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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Factors Influencing Avian Habitat Selection between Oak-hickory and Mesic Forests in Southern Illinois

Sierzega, Kevin Paul 01 May 2016 (has links)
Prolific oak regeneration occurred over past centuries from anthropogenic cutting, grazing, and fire, and has declined over the past century due to decreased disturbance. Mesophication within closed-canopy forests of the eastern deciduous region has resulted. Oaks are a keystone species and provide abundant resources for forest wildlife; the ability of late-successional tree species to provide similar resources is relatively understudied. To determine the importance of oak-hickory stands for forest birds, we examined two habitat-selection hypotheses that influence avian abundance and distribution: (1) Habitat heterogeneity (i.e. differences in forest structure) and (2) Availability and distribution of food resources (i.e. index of arthropod biomass). We examined avian response across a gradient of oak-hickory to non-oak tree-species dominance. Non-oak stands were largely dominated by sugar maple, American beech, and yellow poplar (Liriodendron tulipifera). We predicted that migratory breeding-species of concern would respond positively to oak-dominated stands and associated vegetation (e.g. oaks and hickories) because they provide more heterogeneity and likely more food than non-oak stands and associated vegetation (e.g. yellow poplar, maples and beech). We hypothesized that oak and hickory species contain more arthropod biomass and diversity than late-successional species. We conducted breeding bird surveys from 30-April to 15-July 2013-2014 in the Shawnee National Forest, Illinois at 22 study sites. We characterized study sites by dominant canopy vegetation. We used a modified version of the branch-clipping technique to sample arthropods on tree species that represented a gradient of succession. We used generalized linear mixed models to examine differences in arthropod metrics. We estimated detection probabilities for PIF-concern, breeding species and modeled density as response to a priori habitat models using hierarchical distance sampling in R package unmarked. We compared best-fit habitat models for each species with a model of our derived index of food availability (i.e. mean total arthropod biomass (g/m)) for each study site. Habitat heterogeneity was higher in oak-hickory dominated sites. Aerial foragers and foliage gleaners responded predominantly to forest composition and structure, whereas ground foragers responded largely to microhabitat. Density estimates from five of seven species that included percent oak-hickory composition in top models exhibited positive responses. All species that included canopy tree diversity (n=6) in top models responded positively to increasing canopy diversity, and canopy diversity was significantly higher in oak-hickory sites than non-oak sites. Yellow poplar, oak and hickory species yielded more total arthropod biomass (g/m), Lepidopteran biomass (g/m), and guild diversity and richness than late-successional beech and maples. Heterogeneity and food biomass both influenced avian abundance of aerial foragers and foliage gleaners. Our results imply that oak-hickory stands are ecologically important for migratory forest birds of concern because heterogeneity and food resources increase as oak-hickory canopy composition increases. Oak regeneration is a challenging process to manage because oaks require frequent disturbance to achieve the high levels of light needed by this genus. Therefore, it may be beneficial to manage stands for yellow poplar dominance because this species grows rapidly. Moreover, our results suggest that yellow poplar yields comparable and higher estimates of arthropod biomass and diversity on hickories and oaks, respectively. However, foraging opportunities are likely restricted on yellow poplar because of limited structure, attributed to excurrent branching.
22

Genome Size and Endonuclear DNA Replication in Spiders

Rasch, Ellen M., Connelly, Barbara A. 01 August 2005 (has links)
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.
23

A Multi-Taxonomic Approach to Assess the Impact of Overabundant White-Tailed Deer (Odocoileus virginianus) in Forest Ecosystems Across Northeast Ohio

