Cette thèse a visé à comprendre et à recréer artificiellement un mécanisme d'auto-assemblage présent dans la soie d'araignée. Les gouttes de glue microniques qui existent sur la soie d'araignée dîte de capture servent à fournir à la toile ses propriétés adhésives. Ces gouttes jouent pourtant un autre rôle : elles améliorent grandement les propriétés mécaniques de la soie, et permettent de préserver l'intégrité structurelle de la toile. La localisation de l'instabilité de flambage au sein des gouttes de glue, site de surcompression par les ménisques capillaire, implique que ce système de gouttes sur fibre se comporte sous compression comme un liquide, alors que sous tension il possède un régime solide. Les araignées ont donc trouvé un moyen de créer des hybrides mécaniques liquide-solide.La première partie de ma thèse fut dédiée à la caractérisation d'échantillons naturels, qui a permis dans la seconde partie de construire un système entièrement artificiel qui reproduit la soie d'araignée de capture, grâce à des microfibres flexibles longues de plusieurs centimètres. Une simple goutte de liquide mouillant permet la création efficace d'un système semblable aux échantillons naturels. La caractérisation fine de ces systèmes de gouttes sur fibre enroulables a mené à un très bon accord entre les résultats expérimentaux, les simulations numériques et une analogie avec les transitions de phase, notamment pour des propriétés telles que le seuil d'activation, l'existence d'une hystérésis ou encore la morphologie de l'enroulement. Ces résultats ont permis la conception de techniques non conventionnelles dans des domaines tels que les méta-matériaux et la micro-fabrication. / This PhD work aimed to understand and recreate artificially a self-assembling mechanism involving capillarity and elasticity present in spider silk. The primary function of the micronic glue droplets that exist on spider capture silk is to provide the spider web with adhesive properties. These droplets play yet another role: the dramatic enhancement of silk mechanical properties, as well as the preservation of the integrity of the web structure. The localization of the buckling instability within the glue droplets, site of over-compression due to the capillary meniscii implies that under compression this special drop-on-fibre system behaves like a liquid, whereas under tension it has a classical elastic spring regime. Spiders have thus found a way to create liquid-solid mechanical hybrids.The first part of my thesis aimed to the characterization of natural samples, which allowed in the second part to build a completely artificial system that mimics the natural samples, through fabrication of centimeter-long micronic soft fibres. The simple addition of a wetting liquid droplet made for an effective system with mechanical properties quantitatively close to that of spider capture silk.Fine characterization of the created drop-on-coilable-fibre systems yielded very good agreement between experimental results and predictions from numerical simulations and a analogy with phase transition, especially for properties such as the threshold for activation, the existence of an hysteresis and the coiling morphology. All those results added up to the design of unconventional techniques in field such as metamaterials and micro-fabrication.

Host-plant resistance is an important component of integrated pest management. Host resistance to phytophagous insects and mites based on chemical and morphological characteristics has been identified in various agronomic crops. The present study was undertaken to examine how variation in selected morphological and chemical characteristics of beach strawberry Fragaria chiloensis (L.) Duchesne affects population parameters of the twospotted spider mite Tetranychus urticae Koch. The results from this study show that clones of F. chiloensis and the cultivar "Totem" vary in suitability for the twospotted spider mite. Selected clones of F. chiloensis and the cultivar "Totem" differed also in the following foliar characteristics: densities of glandular and nonglandular trichomes and concentrations of total and catechol-based phenolics. In contrast, qualitative analysis of phenolic compounds, determined via HPLC, revealed a close similarity between F. chiloensis and F. x ananassa (cultivated strawberry) and among selected clones of F. chiloensis. Mite oviposition was negatively correlated with densities of glandular and nonglandular trichomes and concentrations of total foliar phenolics. In spite of these significant relationships, mite oviposition was best predicted by a combination of interacting plant characteristics rather than by any individual characteristic. Entrapment by sticky exudates from glandular trichomes appears to explain the negative relationship between mite survival and density of glandular trichomes. Spider mite development was negatively related to concentrations of foliar phenolics; twospotted spider mite development is delayed on leaves with high concentrations of phenolics. The correlation between mite development and foliar phenolics was greater when catechol-based phenolics were used. / Land and Food Systems, Faculty of / Graduate

