Tesi sul tema "Radiolaires – Morphologie (biologie) – Évolution"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-37 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Radiolaires – Morphologie (biologie) – Évolution".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
Carlsson, Veronica. "Artificial intelligence in radiolarian fossil identification : taxonomic, biostratigraphic and evolutionary implications". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR092.
Micropaleontology is not only about studying the organisms themselves, rather understanding Earth's past environments, with applications ranging from biostratigraphy to paleoceanography as well as being able to study evolutionary changes within morphospecies in time and space. This field is facing numerous challenges, since the analysis of microfossils demands significant human effort and taxonomic expertise, often leading to inconsistencies in interpretations. This work focuses on the application of using Artificial Intelligence (AI), such as Artificial Neural Networks (ANNs), for automatic image recognition of tropical Atlantic middle Eocene radiolarians. Large datasets have been constructed, in order to train different neural networks and our results show that the neural networks can automatically classify several different classes of radiolarians down to a species level, as well as in many cases being able to identify closely related species and even evolutionary transition morphotypes. It has also been able to correctly identify less broken or blurry radiolarians. It was also successfully applied to automatic image recognition for a biostratigraphic work, which in general could detect more general ages or highly precise bio events. This work includes the use of the classical neural network approaches for analysing visual context such as Convolutional Neural Networks (CNNs) but also includes the use of Spiking Neural Networks (SNNs), which is not as commonly used for automatic image recognition, as CNNs. SNNs resulted in almost or equal amount of accuracy obtained as for CNNs, just that the use is more computational efficient and takes up less memory. There have also been some comparisons using traditional morphometric analyses, such as Linear Discrimination Analysis (LDA), giving approximately the same kind of results. Our research not only aims to simplify and speed up the analysis process but also helps in increasing the accuracy and consistency of micropaleontological interpretations, which eventually, will contribute to the high-resolution studies in order to understand Earth's past history
Dutel, Hugo. "Histoire évolutive, morphologie fonctionnelle et développement des cœlacanthes mésozoïques et actuels". Paris, Muséum national d'histoire naturelle, 2013. http://www.theses.fr/2013MNHN0021.
Coelacanths (Actinistia) form a clade of lobe-finned vertebrates that are nowadays represented by a single genus, Latimeria. In this thesis, I first present a redescription of poorly known fossil coelacanths Trachymetopon and Megalocoelacanthus from the Jurassic and Cretaceous periods. These fossils give new insights into the phylogenetic relationships and paleobiogeography of the Mesozoic coelacanths. Moreover, they shed light on the variability in the skull anatomy in large-sized, fossil coelacanths. Then, I present unique data on the early development of the extant coelacanth Latimeria based on X-ray synchrotron microtomography, and discuss of the importance of developmental data to our understanding of the evolution of the cranial system in coelacanths. Investigation of the functional significance of the morphological variation in skull anatomy is also needed to understand the evolutionary trade-offs in the cranial system of coelacanths, and to make inferences on the feeding behavior and ecology of fossil coelacanths. However this objective first necessitates an in-depth understanding of the skull mechanics in the extant coelacanth Latimeria, which is investigated in the rest of this thesis. Among extant vertebrates, Latimeria is unique in having a skull divided into an anterior and a posterior part, articulated by means of an intracranial joint. This joint is associated with a paired muscle, the basicranial muscle. This complex articulation was previously thought to allow an elevation of the snout by 15° to 20°, which would enhance mouth opening distance and allowing the animal to perform a powerful suction. The basicranial muscle was thought to depress the anterior portion of the skull from its elevated state during mouth closure. I re-describe the musculo-skeletal anatomy of the skull based on the dissection of an adult coelacanth specimen. These new data suggest that the intracranial joint and the hyoid apparatus are less mobile than previously thought. The elevation of the anterior portion of the skull is unlikely. However, a small but distinct ventroflexion of the anterior portion of the skull from its resting position under the action of the basicranial muscle is likely based on the anatomy of the joint. Using a static equilibrium model, I show that the basicranial muscle increases the overall bite force generated by Latimeria, suggesting that the role of a functional intracranial joint in coelacanths may be associated with bite force generation rather than suction feeding. Preliminary results of finite element analysis on biting in Latimeria, as well as future research directions are finally presented. The understanding of the skull mechanics in Latimeria will serve to investigate in future work the functional implications on feeding of the variations in skull anatomy described in fossil coelacanths
Charles, Cyril. "Evo-Dévo des dents chez les rongeurs murinés : des gènes à la morphologie". Poitiers, 2008. http://www.theses.fr/2008POIT2330.