Laux, Sara Ann 03 June 2013 (has links)
No description available.
24

Evolution and taxonomy of Cambrian arthropods from Greenland and Sweden

Stein, Martin January 2008 (has links)
<p>Arthropods have a rich fossil record spanning the Phanerozoic. Biomineralized forms such as the extinct trilobites are particularly common and are proven index fossils for biostratigraphy. Forms with an unmineralized cuticle are more rare, preserved only in so called <i>konservat lagerstätten</i>. Cambrian strata of Greenland have yielded rich trilobite faunas with potential for intercontinental correlation of Cambrian strata, but also an exceptionally preserved fauna, the Sirius Passet Lagerstätte. The first part of this thesis is concerned with trilobite biotratigraphy of the provisional Cambrian Series 2 in Greenland. The second part is concerned with exceptionally preserved arthropods from the Sirius Passet Lagerstätte, but also from 'Orsten' deposits from the Cambrian of Sweden.</p><p><i>Perissopyge phenax occurs</i> in the Henson Gletscher and Paralleldal formations spanning the Series 2 and 3 boundary interval in North Greenland. It also occurs in the Sekwi Formation of Yukon Territory, demonstrating that the species may hold potential for correlation within Laurentia. An indeterminate species of <i>Perissopyge</i> is shown to occur in the Ella Island Formation of North-East Greenland together with <i>Olenellus</i> cf. <i>hanseni</i>, which is similar to <i>Olenellus</i> cf. <i>truemani</i> described from the Henson Gletscher Formation. If this correlation is further corroborated it would offer a first tie-point for the An t'Sron Formation of North-West Scotland which yields <i>Fritzolenellus</i> <i>lapworthi</i>, herein reported for the first time from the Bastion Formation which underlies the Ella Island Formation.</p><p><i>Oelandocaris</i> <i>oelandica</i> from ‘Orsten’ deposits in the Cambrian series 3 and 4 boundary interval in Sweden is an early representative of the Crustacean stem lineage. <i>Kiisortoqia</i> <i>avannaarsuensis</i> is a new arthropod from the Sirius Passet Lagerstätte with robust antennulae strikingly similar to the 'raptorial' limb of the problematic anomalocaridids. The ventral morphology of the 'bivalved' <i>Isoxys</i> <i>volucris</i> is described for the first time and compared with other species assigned to <i>Isoxys</i> from Cambrian lagerstätten around the world. Finally, <i>Siriocaris</i> <i>trolla</i>, is a new arthropod that similarities with trilobites and certain ‘trilobitomorphs’ but seems to lack important synapomorphies of these taxa, though this may be due to preservational limitations in the material at hand.</p>
25

The efficacy and non-target impacts of an organic disease management system containing biostimulants compared with two sulfur-based systems on four apple cultivars in Vermont