Spiders and scorpions are efficient predators arachnid (PA) consuming preys larger than themselves. Few studies reported, molecularly, the digestion in PA. This work describes a biochemical, transcriptomic and proteomic analysis of the midgut and midgut glands (MMG) and digestive juice (DJ) from Nephilengys cruentata and Tityus serrulatus MMG. Cathepsin L, B, D and F, legumain, trypsin, astacin, carbohydrases and lipases were identified by these approaches. Peptide isomerase and ctenitoxins, which are venom proteins were identified, showing a correlation among digestive and venom enzymes. Summarily, PA relies in multi peptidase system mainly constituted of astacins for extracellular prey liquefaction and cathepsin L for intracellular digestion, describing a molecular model for digestion. Probably, during evolution, gene duplication led a diversification of astacins in the derived groups of Arachnida, like spiders, distinctly from what is observed in basal groups like scorpions. These data on Arachnida digestion will allow detailed multi disciplinary studies. / Aranhas e escorpiões são aracnídeos predadores eficientes (AP) consumindo presas maiores que eles mesmos. Poucos estudos descrevem molecularmente a digestão em AP. Neste trabalho caracterizamos bioquimicamente, por transcriptoma e proteoma o intestino e glândulas digestivas (IGD) e suco digestivo (SD) de Nephilengys cruentata e o IGD de Tityus serrulatus. Catepsinas L, B, D e F, legumaína, tripsinas, astacinas, carboidrases e lipases foram identificadas. Peptídeo isomerase e ctenitoxina foram identificadas no IGD. Estas proteínas podem indicar uma correlação entre enzimas digestivas e do veneno. Portanto, AP apresentam várias peptidases principalmente astacinas para liquefazer a presa extraoralmente e catepsinas L para digestão intracelular, descrevendo um modelo molecular para a digestão. Provavelmente, durante a evolução, eventos duplicação gênica levaram à diversificação das astacinas aracnídeos derivados, como as aranhas, diferentemente dos grupos basais, como os escorpiões. Estes dados sobre a digestão em Arachnida permitirão estudos multidisciplinares.

Studies on taste perception in nonhuman primates contribute to the understanding of the evolution of the sense of taste. To assess the responsiveness of four adult spider monkeys (Ateles geoffroyi) to a set of substances perceived as sweet by humans, two-bottle preference tests were performed to determine taste preference thresholds, and taste-induced facial responses were analyzed. The spider monkeys displayed a significant preference for concentrations as low as 0.2-1 mM acesulfame K, 0.002-0.5 mM alitame, 10-20 mM isomalt, 0.002-0.5 mM sodium saccharin, 2-20 mM galactose and 20-50 mM sorbitol over water. The spider monkeys were generally unable to perceive aspartame and, based on their facial responses, probably do not perceive it as sweet. Thaumatin and monellin were not detected, and most likely neither was the sweetness of sodium cyclamate. Sodium saccharine and sodium cyclamate were rejected at high concentrations by at least one monkey, which is congruent with the perception of a bitter side taste as reported in humans. A significant correlation was found between the ranking order of sweetening potency for the different substances of spider monkeys and humans, but not between spider monkeys and chimpanzees. The results suggest that spider monkeys may be generally more sensitive than chimpanzees and at least as sensitive as humans to the tested substances, supporting the notion that high sensitivity to sweet taste may be associated with a frugivorous dietary specialization. The lack of responsiveness to some of the substances supports the notion of a dichotomy in sweet-taste perception between platyrrhine and catarrhine primates.

