Dissertations / Theses on the topic 'Myriapode'

La terrestrialisation (colonisation des milieux terrestres) est une étape majeure de l'histoire de la vie. Elle s’accompagne d’une explosion de la diversité biologique en milieu continental (terre ferme, milieu aérien), et remodèle les enveloppes superficielles de la Terre. Dans le règne animal, les arthropodes apparaissent comme les principaux acteurs de cette révolution écologique (ex : insectes, arachnides) qui débute probablement dès l’Ordovicien (485-444 Ma) et s’accentue au Carbonifère (359-299 Ma). Une autre composante majeure de cette faune arthropodienne, les myriapodes (‘milles pattes’), semble avoir colonisé les milieux terrestres très tôt et joué un rôle crucial dans le développement initial des sols et le cycle des nutriments, ouvrant ainsi la voie à de nouvelles colonisations végétales et animales. Le gisement à préservation exceptionnelle de Montceau-les-Mines (Saône-et-Loire ; Carbonifère, ~305 Ma) possède une flore et une faune riches et diversifiées conservées en 3D dans des nodules et offre donc une véritable fenêtre évolutive sur la terrestrialisation. Le but de cette thèse est d'étudier les trois groupes de myriapodes présent à Montceau-les-Mines: les diplopodes ("millipedes" en anglais), les arthropleurides et les euthycarcinoïdes afin de reconstituer avec précision leur morphologie, leur mode de vie, leurs adaptations à la vie continentale, leur rôle dans l’écosystème continental ainsi que leurs relations phylogénétiques (avec leurs représentants actuels)
Terrestrialisation (colonisation of terrestrial environments) is a major step in the history of life. It goes along an explosion of biological diversity in continental environment (land and aerial environment), and reshape the superficial envelopes of Earth. In the animal kingdom, arthropods are one of the main actors of this ecological revolution (ex : insects, arachnids) that begins surely since the Ordovician (485-444 Ma) and increases during the Carboniferous (359-299 Ma). Another main part of this arthropod fauna, the myriapods (millipedes and centipedes), seems to colonise land early and play a crucial role in initial development of soils and nutriments cycle, leading the way to new floral and faunal colonisations. The exceptionnally preserved locality of Montceau-les-Mines (Saône-et-Loire; Carboniferous ~ 305 Ma) yields a rich and diversified flora and fauna preserved in 3D in nodules and offer an evolutive window on terrestriaisation. This PhD goal is to study the three groups of myriapods present in Montceau-les-Mines: the diplopods ("millipedes"), the arthropleurids and the euthycarcinoids to reconstruct with accuracy their morphology, their life mode, their adaptations to continental life, their role in continental ecosystem as well as their phylogenetic relationships (with extant representatives)

Dans le cadre du programme de recherches concertees environnement et activites humaines - etude d'un secteur pollue par les metaux mis en uvre par le conseil regional du nord-pas de calais, l'etude de l'etat de la faune invertebree du sol d'une zone polluee par les metaux a ete entreprise. Le suivi annuel de la diversite faunistique de cinq stations presentant des degres divers de pollution ainsi que celui de deux stations temoins a ete realise. Il n'a pas ete mis evidence de distorsion flagrante de la qualite des peuplements dans les zones moyennement polluees. Inversement, la faune de la pelouse metallicole d'auby presente un important deficit en invertebres decomposeurs a mettre en relation avec l'accumulation de litiere observee. Dans un deuxieme temps et dans un souci de developpement d'outil de diagnostic des zones contaminees, l'etude de la physiologie et du stress metallique chez deux modeles biologiques eisenia fetida (annelide, oligochete) et lithobius forficatus (myriapode, chilopode) a ete entreprise. Les dynamiques d'accumulation des metaux ont mis en evidence des strategies opposees de detoxication : eisenia fetida stocke de maniere cumulative le cadmium et le plomb alors que lithobius forficatus apres une breve periode d'accumulation du metal ingere, l'excrete de maniere efficace. Aucun effet des metaux sur differentes cibles enzymatiques, biomarqueurs potentiels n'a ete mis en evidence. La localisation tissulaire des metaux chez les deux modeles a ete tentee par voie d'autometallographie.