Hazelrigg, Ann L. 01 January 2015 (has links)
Disease management in organic apple orchards in Vermont is focused on controlling diseases with sulfur fungicides. The objective of this two year study was to evaluate the target and non-target effects of an organic disease management system containing agricultural biostimulants compared to two sulfur-based systems on foliar and fruit diseases, pest and beneficial arthropods, tree growth, yield and fruit quality on four cultivars, `Ginger Gold', `Honeycrisp' and `Liberty' and `Zestar!'. Trees were arranged in a complete randomized design of five three-tree replications in a certified organic orchard. The two sulfur-based systems differed in the number of applications; in the third system, sulfur was replaced with biostimulants including pure neem oil, liquid fish, an activated microbial inoculant plus equisetum and stinging nettle teas. Each biostimulant application also included kelp meal, unsulfured organic molasses and yucca extract emulsifier. The biostimulant system did not successfully manage apple scab and rust diseases as well as the sulfur-based fungicide systems, and had variable results with other diseases. No differences were observed among the three systems in tree growth parameters; however, the length of the study may not have been sufficient to determine effects. Differences in the incidence of disease among the three systems were reflected in extrapolated figures for gross income per hectare which takes into account fruit yield and quality. In the higher fruit-bearing year of the study, it was estimated that the gross income per hectare of the biostimulant system would be significantly lower than the reduced-sulfur system and the full-sulfur system by at least $5,800 and $12,000, respectively. In that same year, it is estimated that the full-sulfur system would have generated approximately $6,500 more gross income per hectare than the reduced-sulfur system suggesting the number of sulfur sprays can influence fruit quality and income. The use of the agricultural biostimulants had very limited non-target effects and when present, they were beneficial in suppressing insect pest incidence and/or damage on foliage compared to one or both of the sulfur-based fungicide systems. However, many insect pests or their damage were not observed on the foliage or had incidence of less than 1% in any of the systems. The biostimulant system did appear to suppress European red mites in both years compared to both sulfur-based systems when data were averaged across cultivars. On fruit, no differences in non-target impacts on arthropod pests were observed among the three systems except for surface-feeding Lepidoptera and San Jose scale damage. In a separate phytophagous mite study on the cultivar `Zestar!' leaf samples were evaluated for the number of motile phytophagous mites every 14 days from 1 July through 26 August each year. When there were differences, the biostimulant system had less mite incidence per leaf than one or both of the sulfur-based systems in both years. The difference in the number of sulfur sprays did not have a major effect on the mite populations. In summary, the use of the biostimulant system resulted in insufficient disease management which led to lower estimated gross income compared to the sulfur-based systems. These results show more research and further evaluation of new organic disease management tools, including the use of agricultural biostimulants, are necessary before growers consider replacing the use of standard sulfur fungicides for disease management in Vermont orchards.
26

Savoirs, affectivité et comportements : articulation de trois dimensions pour comprendre comment se construisent les apprentissages dans le contexte de l'éducation à la biodiversité : le cas de l'étude d'arthropodes à l'école primaire en France / Knowledges, emotions and behaviors : articulating three dimensions for understanding learning construction in the context of biodiversity educationThe case study of arthropods in primary school in France

Franc, Serge 13 July 2012 (has links)
En France, l'éducation à la biodiversité est devenue une priorité au regard de la dégradation de la diversité biologique. À l'école primaire, elle est rattachée à la fois aux disciplines scientifiques et au développement durable. Les apprentissages attendus suivent essentiellement deux dimensions : les savoirs bio-écologiques et les comportements escomptés reliés à ces savoirs. Cependant, de nombreuses recherches font apparaître l'importance de la dimension affective dans ces apprentissages notamment au regard du rapport émotionnel entretenu avec les objets d'étude. Dans ce contexte, cette thèse explore les dimensions cognitive, affective et comportementale des apprentissages en éducation à la biodiversité. Le champ de recherche est restreint à l'étude d'arthropodes à l'école primaire. Comment la description et l'analyse de trois dimensions : savoir, affectivité et comportements permettent-elles de comprendre la construction des apprentissages en éducation à la biodiversité dans le cas de l'étude d'arthropodes à l'école primaire ? Pour répondre à cette question, le cadre conceptuel s'appuie sur l'analyse des savoirs, sur le modèle de la maturité affective vis-à-vis des objets étudiés et sur l'opérationalisation des comportements par les prises de position et intentions d'agir. Quatre objectifs sont poursuivis pour répondre à cette question : décrire et analyser chacune des trois dimensions, dégager les corrélations éventuelles entre les trois dimensions, identifier des profils particuliers d'apprenants, vérifier les effets d'une étude des arthropodes sur les apprentissages selon ces trois dimensions. La méthodologie utilisée suit deux perspectives : quantitative par une analyse multivariée des réponses à un questionnaire et qualitative par une analyse de réponses à la suite d'entretiens semi-dirigés. Les résultats obtenus ont permis de clarifier les trois dimensions considérées et d'éclairer leur articulation. La mesure et l'analyse de chaque dimension ont montré des différences significatives en fonction du type d'enseignement reçu en classe. Entre les dimensions analysées il existe des corrélations remarquables entre les savoirs, la maturité affective et les comportements. Des profils particuliers d'apprenants inter-reliant savoirs et affectivité ont pu être identifiés, ainsi que des profils généraux impliquant les trois dimensions. Nous avons pu constater l'importance de la relation affective avec les objets d'apprentissage qui, loin de perturber l'appropriation des savoirs aurait au contraire tendance à les renforcer tout en contribuant à construire des comportements citoyens et responsables. / In France, biodiversity education appears as a priority linked with the degradation of biodiversity. The biodiversity education in primary school is attached to both the scientific topics and sustainable development. The expected learning follows two basic dimensions: bio-ecological knowledges and behaviors related to the expected knowledges. However, numerous studies show the significance of affective dimension in learning, especially regarding the emotional relationship with the objects of study. In this context, this thesis explores the cognitive, affective and behavioral learning in biodiversity education. The search field is restricted to the study of arthropods in primary school. How the description and analysis of three dimensions: knowledge, emotions and behaviors allow to understand construction of learning in biodiversity education in the case of the study of arthropods in elementary school? To answer this question, conceptual framework is based on the analysis of knowledges, on the model of emotional maturity with the studied objects and the operationalization of behavior by positions and intentions to act. Four aims are proceeded to answer this issue: describe and analyze each of the three dimensions in the context of the study of arthropods in classroom, identify possible correlations between these three dimensions, identify specific patterns of learners and verify the effects of a study of arthropods on learning, according to these three dimensions. The methodology follows two perspectives: a quantitative multivariate analysis of survey responses and a qualitative analysis of answers during semi-structured interviews. The results of this study have clarified the three-dimensional knowledge, emotions and behaviors and highlighted the interplay between their relations. The measurement and analysis of each dimension pointed significant differences depending on the type of instruction received in classroom. There are significant correlations between scientific knowledge, emotional maturity and behavior according to the type of education. Specific profiles of learners linking knowledges and emotions have been identified, as well as general patterns involving the three dimensions. We noted the importance of emotional relationship with the learning objects that, instead of disrupting the knowledge, would rather tend to strengthen them while contributing to build citizenship and responsible behavior.
27