Orientador: William Ricardo Amancio Santana / Resumo: O gênero anfi-americano Macrocoeloma Miers, 1879 é composto por caranguejos decoradores de habitats tropicais e subtropicais. Esses caranguejos são encontrados em substratos distintos, incluindo principalmente recifes de corais e rochas. Esse gênero passou por várias alterações sistemáticas em seu status de família, desde sua descrição original até a sua recente exclusão de Mithracidae. No início deste estudo Macrocoeloma era considerado incertae sedis, devido ao pouco conhecimento das relações entre as espécies do gênero e outros gêneros relacionados, sendo sua revisão taxonômica sugerida diversas vezes na literatura. Assim, com o objetivo de suprir essas lacunas taxonômicas e filogenéticas, este estudo empregou abordagens morfológicas e moleculares para reconstruir as relações filogenéticas de Macrocoeloma. Para isso, utilizamos um conjunto de dados moleculares combinados de um gene nuclear (18S) e três mitocondriais (12S, 16S, COI), usando máxima verossimilhança e inferência bayesiana. Além disso, uma inferência de delimitação de espécies foi realizada com o modelo de Poisson tree processes (PTP), usando a filogenia de máxima verossimilhança do gene mitocondrial COI. Foi realizada a revisão taxonômica de Macrocoeloma, com diagnóstico elaborado, descrições detalhadas e mapas de distribuição geográfica com base no material examinado. A monofilia de Macrocoeloma foi demonstrada, após exclusão de Pericera heptacantha Bell, 1836 e P. septemspinosa Stimpson, 1871. O gênero monot... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The amphi-American genus, Macrocoeloma Miers, 1879, is composed of decorator crabs from tropical and subtropical regions. These crabs are found on distinct substrates, including mainly coral reefs and rock. Macrocoeloma has undergone several systematic changes in its family status, since the original description until its recent exclusion of Mithracidae. Prior to this study, Macrocoeloma was considered incertae sedis, due to little knowledge of the relationships between species of the genus and related genera, and its taxonomic revision has been suggested several times in the literature. Thus, in order to address these taxonomic and phylogenetics gaps, this study employed morphological and molecular approaches to reconstruct the phylogenetic relationships of Macrocoeloma. We used a combined molecular dataset of a nuclear (18S) and three mitochondrial genes (12S, 16S, COI) using Maximum Likelihood and Bayesian Inference. In addition, the inference of species delimitation was performed with the Poisson tree processes model (PTP), using Maximum Likelihood phylogeny of the mitochondrial COI gene. The taxonomic revision of Macrocoeloma was provided with elaborated diagnosis, detailed descriptions and maps of geographic distribution based on examined material. The monophyly of Macrocoeloma was demonstrated after exclusion of Pericera heptacantha and P. septemspinosa. The monotypic genus Thersandrus Rathbun, 1897 is a sister group of Macrocoeloma, followed by the new genus proposed ... (Complete abstract click electronic access below) / Doutor

The aim of this thesis is to attempt to solve technical and spatial issues in an architectural project by looking at a species of spider, Cyrtphora Citricola. This will be done using desk-based research, reference reading and testing models. The work of architect Frei Otto will also be used as a reference for technical and programmatic solutions in the architectural intervention. The thesis will attempt to answer the question, ‘What aspects of technical and spatial adaptability can be brought into an architectural context by studying spiders and their behavior?’ Spider silk is built up through a protein chain hierarchy, making for a unique structural material. As a species, spiders are particularly adaptable to different living conditions. The specific species Cyrtphora Citricola has a very unique way of building its web which has a tent-shaped formation. It is very adaptable to different sites and living conditions and shares similarities with the tent and netted roof structures designed by Otto. Being a pioneer in the fields of minimal architecture and tension construction, he claims architecture needs to integrate with nature as well as be light and minimal in order to solve the environmental problems we face in modern society. These theories have influenced this thesis and the resulting architectural project proposal. To gain further understanding of tensional structures, experiments using two different methods of model making have been explored. The first uses string and soap film to test the naturally occurring minimal surface of physical models and the second uses a similar method by programming computational software to act like the soap film. The project is summarized in one potential usage of the spider in architecture, an elementary school located in the planned neighborhood Tomtebo Strand, Umeå. The plot is currently all forest, which will be used in the project as a statement of adaptability. As a result of insufficient research surrounding spiders, the project developed into a modern recreation of Otto’s work with tensile construction. The purpose of the architectural project ‘NETWORK’ is to investigate how a large structure can adapt to any location, causing minimal impact. By studying spiders and spider technology and combining the research with the work of Otto; aspects of adaptability, technical function and aesthetical form have been combined to create a project which answers the thesis question.

