Éditeur(s) : HAL CCSD
Résumé : Ctenophores are one of the four animal phyla positioned outside from the Bilateria. Most ctenophore species are planktonic and gelatinous, and are easily recognisable by their eight comb rows used for swimming. Ctenophore systematics remains nowadays poorly understood. Anatomical characters do not help much in placing them within the animal tree, and similarly the grounds for establishment of their internal phylogeny as well as delimitation of species are notoriously weak due to a paucity of informative morpho-anatomical characters. Until now, the use of molecular data has failed to improve significantly this situation. The aim of this PhD thesis was to bring a contribution to our understanding of ctenophore evolution at different taxonomic scales. At the metazoan level, the position of ctenophores was addressed using a phylogenomic approach. Taxonomic sampling was significantly improved through sequencing and assembly of transcriptomes of 22 non-bilaterian species (belonging to ctenophores, cnidarians and sponges). Two independent datasets were analysed, one consisting in an update of an existing supermatrix of 128 genes, the other one (4235 genes) having been entirely built de novo, thanks to a newly-devised semi-automated protocol intended to eliminate all major potential causes of artefacts (contaminations, paralogies, missing data). Results clearly contradict recent phylogenomic studies which claimed Ctenophora to be the most early-diverging animal lineage, our analyses instead supporting Porifera as the sister-group to other metazoans. The exact position of ctenophores remains however uncertain at this stage, different conditions of analyses yielding three contradictory hypotheses as open possibilities. At the intra-phyletic level, analyses of a ADNr 18S and ITS (internal transcribed spacers) dataset, together with study of duplicated genes and the results of phylogenomic analyses, allowed resolving most phylogenetic relationships between ctenophore orders and families, including the placement of the ctenophore tree root. Finally, at smaller taxonomic scale, in-depth comparison between two species of the genus Pleurobrachia using immunohistochemistry demonstrates the potential of these techniques for uncovering new structural “micro-anatomical” characters useful for diagnosis and identification of ctenophore species. It is our hope that this work will contribute to improving the systematics of a poorly known phylum of great importance for understanding early animal evolution.
Les cténophores représentent l’un des quatre embranchements animaux extérieurs aux Bilateria. La majoritédes espèces sont planctoniques et gélatineuses, et sont reconnaissables à leurs huit rangées de peignes dont lebattement permet la nage. Leur systématique est encore de nos jours mal comprise. L'anatomie descténophores offre peu de caractères aussi bien pour placer la lignée dans l’arbre des métazoaires, que pourétablir les relations de parenté au sein de l’embranchement et délimiter les espèces, et jusqu’à présent lesdonnées moléculaires n’ont pas permis de résoudre ces problèmes de manière satisfaisante. L’objectif de cetravail de thèse est de contribuer à améliorer notre compréhension de l'évolution des cténophores àdifférentes échelles taxonomiques. A l’échelle des métazoaires, la position phylogénétique des cténophores aété abordée par une approche phylogénomique. Un effort significatif a été réalisé pour améliorerl’échantillonnage taxonomique à travers le séquençage et l’assemblage des transcriptomes de 22 espèces denon-Bilateria (cténophores, cnidaires, spongiaires). Deux jeux de données indépendants ont été analysés, lepremier représentant une mise à jour d’une supermatrice existante de 128 gènes ; le second (4235 gènes)ayant été entièrement construit de novo via un protocole original comportant la mise au point de nouvellesméthodes pour traiter de manière semi-automatisée les principales sources potentielles d’artéfact(contaminations, paralogies, données manquantes). Les résultats contredisent certaines études récentes enmontrant que les spongiaires et non les cténophores représentent le groupe-frère des autres métazoaires. Laposition exacte de ces derniers reste à ce stade incertaine (trois options se présentant suivant les analyses). Al’échelle intra-phylétique, l'analyse d'un jeu de données comprenant les marqueurs ADNr 18S et InternalTranscribed Spacers (ITS), associée à des analyses de gènes dupliqués chez les cténophores et aux analysesphylogénomiques précédentes, a permis de résoudre une grande partie des relations phylogénétiques entre lesordres et les familles de cténophores, tout en permettant de préciser la position de la racine. Enfin, à uneéchelle taxonomique plus fine, une comparaison approfondie entre deux espèces du genre Pleurobrachia aumoyen de marquages immunohistochimiques montre le potentiel de ces techniques comme source denouveaux caractères structuraux « micro-anatomiques » à valeur diagnostique pour la délimitation etl’identification des espèces de cténophores. En conclusion, ce travail se veut une contribution au progrès dela systématique d’un embranchement encore méconnu et d’une grande importance pour la compréhensiondes évènements anciens de l’évolution animale.
https://tel.archives-ouvertes.fr/tel-01165014

NNT : 2014PA066448
tel-01165014
https://tel.archives-ouvertes.fr/tel-01165014
https://tel.archives-ouvertes.fr/tel-01165014/document
https://tel.archives-ouvertes.fr/tel-01165014/file/these_archivage_3158995o.pdf