Arthropod Abundance and Diversity in Restored Longleaf Pine Savannas at Abita Creek Flatwoods Preserve

Nighohossian, Cara B 16 May 2014 (has links)
The objective of this study is to determine whether changes in arthropod community structure in restored longleaf pine savannas corresponds to differences in vegetation structure often associated with burn frequency. Longleaf pine savannas are fire-maintained ecosystems characteristic of the southeastern United States and have experienced severe declines (around 97%) since European settlement. Changes in fire regime have been instrumental in the declines. Restoration of these ecosystems has involved reinstitution of periodic burnings to promote and maintain vegetative characteristics of the savannas. This study investigates trends in arthropod communities from areas heavily invaded by hardwood shrubs against those dominated by longleaf pines and associated vegetation. These data suggest that herb-dominated sites have higher overall diversity. While overall abundance differences were not found, significant differences have been detected at the order and family level, indicating that vegetation structure and periodic burning are important factors in maintaining arthropod communities characteristic of these savannas.
28

Interakce rostlin a hmyzu ve spodním miocénu střední Evropy v paleoklimatologických a paleoekologických souvislostech / Plant - insect interactions in lower Miocene of Central Europe: palaeoclimatological and palaeoecological implications

Knor, Stanislav January 2015 (has links)
The paleoecology of plant - arthropod herbivory associations constitute very important source of knowledge about the phylogeny and co-evolution of both groups. The traces of herbivory interactions between plants and arthropods on the fossil leaves are preserved as so called damaged types (DTs) clustered into distinct functional feeding groups (FFGs). The diversity and frequency of these damage traces also seem to have been strongly influenced by environmental and climatic conditions. This research has been focused on rich fossil plant assemblages from the area of the Most Basin in the north-western Bohemia. The undergoing work has comprised the diagnosis of the individual damages on the basis of their specific morphological traits as their number, size, shape and distributional pattern on the leaf surface. The next issue has involved the statistical analyses concerning the differences in the frequency and diversity of the types of damage and functional feeding groups between two separate fossiliferous layers, namely those of the stratigraphically older Bílina Delta and younger Břešťany Clay. Significant differences were confirmed in this regard, especially in connection with achieved frequency and proportional occurrences of distinct functional feeding groups in the Bílina Delta. The galls were the...
29