Cognition allows animals to acquire, process, and store sensory information from the environment and use it to adapt to their surroundings. A battery of behavioral tests was used to assess the cognitive abilities of black-handed spider monkeys (Ateles geoffroyi). Black and white cups were used to assess (1) object permanence by showing the animals under which cup the reward was placed, (2) associative learning by concealing where the reward was placed, and (3) long-term memory by repeating the second task after a 4-month break; petri dishes with varying amounts of food were used to assess (4) relative quantity discrimination; and boxes fitted with dotted cards were used to assess discrete number discrimination with (5) equallysized dots and (6) various-sized dots. For each task, one session comprised 10 trials (i.e. responses). All nine animals succeeded in all tests and, as a group, reached the learning criterion of 70% correct responses on session two in the object permanence and associative learning tasks; on session eleven in the quantity discrimination task; on session sixteen in the numerosity task with equally-sized dots; on session three in the numerosity task with various-sized dots; and averaged 84.4% correct responses in the long-term memory task. Their prompt high score in the numerosity task with various-sized dots suggests that the animals acknowledged the task for its numerical properties as opposed to the size or pattern of the dots. These cognitive abilities are thought to shape the necessary behaviors for the ecological and social needs of the species.

Circadian clocks enable coordination of essential biological and metabolic processes in relation to the 24-hour light cycle. However, there are many habitats that are not subject to this light cycle, such as the deep sea, arctic regions, and cave systems. This study analyzes the circadian pattern of isolated populations of a subterranean spider, Meta ovalis from two Tennessee caves and five Indiana caves. Locomotor activity was recorded with TriKinetics LAM50 Locomotor Activity Monitor under a 12-hour light (L), 12-hour dark (D) (LD 12:12) cycle preceding total darkness (DD). Significant differences were found within and among populations found in Tennessee cave systems in average free running period and onset of locomotor activity. Selection, drift, and genetic fixation are explored as the causes of variation in the present study, using M. ovalis as the model organism. All five caves in Indiana show little variation, whereas both Tennessee caves show large interindividual variation.

Ecologically, spiders are both predators and prey. Therefore, they must balance being aggressive enough to forage successfully, but not so aggressive that they become overly exposed to predation. Some species of spiders actively forage during clearly defined periods of the day, leading to the hypothesis that they should be less aggressive (or more defensive) during periods when they are not foraging, predicting that antipredator behaviour should be more pronounced during inactive foraging times. We tested the antipredator 'huddle response' in a nocturnal foraging orb-weaver, Larinioides cornutus, and found that, as predicted, the spiders huddled longer in the day than at night. We then conducted tests to determine whether the cycling of the response was regulated by an internal clock (circadian), and we found that huddle duration continued to cycle under constant dark (with periodicity significantly less than 24. h) as well as under constant light (periodicity nonsignificantly longer than 24. h). This work adds a novel behaviour to the list of behaviours under circadian control and also to the surprisingly short list of studies demonstrating circadian rhythm in spiders.

Correlated individual differences in behaviour across ecological contexts, or behavioural syndromes, can theoretically constrain individuals' ability to optimally adjust their behaviour for specific contexts.Female Anelosimus studiosus exhibit a unique behavioural polymorphism: 'social' females are tolerant of conspecifics and aggregate in multi-female colonies, while 'solitary' females aggressively defend their singleton webs from intrusion by adult female conspecifics. Previous work found that social females are also less aggressive toward prey and are more fearful of predators.In this study we quantify potential fitness consequences of these correlated behaviours by examining the potential and realised fecundities of the two phenotypes in naturally occurring colonies, and by quantifying their ability to rear offspring as singleton individuals.There were no differences in the fecundities of laboratory-reared females between the phenotypes, nor were there differences in field-collected brooding females from naturally occurring solitary and social nests.Brooding females from solitary and social colonies that were isolated in new nests for the growing season were both capable of rearing their broods; however, females from solitary nests had significantly greater success.These results suggest a fitness consequence to the reduced-aggression syndrome of social females that may represent a general impediment to the evolution of sociality in spiders.