes, checksum: 7665a9f17692161a1003a82b29b7e20f (MD5) Dissertacao_Parte2_PranchasNeoxyphinus.pdf: 16578737 bytes, checksum: 301688f97aa2aa26bab0a9188f235d1a (MD5) / Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2017-05-04T12:50:30Z (GMT) No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Parte1NovasEspeciesGenero.pdf: 906488 bytes, checksum: 7665a9f17692161a1003a82b29b7e20f (MD5) Dissertacao_Parte2_PranchasNeoxyphinus.pdf: 16578737 bytes, checksum: 301688f97aa2aa26bab0a9188f235d1a (MD5) / Made available in DSpace on 2017-05-04T12:50:30Z (GMT). No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Parte1NovasEspeciesGenero.pdf: 906488 bytes, checksum: 7665a9f17692161a1003a82b29b7e20f (MD5) Dissertacao_Parte2_PranchasNeoxyphinus.pdf: 16578737 bytes, checksum: 301688f97aa2aa26bab0a9188f235d1a (MD5) Previous issue date: 2016-02-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Um total de 27 novas espécies do gênero Neoxyphinus são descritas, todas ocorrendo em território Brasileiro, elevando o número total de espécies do gênero para 48. As novas espécies são listadas a seguir, com a respectiva distribuição geográfica e sexos descritos: N. capiranga sp. nov. (♂♀) do Amazonas, Pará, Mato Grosso e Rondônia; N. caprichoso sp. nov. (♂♀) e N. garantido sp. nov. (♂♀) do Amazonas e Pará; N. crasto sp. nov. (♂♀) da Bahia e Sergipe; N. murici sp. nov. (♂♀) de Alagoas e Sergipe; N. meurei sp. nov. (♀) da Bahia e Mato Grosso; N. belterra sp. nov. (♂♀) do Pará e Mato Grosso; N. ornithogoblin sp. nov. (♂♀), N. sax sp. nov. (♂♀), N. coari sp. nov. (♂♀), N. tucuma sp. nov. (♂♀), N. ducke sp. nov. (♂) e N. carigoglin sp. nov. (♀) do Amazonas; N. almerim sp. nov. (♂), N. mutum sp. nov. (♂♀), N. caxiuana sp. nov. (♂♀), N. cachimbo sp. nov. (♂) e N. jacareacanga sp. nov. (♀) do Pará; N. paraty sp. nov. (♂♀) e N. rio sp. nov. (♂♀) do Rio de Janeiro; N. novalima sp. nov. (♂♀) e N. celluliticus sp. nov. (♂) de Minas Gerais; N. paraiba sp. nov. (♂) e N. simsinho sp. nov. (♂♀) da Paraíba; N. cantareira sp. nov. (♂) de São Paulo; N. cavus sp. nov. (♂) do Espírito Santo e N. stigmatus sp. nov. (♂) da Bahia. Uma chave para identificação de todas as 48 espécies conhecidas de Neoxyphinus é fornecida e possíveis linhagens monofiléticas dentro do gênero são discutidas. / Twenty-seven new species of the genus Neoxyphinus are described, all from Brazil, are described, rising the total number of species of the genus to 48. The new species with the respective geographic distribution and known sexes are: N. capiranga sp. nov. (♂♀) from Amazonas, Pará, Mato Grosso and Rondônia; N. caprichoso sp. nov. (♂♀) and N. garantido sp. nov. (♂♀) from Amazonas and Pará; N. crasto sp. nov. (♂♀) from Bahia and Sergipe; N. murici sp. nov. (♂♀ from Alagoas and Sergipe; N. meurei sp. nov. (♀) from Bahia and Mato Grosso; N. belterra sp. nov. (♂♀) from Pará and Mato Grosso; N. ornithogoblin sp. nov. (♂♀), N. sax sp. nov. (♂♀), N. coari sp. nov. (♂♀), N. tucuma sp. nov. (♂♀), N. ducke sp. nov. (♂) and N. carigoblin sp. nov. (♀) from Amazonas; N. almerim sp. nov. (♂), N. mutum sp. nov. (♂♀), N. caxiuana sp. nov. (♂♀), N. cachimbo sp. nov. (♂) and N. jacareacanga sp. nov. (♀) from Pará; N. paraty sp. nov. (♂♀) and N. rio sp. nov. (♂♀) from Rio de Janeiro; N. novalima sp. nov. (♂♀) and N. celluliticus sp. nov. (♂) from Minas Gerais; N. paraiba sp. nov. (♂) and N. simsinho sp. nov. (♂♀) from Paraíba; N. cantareira sp. nov. (♂) from São Paulo; N. cavus sp. nov. (♂) from Espírito Santo and N. stigmatus sp. nov. (♂) from Bahia. A key for identification of all 48 known species of Neoxyphinus is provided and possible monophyletic lineages within the genus are discussed.

Spiders are host to a plethora of heritable endosymbiotic bacteria. Broad-taxa screening studies indicate that endosymbionts are particularly common among spiders, however, little is known about how these bacteria affect their spider hosts. In insects these bacteria ensure vertical transmission by either conveying a benefit to the host or manipulating host reproduction to eliminate males that serve as evolutionary dead-ends for maternally-inherited bacteria. Common modes of reproductive manipulation include parthenogenesis, male killing, feminization, and cytoplasmic incompatibility. Screening an assemblage of Mermessus genus spiders, I detected a high frequency and diversity of endosymbiont infection. Within a single species, M. fradeorum, I detected three endosymbionts in multiple combinations. Rearing two natural infection types of M. fradeorum demonstrated two distinct endosymbiotic reproductive manipulations. Mothers infected with Rickettsia and Wolbachia produced extremely female-biased offspring, and antibiotic elimination of the symbionts successfully restored the sex ratio to the expected 1:1 in subsequent generations. A two-way factorial mating assay detected strong cytoplasmic incompatibility induced by a different strain of Wolbachia: cured females mated with infected males produced 70% fewer offspring than all other pairings. These results show that M. fradeorum is subject to multiple layers of reproductive manipulation that likely drive host evolution and ecology.

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.

Successional changes occurring in the structure and composition of communities of epigeic fauna in the first three (Coleoptera: Carabidae), or two (Araneae) years after the pine stands fire have been studied since 2013 in the territory of the Moravian Sahara (Bzenec, Czech Republic). 11 permanent research plots were established in order to evaluate the response of epigeic fauna and habitat changes after the fire. These included areas deforested after the fire, pine stands severely affected by the fire (27 years) left to natural successional development and pine stands (94 years) with ongoing salvage cutting. Qualitatively equal stands undisturbed by the fire (29 and 78 years) were simultaneously studied. Pitfall traps were used (5 pcs/area) to determine the state of the epigeic fauna. A total of 90 kinds of Carabid species and 151 spider species were caught and determined. The structure and composition of ground beetle and spider communities in locations disturbed and undisturbed by fire differed throughout the observation period. Ground beetle and spider communities of biotopes undisturbed by the fire showed a stable structure and community composition, while in pine stands disturbed by the fire, a gradual increase in species dominance and diversity of heliophilous and xerophilous groups took place. A significant decline in the species diversity of spiders in pine stands disturbed by fire was recorded between 2013 and 2014. Ground beetle communities showed the opposite trend. Ground beetle and spider communities in the surveyed area demonstrated a sensitive link to a change in the microclimatic conditions of the studied habitats; on the basis of changes in their composition, it was therefore possible to infer changes taking place also in the stands, where the effects of fire were not apparent at first glance.