Identification des arthropodes et pathogènes associés par MALDI-TOF MS et étude des relations entre arthropodes et bactéries / Identification of arthropods and associated pathogens by MALDI-TOF MS and study of the relationship between arthropods and bacteria

El Hamzaoui, Basma 22 November 2018 (has links)
Ce travail est composé de 3 parties. La première est une étude épidémiologique avec la détection moléculaire des spécimens appartenant à six espèces d’Argasidés collectées en Algérie et identifiées morphologiquement et par biologie moléculaire. Nous avons pu détecter Borrelia hispanica dans des Ornithodoros occidentalis et Borrelia cf turicatae dans des Carios Carpensis. Dans des Argas persicus nous avons pu identifier un nouveau génotype de Bartonella spp ainsi qu’un génotype appartenant à une nouvelle espèce dans la famille des Anaplasmataceae. Dans la 2e partie, nous avons évalué la capacité vectorielle des punaises de lit à transmettre Borrelia recurrentis, l’agent de la fièvre récurrente. Pour ce fait, nous avons utilisé un modèle expérimental d’infection artificielle de Cimex lectularius par B. recurrentis pour ensuite détecter la présence de la bactérie dans les fèces. Nous avons utilisé quatre approches : la détection par qPCR, la culture à partir des fèces, la FDA (Fluorescein Diacetate) et l’inoculation des fèces aux souris. Nous avons également utilisé l’Immunofluorescence pour localiser la bactérie dans le corps de la punaise. Nous avons constaté que les punaises de lit acquièrent la bactérie et excrètent des microorganismes vivants dans les fèces. Elles peuvent être considérées comme vecteur potentiel de Borrelia recurrentis. La troisième partie s’intéresse à l’évaluation de la capacité du MALDI-TOF MS à identifier les puces, les punaises et les pathogènes associés. / This work focuses on three main parts, a first part presents an epidemiological study of bacteria associated with soft ticks in Algeria, or we identified morphologically and confirmed by molecular biology six species of Argasidae. In addition, looking further we could detect Borrelia hispanica in Ornithodoros occidentalis and Borrelia cf turicatae in Carios Carpensis. On the other hand, in Argas persicus a new genotype of Bartonella spp has been identified as well as a new species of Anaplasmatacea bacteria.A second part evaluates the vectorial capacity of bed bugs to transmit Borrelia recurrentis, the agent of the relapsing fever. For this reason an experimental model of artificial infection of Cimex lectularius by Borrelia recurrentis has been developed, to study the presence of bacteria in feces. In this model, four approaches were used: qPCR, fece’s culture, FDA (Fluorescein Diacetate) and fece’s inoculation to mice. Immunofluorescence was also used to detect the location of the bacteria in the body of the bed bug. We confirmed that bed bugs acquire the bacteria and excrete live microorganisms in the feces. They can be considered as potential vector of Borrelia recurrentis.The third part is an assessment of the capacity of MALDI-TOF MS to identified fleas, bed bugs and associated pathogens. This innovative tool, which has revolutionized medical entomology and has shown its efficiency to identify several species of arthropods, has also been able to distinguish between infected and uninfected fleas and bugs, and even distinguish between fleas and bugs infected by the same species of bacteria.
30

"Artrópodos e suas relações de herbivoria como bioindicadores nos primeiros estágios de uma recomposição de floresta estacional semidecidual em Ribeirão Preto, SP". / Arthropods and its herbivory relationships as bioindicators in the first stages after restoration of a semideciduous estational forest area