Among mammals, tooth rows are an ideal model to study mechanisms linking evolution and developmental biology. Many genes involved in dental development have already been identified in the laboratory mouse. However, the function of these genes in the course of evolution remains highly unknown. This thesis aims at identifying developmental genes involved in dental evolution among mammals and particularly among rodents. In a first part, various dental anomalies occurring among wild populations of eutherian mammals are presented and are discussed regarding dental development models. These anomalies also underline various evolutionary trends among eutherian mammals. In a second part, dental anomalies associated to losses of functions of two Eda pathway genes (Eda and Edar), are deeply investigated. This study brings to the fore new information on the function of these two genes on odontogenesis. The results also show that the Eda signaling pathway is potentially involved in dental evolution among rodents, particularly in the acquisition of the muroid dental formula. Morphological comparisons between Eda pathway mutants and various extent rodent species indicate a potential implication of this pathway in the setting up of the atypical dental morphology of Rhynchomys (Muridae, Rodentia). Eventually, a preliminary study of the tooth morphology of mice carrying losses of functions of the Fgf3 gene and its antagonists, Sprouty2 and Sprouty4, indicates a potential implication of these genes in the acquisition of the murin dental plan and some similarities with primitive murid species. All of the results indicate that the studied genes involved in dental development may also be implicated in the dental modifications in the course of evolution among Muroidea
Isnard, Sandrine. "Biomécanique et évolution de la forme grimpante chez les palmiers (Arecaceae)". Montpellier 2, 2005. http://www.theses.fr/2005MON20214.
The climbing growth form has appeared several times during palm evolution and in phylogenetically distant groups. Among the 2700 species recognised in the Arecaceae, more than 500 are climbers. This study deals with species belonging to the two subfamilies, which include climbing forms, the Arecoideae and the Calamoideae, from South America and South-east Asia respectively. The main objective is to understand the mechanical, morphological and developmental traits linked to the climbing habit in a family that lacks secondary growth. The results are discussed using recent phylogenetic reconstructions and are compared with previous studies on the mechanical architecture of dicotyledonous lianas. The first part deals with the mechanical architecture and development of axes. The results emphasize the mechanical role of the leaf sheath and specific adaptations of the stem for the climbing habit in each subfamily. In the second part, morphological and structural organisation of attachment organs (flagellum and cirrus) are investigated. Breaking forces of hooks and acanthophylls, and the variations of mechanical properties along cirri and flagellae are discussed in terms of the plant ecology, its potential for occupying space and its attachment to supports. The results suggest that the apparently strongly convergent evolution towards the climbing habit has in fact produced specific mechanical architectures according to the phylogenetic constraints of different genera. In both subfamilies the occurrence of the climbing growth form may have resulted from heterochronic processes, involving the reduction of the establishment phase that characterise arborescent palms
Rousset, Vincent. "Phylogénie moléculaire et morphologique des annélides". Paris, Muséum national d'histoire naturelle, 2004. http://www.theses.fr/2004MNHN0005.