Éditeur(s) : Rome : Vitale Mascardi
Résumé : "Les 5 premières parties (vol. 1 et vol. 2) ont une pagination continue. Le traité de Hernandez, à la fin du volume 2, a seul une pagination spéciale. Titre en rouge et noir, avec vignette gravée sur cuivre. Nombreuses figures sur bois dans le texte de plantes, animaux et minéraux. - Reliure veau brun, dos à 6 nerfs, 17e siècle. - Cachet de la bibliothèque de la Ville de Bordeaux. Leclerc, 1154. - Palaü y Dulcet, 113 538. - Pritzel, 4000. - Sabin, 31516"
Siècle(s) traité(s) : 17
Droits : Domaine public
Provenance : Ville de Bordeaux. Bibliothèque municipale
Permalien : http://www.manioc.org/patrimon/BBX17012
BBX17012

Éditeur(s) : HAL CCSD Wiley
Résumé :  
Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential-power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change.
ISSN: 1354-1013

hal-01032162
https://hal.archives-ouvertes.fr/hal-01032162
DOI : 10.1111/j.1365-2486.2009.01891.x

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Disentangling the autotrophic and heterotrophic components of soil CO2 efflux is critical to understanding the role of soil system in terrestrial carbon (C) cycling. In this study, we combined a stable C-isotope natural abundance approach with the trenched plot method to determine if root exclusion significantly affected the isotopic composition (δ13C) of soil CO2 efflux (RS). This study was performed in different forest ecosystems: a tropical rainforest and two temperate broadleaved forests, where trenched plots had previously been installed. At each site, RS and its δ13C (δ13CRs) tended to be lower in trenched plots than in control plots. Contrary to RS, δ13CRs differences were not significant. This observation is consistent with the small differences in δ13C measured on organic matter from root, litter and soil. The lack of an effect on δ13CRs by root exclusion could be from the small difference in δ13C between autotrophic and heterotrophic soil respirations, but further investigations are needed because of potential artefacts associated with the root exclusion technique.
ISSN: 0032-079X

bioemco-00353850
https://hal-bioemco.ccsd.cnrs.fr/bioemco-00353850
DOI : 10.1007/s11104-008-9844-5

Éditeur(s) : HAL CCSD
Résumé :  
The gelatinous layer (G-layer) of tension wood fibres in hardwood contributes to the mechanical function of the living tree and has significant consequences on properties of solid wood. Its size, shape and structure observed by optical or electron microscopy exhibits characteristic anatomical features. However, we found that sectioning of non-embedded wood samples results in an uncontrolled swelling of the G-layer was monitored by serial sections, from an embedded wood sample, from its trimmed transverse face to that located several hundreds of micrometers deep. The results revealed that the initial cutting before embedding produced a border effect responsible for the swollen nature, which is similar to sections from non-embedded material. After a conventional embedding technique was applied, a section of at least 30 micrometres below the trimming surface is required to observe an un-swollen G-layer.
IAWA Journal

hal-01032054
https://hal.archives-ouvertes.fr/hal-01032054

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Numerous archeomagnetic studies have provided high quality data for both the direction and the intensity of the geomagnetic field, essentially in Europe for the last 10 millennia. In particular, Greece supplies a lot of archeological materials due to its impressive cultural heritage and volcanic activity, so that numerous data have been obtained from burnt clays or historical lava flows. The most recent Greek secular variation curves are available for the last 8 millennia for the intensity and the last 6 millennia for the direction. Nevertheless, the coverage still presents several gaps for periods older than 2500 BC. In an effort to complete the Greek curve and extend it to older times, we present the archeointensity results from three Neolithic settlements in Northern Greece. The samples are of two different natures: burnt structures from Avgi (5250 ± 150 BC) and Vasili (4800 ± 200 BC), as well as ceramics from Dikili Tash (4830 ± 80 BC) and Vasili (4750 ± 250 BC). The samples have been subjected to standard rock magnetic analyses in order to estimate the thermal stability and the domain state of the magnetic carriers before archeointensity measurements. Surprisingly, very few ceramic samples provided reliable archeointensities whereas samples from burnt structures presented a very good success rate. Complementary studies showed that a detailed examination of the matrix color, following archeological information and classification standards can be a decisive test for pre-selection of sherds. In spite of these unsuccessful measurements from ceramics, we obtained an intensity value of 73.5 ± 1.1 μT for Dikili Tash, a higher value than the other data obtained in the same area, during the same period. However we do not have evidences for a technical artefact during the experiment. The burnt structures yielded two reliable archeointensities of 36.1 ± 1.8 μT and 46.6 ± 3.4 μT for Avgi and Vasili, respectively. Finally, we achieved a new archeomagnetic dating for these sites by comparing these new archeointensity values, combined to the directional measurements already published, with the Bulgarian secular variation curve. These new results contribute to extend the Greek secular variation reference curve towards older periods.
ISSN: 0031-9201

hal-00805575
https://hal.archives-ouvertes.fr/hal-00805575
DOI : 10.1016/j.pepi.2012.10.011