Pais, Mara Patrícia 11 July 2003 (has links)
Em 1998 iniciou-se no campus da USP de Ribeirão Preto, SP, um projeto recuperação florestal entitulado "Floresta da USP", com o propósito de recompor,numa área de 75 ha, a floresta estacional semidecidual, um dos tipos de vegetação nativa da região. O presente estudo teve como objetivo avaliar as principais modificações que se processam neste novo habitat nos primeiros anos seguidos ao plantio, utilizando a comunidade de artrópodos e as relações de herbivoria como bioindicadores. Inicialmente, foram avaliados alguns parâmetros da estrutura do habitat em quatro sub-áreas com idades diferentes, comparando-as com um remanescente de floresta nativa existente nas proximidades. Entre estes mesmos locais, foi comparada a comunidade de artrópodos epígeos através de análise multivariada, buscando relacioná-las com variáveis ambientais. Além disso, numa das áreas foi acompanhada a dinâmica da comunidade de artrópodos associada à seis espécies vegetais (três pioneiras e três tardias), por dois anos consecutivos. Nas mesmas espécies vegetais utilizadas para a amostragem de artrópodos, foram avaliados os níveis de herbivoria e algumas características vegetais que poderiam influenciar na preferência por insetos herbívoros. Ficou demonstrado que as maiores transformações do habitat recomposto ocorrem nos dois primeiros anos seguidos ao plantio. As principais variáveis do habitat relacionadas com a fauna de artrópodos epígeos foram a altura da vegetação, presença de gramíneas invasoras e presença de um terceiro estrato arbóreo, exclusivo da mata nativa. Apesar de muito dissimilares da comunidade da mata, as comunidades das sub-áreas da Floresta da USP mostram uma tendência de se aproximarem da existente na mata de acordo com o tempo transcorrido após o plantio. Em relação à fauna de dossel, embora não se tenha observado diferença na riqueza, abundância e diversidade geral entre os dois anos seguidos ao plantio, foi detectada uma grande dissimilaridade de espécies e uma profunda reestruturação da abundância de organismos dentro das guildas. As formigas, tanto por sua abundância como riqueza, tiveram grande participação dentro das diversas variáveis da comunidade analisadas e, entre elas, as formigas cortadeiras foram também responsáveis por uma grande elevação nos níveis de herbivoria do primeiro para o segundo ano de acompanhamento, tanto em espécies iniciais quanto tardias. / In 1998 a recomposition project named "Floresta da USP" was started at the USP campus in Ribeirão Preto, SP, aiming at recovering a 75 ha area with the regional native vegetation, the seasonal semideciduous forest. This study evaluated the main changes that ocurried in this new habitat during the first years after planting, considering the arthropod community and the herbivory relationships as bioindicators. We measured some habitat structure parameters at four sites of different ages, contrasting them to the same parameters measured at a local forest patch. The epigeous arthropod community was compared among sites using multivariate analysis, including several environmental variables. We also monitored the community dynamics of arthropods, herbivory levels and leaf physical chemical caracteristics of six plant species (3 pioneers and 3 late successional) at one of the sites during two years as well as the main leaf variables that could have some effect on the herbivore preferences. Results indicated great chances in the first years of recomposition. Vegetation height, presence of alien grasses, and presence of a third stratum at the forest patch were the principal habitat features related to the epigeous arthropod community. Despite the high dissimilarity, arthropod community of recomposed sites had a tendency of reducing this dissimilarity over time in relation to the forest. Richness, abundance, and diversity of canopy arthropod community were not different between the two years. However, a high species dissimilarity was detected and a strong guild rearrangement concerning abundance from one year to another. There was a high number of species and individuals. Leaf-cutting ants were important to the ecosystem dynamics due to the high levels of herbivory imposed to several plant species.

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