Nous avons examine en languedoc les variations saisonnieres de la structure des peuplements des diplopodes en fonction des perturbations anthropiques, estime leur role de consommateurs de litiere, et teste en laboratoire l'influence de certains facteurs pouvant affecter leur microdistribution ou leur rythme d'activite. Les milieux les plus favorables sont constitues par les taillis, ou les diplopodes forment les peuplements dominants des organismes consommateurs de litiere. Leur role est determinant dans la fragmentation de la litiere, participant a sa transformation en synergie avec les microorganismes edaphiques. La photoperiode, la temperature, l'humidite de la litiere et du substrat, la nature de celui-ci, sont parmi les principaux facteurs qui controlent le taux de consommation de la litiere qui est maximal au printemps et en automne, le froid hivernal et la secheresse estivale ralentissant le processus. La litiere agee est plus consommee que celle de l'annee. L'origine geographique des individus peut modifier les preferences alimentaires. Sous taillis de chene vert les diplopodes fragmentent entre 11 et 15% au moins de la litiere tombee au sol annuellement. De nombreux facteurs anthropiques (coupes a blanc, eclaircies, paturage, pietinement) sont susceptibles de modifier l'organisation des peuplements de diplopodes, entrainant des changements dans le taux de fragmentation de la litiere. Les glomerida sont plus sensibles que les iulida a ces perturbations
The seasonal variation of diplopod community structure has been examined in languedoc, according to anthropic perturbations. The role of the diplopods as litter consumers has been estimated and the influence of specific factors which affect their microdistribution or their activity rythm has been tested in the laboratory. The most favourable environments are constituted by the coppice where the diplopods compose the dominant community among litter consumers. Diplopods have an essential role in the litter fragmentation. They take part in its transformation, synergistically with edaphic microorganisms. Photoperiod, temperature, water content of both leaves and substrate, as well as soil nature, are important factors which control litter consuming rate. This is maximal during spring and autumn because winter frost and summer drought slow down the consuming process. Old litter is more consumed than the current-year litter. The geographic origin of the millipedes can modify feeding preferences. It has been shown that under holm-oak coppice, diplopods fragment at least from 11% to 15% of the litter which falls down annually on the ground. Many anthropic factors (cutting, clearing up, animal feeding, trampling,. . . ) are able to modify the community organization of the diplopods, leading to change in the fragmentation rate of the litter. The glomerida are more sensitive than the iulida to those perturbations

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Os artrópodos constituem um grupo que possui um extenso registro fossilífero e hoje constitui o grupo mais abundante e diverso dos animais terrestres. Suas pistas fossilizadas, aliadas a estudos geológicos, fornecem dados importantes para estudos paleoecológicos. Através da análise da oscilação da densidade de icnofósseis ao longo dos horizontes do Parque do Varvito (Município de Itu – SP) foram realizadas inferências sobre a história geológica da área, sobre a população de artrópodos que provavelmente ali viveu e sobre as condições ambientais que a circundava. Para isso foram utilizadas metodologias como a do esquadrinhamento para obter informações a respeito da densidade e direcionamento das pistas e experimentos com a finalidade de reproduzir as pistas em condições semelhantes aquelas encontrados no parque. Além disso, foi realizada uma classificação icnotaxonômica das pistas e sua atribuição a diplópodos (Myriapoda) terrestres. A contextualização da análise tafonômica com a história deposicional do Parque do Varvito levou a conclusão de que os miriápodos, de hábitos terrestres, habitavam uma área de inundações cíclicas e, conseqüentemente, passavam por condições de estresse ambiental no verão, quando a área recebia o afluxo da água de degelo de uma geleira localizada a uma distância relativamente grande da região do Parque durante o Carbonífero. A condição de estresse ambiental para esta fauna, que poderia ou não causar episódios de mortalidade, ocorria em função de uma fina lâmina d’água que provinha da geleira. Pelo fato das pistas estarem com direcionamento preferencial, pode-se inferir que esses animais fugiam das inundações durante o verão (condição estressante), cujo fluxo de água teria provavelmente uma orientação similar. Considerando as evidências da influência periglacial e o aporte da água de degelo, o frio intenso poderia ter levado ao congelamento dos solos no ambiente terrestre, gerando ambientes subaquáticos rasos, bem como a formação de capas de gelo, o que dificultaria as trocas gasosas e a obtenção de nutrientes. As pistas também apresentam formas circulares e semicirculares que foram interpretadas como marcas de agonia do animal sob situação de estresse, corroborando a reconstrução paleoecológica inferida no presente estudo.
The arthropods represent the most extensive fossil register and the most abundant and diverse group of all terrestrial animals. Their track and trails provide important data for the study of this group evolution besides helping understanding their diversity and modern distribution. By analyzing the oscillation of the density of ichnofossils along the horizons of Varvito´s Park (Itu – SP), were made inferences about the geological history of the area, the population of arthropods that probably lived there and on the environmental conditions that surrounded them. For the analysis of the density and direction of the tracks, the methodology used was the esquadrinhamento. Also, an experiment was conducted in order to replicate the tracks in similar conditions to those found in the Park during the Carboniferous. It was made a taxonomic classification of the tracks and they were assigned to terrestrial diplopods (Myriapoda). The contextualization of the taphonomic analysis and the depositional history of Varvito´s Park led to the conclusion that myriapods, which have terrestrial habits, inhabited an area of cyclic flooding and therefore experienced environmental stress conditions in the summer, when the area received an influx of meltwater from a glacier located at a relatively long distance of the Park during the Carboniferous. The condition of environmental stress for this fauna, which may or may not cause episodes of mortality, was taking place due to the a thin sheet of water that came from the glacier. Because the tracks were in a preferred direction, one can infer that these animals got away from floods during the summer (stressful condition), which flow of water would probably have a reverse orientation. Considering the evidences of periglacial influence and the outflow of meltwater, the cold might have led to the freezing of soils in the terrestrial environment, creating shallow underwater environments, as well as the formation of ice sheets, thereby impeding gas exchange and the obtainment of nutrients. The tracks also present circular and semi-circular forms and have been interpreted as marks of animals’ agony under stressed conditions, corroborating the paleoecological reconstruction inferred.