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The decay of 187Re to 187Os provides a unique tracer of recycled lithosphere in the Earth's upper mantle, and the radiogenic Os isotope compositions of many mid-ocean ridge basalts (MORB) have been taken to indicate the presence of recycled oceanic crust in the mantle source. However, others have attributed the data to contamination by seawater or an age effect (due to 187Re decay following igneous crystallisation). This study presents new Re Os, U Th Ra and B isotope data for normal-MORB (N-MORB) glass (including 18 samples analysed previously). The scale of the variation in 187Os/188Os observed here in N-MORB glass ranges from 0.126 to 0.148, with a mean value of 0.133 ± 0.009 (2?). Previously published Os isotope data for MORB is shown to have been affected by an analytical artefact, and in particular the very radiogenic Os isotope compositions reported earlier are now shown not to exist. Nevertheless, some radiogenic Os isotope compositions are still seen in the data obtained here. Coupled Th and Ra excesses appear to rule out an age effect, at least, for those samples studied, however, ?11B covariations with 187Os/188Os are consistent with the assimilation of older oceanic crust (affected by seawater contamination). Individual sulphides (less likely to be affected by such contamination) are always less radiogenic than their glass host, with 187Os/188Os values ranging from 0.123 to 0.131. This indicates that sulphide precipitation occurred prior to contamination of the surrounding melt, but the data also suggest that low-Os sulphides have been affected by contamination through partial equilibration with that melt. Taken together, these indicate that dominant process responsible for the radiogenic Os isotope compositions of N-MORB glass is contamination by older oceanic crust. Although the influence of age effects and the presence of recycled material cannot be completely ruled out, Os-rich sulphides yield sub-chondritic Os isotope compositions which point rather to a long-term depletion in Re in the MORB source likely to have resulted from formation of the continental crust over much of Earth's history.
ISSN: 0012-821X

hal-00320075
https://hal.archives-ouvertes.fr/hal-00320075
DOI : 10.1016/J.EPSL.2007.05.014

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0378-8741

hal-01082177
https://hal-agroparistech.archives-ouvertes.fr/hal-01082177
DOI : 10.1016/j.jep.2006.09.045

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : We use InSAR to measure deformation and kinematics of the Mw = 4.9 Borujerd (2005/05/03) and Mw = 6.1 Chalan-Chulan (2006/03/31) earthquakes that occurred in the Zagros fold-and-thrust belt. The focal mechanism of the 2006 event is consistent with right lateral strike-slip motion and the event ruptured the Dorud-Borujerd segment of the Main Recent Fault. An Envisat interferogram spanning the 2006 event shows peak ground deformation of 9 cm in the satellite line-of-sight along a 10 km long fault portion. The interferogram spanning the 2005 earthquake is rather related to atmospheric artefact than to ground deformation. Dislocation models of the 2006 Chalan-Chulan event indicate dextral slip amounting to a maximum of 90 cm at a depth of 4 km. The predicted vertical displacements are in good agreement with differential levelling data. The 2006 event filled only a small part of the seismic gap located between large M = 7 events that occurred in 1909 and 1957.
ISSN: 0954-4879

hal-00411313
https://hal.archives-ouvertes.fr/hal-00411313
DOI : 10.1111/j.1365-3121.2008.00797.x

Éditeur(s) : Wiley-blackwell Publishing, Inc
Résumé : Oceanic larvae of the European (Anguilla anguilla) and American (A. rostrata) eels have to cross the Atlantic Ocean from the Sargasso Sea to European or North American coasts before entering continental habitats. In some European rivers, eel recruitment is now < 1% of levels in the 1980s. A better understanding of the effects of anthropogenic pressures and environmental fluctuations on eel larvae and subsequent recruitment is a prerequisite to build efficient management plans. The present paper provides insight into the critical oceanic phase of the eel life cycle with a focus on the duration of the larval migration whose estimates varies between 7 months and more than 2 years in both species. Does this range correspond to a natural variability in larval duration or does it stem from methodological artefacts? We first review the different methods used to estimate the duration of larval migration and critically describe their possible sources of misinterpretation. We then evaluate the consistency of these methods with the current knowledge about the ecology and physiology of eel larvae and the physical oceanography. While a moderate discrepancy in migration duration was found between methods for the American eel, the discrepancy was large in the European eel. In this species, otolith microstructure studies indicated migration durations between 7 and 9 months, while other methods pointed to durations of about 2 years. We show that estimates in favour of a long migration duration seem more robust to methodological caveats than methods estimating short durations of migration.
Fish And Fisheries (1467-2960) (Wiley-blackwell Publishing, Inc), 2010-09 , Vol. 11 , N. 3 , P. 289-306

Droits : 2010 Blackwell Publishing Ltd.
http://archimer.ifremer.fr/doc/00011/12208/9033.pdf
DOI:10.1111/j.1467-2979.2010.00362.x
http://archimer.ifremer.fr/doc/00011/12208/

Éditeur(s) : Para : Typographia de Santos & Menor
Siècle(s) traité(s) : 18
Droits : Domaine public
Provenance : Collectivité territoriale de Guyane. Bibliothèque Alexandre-Franconie
Permalien : http://www.manioc.org/patrimon/FRA11187
FRA11187