Rhinocricus Karsch, 1881 possui atualmente 207 espécies descritas e distribuídas principalmente pelo continente americano, das quais 65 são descritas para o Brasil. A descrição do gênero foi baseada na presença de escobinas (depressões na porção distal dos prozonitos). O presente estudo avaliou a monofilia de três grupos de espécies previamente propostos em Rhinocricus. A matriz de dados foi composta por 39 caracteres morfológicos e 30 espécies terminais, sendo 21 como grupo interno e nove do grupo externo. Nós realizamos uma analise de parcimônia com pesos implicitos usando o software TNT e obtivemos a melhor árvore com a mesma topologia para três melhores valores de K (5.992, 7.309, 9.105). Nenhum dos três grupos de espécies de Rhinocricus foi recuperado monofilético. Rhinocricus (Erythocricus) sanguineostriatus foi recuperado irmão de todas as outras espécies, e Argentocricus Verhoeff, 1941 resultou parafilético. Os caracteres diagnósticos tradicionalmente utilizados para separar grupos de espécies, subgênero e gênero não foram recuperados como sinapomorfias. Ainda durante o exame do material quatro novas espécies de Rhinocricus foram descobertas e são aqui descritas. Futuras investigações incluindo amostras mais amplas de espécies são necessárias, para estabelecer hipóteses de relacionamento robustas entre R. (Erythocricus), Argentocricus, e o restante das espécies de Rhinocricus, deste modo identificando grupos monofiléticos no gênero e suas sinapomorfias.
Rhinocricus Karsch, 1881 currently has 207 species described and distributed mainly by the American continent, of which 65 are described for Brazil. The genus was based on the presence of scobinae (depressions in distal portion of prozonit). The present study evaluated the monophyly of three groups of species previously proposed in Rhinocricus. The data matrix was composed for 39 morphological characters and 30 species as terminal taxa, being 21 the ingroup, and nine the outgroup. We performed a parsimony analysis with implied weights using TNT software, obtaining the same best topology with three optimal K-values (5.992, 7.309, 9.105). None of the three previously proposed species groups of Rhinocricus was recovered monophyletic. Rhinocricus (Erythocricus) was recovered sister to all other species, and Argentocricus Verhoeff, 1941 resulted paraphyletic. The diagnostic characters traditionally used to separate species groups, subgenera, and genera were not recovered as synapomorphies. Still during the examination of the material four new species of Rhinocricus were discovered and here described. Further investigation including a broader species sample is needed attempting to establish robust relationship hypotheses between R. (Erythocricus), Argentocricus, and the remainder species of Rhinocricus, thus identifying the monophyletic groups in the genus and their synapomorphies.

The monophyletic taxon Diplopoda, which is classified as a class, is one o f the four taxa within the monophyletic subphylum Myriapoda that plays an important role in terrestrial ecosystems. Millipedes represent important members o f soil macrofauna due to their role in the soil forming processes that are connected with the biodégradation and fragmentation of dead plant material and other organic matter. As the material for study, two millipede species: Archispirostreptus gigas and Julus scandinavius have been selected. A. gigas commonly called as the giant millipede, is one o f the largest known millipedes and is widespread in the south-eastern regions of Africa. J. scandinavius is distributed mainly in Central and Northern Europe with a marginal extension into the Balkan and East European regions, so it is a representative o f our native fauna. Millipedes are an object of many toxicological and ecophysiological studies, however, knowledge about the ultrastructure and physiology o f the digestive system of these animals is still incomplete. The research was carried out to obtain information on the details o f the ultrastructure o f midgut epithelium and to describe the physiological processes which take place in the midgut of above-mentioned species. The material was analyzed using light, fluorescence and transmission electron microscopies. The results o f this study have shown that in both millipedes examined here, the midgut has the tube-shaped internal duct that spreads along the entire length of the middle region of the body. It is surrounded by visceral muscles and hepatic cells (liver cells) distributed along its length. Hepatic cells form the fusiform junctions that protrude into the basal regions of the midgut epithelium. These cells play an important role in the storage and transport o f backup materials and are responsible for the accumulation and neutralization o f harmful substances that originate from the metabolism or food. The midgut is lined with a pseudostratified columnar epithelium in which all cells come into contact with the basal lamina. The midgut epithelium is lined with coated multi-layer perytrophic membrane with a regular grid pattern. Three types o f cells can be distinguished among the epithelial cells: digestive cells, secretory cells and regenerative cells. The most numerous cells are digestive cells which have a columnar shape and a distinct regionalization in organelles distribution as has been described for other arthropods. The basic role o f these cells is the digestion and absorption as well as the transport and accumulation. They are responsible for the synthesis and secretion. Substances that are produced and accumulated in the cytoplasm o f the digestive cells are released into the midgut lumen due to microapocrine secretion in both species, while the apocrine secretion was observed, only in J. scandinavius. Histochemical stainings showed that lipids, polysaccharides and glycolipids accumulated in both o f the species that were analyzed. However, proteins were detected only in J. scandinavius. The second type of cells in midgut epithelium are regenerative cells, which are individually distributed along the entire length o f the midgut in the basal regions of digestive cells. The mitotic divisions o f the regenerative cells in J. scandinavius and A. gigas result in the formation of two cells. One o f them is the regenerative cell as it is, and another differentiates into the digestive cell. Thus, the divisions of regenerative cells are asymmetric. Regenerative cells in both species could play the role o f unipotent midgut stem cells. Secretory cells are also individually dispersed among the basal regions o f the digestive cells. They do not contact the midgut lumen, and therefore they are o f a closed type. Their ultrastructure is similar with ultrastructure of endocrine cells in insects. They are characterized by the presence of numerous granules o f different electron density in the entire cytoplasm. In J. scandinavius, all secretory cells have the same structure, whereas in A. gigas two types of these cells have been distinguished. The processes o f degeneration o f the central epithelium occur through autophagy, apoptosis and necrosis. These types o f cell death are typical, also described in other invertebrates. In both the species examined here, the autophagy could be induced by changes in the ultrastructure and function o f cell organelles and the presence o f potentially toxic substances. It is the kind o f strategy o f cell survival. Apoptosis is the most common type o f cell death in the midgut epithelium o f J. scandinavius. It is a major process o f removing disrupted and damaged cells from the epithelium and it participates in homeostatic maintenance. In A. gigas mainly necrosis is responsible for described function, while the apoptosis is less frequent.

De precedentes etudes avaient montre que le venin du diplopode glomeris marginata contient deux alcaloides originaux: la glomerine et l'homoglomerine. Nous avons identifie ces alcaloides dans le venin de deux autres especes: g. Annulata et g. Guttata, ainsi qu'un nouveau derive de la quinazolinone, la 6-methoxy-glomerine, dont la structure a ete etablie sur la base de diverses donnees spectrales (uv, rmn-1h, ms). Ces alcaloides sont faiblement toxiques a l'egard des insectes et seules la glomerine et l'homoglomerine ont montre une toxicite significative a l'egard des vertebres (dl50 9. 7 et 6. 4 mg/kg en injection intraperitoneale chez la souris). Les 2,5-dialkylpyrrolidines presentes dans le venin des fourmis du genre monomorium sont des insecticides naturels provoquant une paralysie flasque. Nous avons determine le mecanisme d'action de la 2-(1non-8enyl)-5-(1non-8enyl)pyrrolidine (pyr 9) sur le systeme nerveux d'invertebre, en utilisant deux types de preparations in vitro de la chaine nerveuse ventrale de l'ecrevisse procambarus clarkii). Nos resultats montrent clairement que la pyr 9 bloque la conduction nerveuse sans affecter le potentiel de repos. Des experiences de potentiel impose sur axone ont demontre que ce blocage est du a une inhibition du courant sodium, qui s'accompagne d'un deplacement de la courbe d'inactivation du courant sodium vers les potentiels plus negatifs