Interrelationships among the major Annelida groups remain unresolved, although addressed earlier both in molecular and morphological studies. We attempted to answer to some of these issues in four studies. (1) Combined parsimony analyses of 28S rRNA and morphological data to assess the relationships of Alvinellidae, a group known only from deep-sea hydrothermal vents. Our results indicate that : Trichobranchidae is separate from Terebellidae and may be the sister of Alvinellidae, and Ampharetidae and Terebellidae are monophyletic but require further attention. (2) We assessed the phylogenetic position of Siboglinidae (the previous phyla Pogonophora and Vestimentifera, but now nested within polychaetes). Combined parsimony analyses of molecular (18S and 28S rRNA) and morphological data provide strong support for a sister-group relationship between Siboglinidae and Oweniidae, and for the monophyly of Terebelliformia, but demonstrate that the delineations of Terebellida and Sabellida require further study. (3) Based on 18S, 28S and 16S rRNA sequences, we analysed relationships and position of clitellates (earthworms and leeches). Parsimony and bayesian analyses indicate that clitellates have a sistergroup within polychaetes, consisting of a subgroup of a polyphyletic Scolecida, but also delineation problems with polychaetes and annelids. (4) Results obtained from parsimony and bayesian analyses of 117 terminals and 18S, 28S, 16S rRNA and histone H3 sequences indicate polyphyly of Annelida, owing to the nested positions of one sipunculan, one nemertean, one brachiopod and two molluscs, polyphyly of major groups of polychaetes and corroborate the results of the third study on the position of Clitellata
David, Romain. "Le système des canaux semi-circulaires des archosaures : anatomie, morphométrie, morphologie fonctionnelle, évolution". Paris, Muséum national d'histoire naturelle, 2011. http://www.theses.fr/2011MNHN0038.
Semicircular canals are peripheral organs of the vestibular system which are specialised in the detection of head rotations. The signals they transmit to the central nervous system are integrated with visual, proprioceptive and other vestibular signals in order to provide a stable reference frame through head and visual field stabilisation. This allows navigation, motor control and optic flow integration to optimally occur, particularly during locomotion. Here I provide a new methodological framework to analyse the vestibular capabilities of extant and extinct taxa, based on the functional structure of the semicircular canals' system (SCFS). The calculation of the SCFS takes the most of semicircular canals' morphology and empirical relations retrieved upon membranous labyrinths. It provides us with the estimated in-plane sensitivity and maximal response axis of each semicircular canal. This new methodological framework allows us to study absolute and relative overall sensitivity of a semicircular canals' system, along with its directional sensitivity and coding patterns. Data from computed tomography scanning of extant and extinct specimens allow us to reconstruct, to describe and to analyse the bony labyrinth of 39 archosaurs and the membranous labyrinth of 5 tetrapods. We provide evidence that the semicircular canals carry a phylogenetic informative signal, and we retrieved the dinosaurian origin of the clade Aves based on semicircular canals' characters only, for the first time. We show that the shape of the semicircular canals of archosaurs is correlated with the phylogenetic position of the specimens, but also with their biomechanical capabilities, suggesting that the diversification of the archosaurs came along with biomechanical adaptations of the inner ear. We demonstrate that the semicircular canals' system detects some rotations more precisely than others, and that there exist numerous patterns of detection that could eventually be correlated with locomotor repertoires. Finally, we find that birds using flapping flight present an optimisation toward a decrease in the biomechanical sensitivity of their semicircular canals' system, and we deduce from this analysis that the semicircular canals‟ system of Archaeopteryx does not theoretically prevent it to perform flapping flight
Eléaume, Marc. "Approche morphométrique de la variabilité phénotipique : conséquences systématiques et évolutives : application aux crinoïdes actuels (Crinoidea : Echinodermata)". Paris, Muséum national d'histoire naturelle, 2006. http://www.theses.fr/2006MNHN0031.
The taxonomy and evolutionary history of crinoids (Crinoidea: Echinodermata) are based on skeletal features which are known to vary as a function of size, age or environmental conditions. Classical multivariate morphometry applied to comatulids allows proposing taxonomic hypothesis which can be tested by the analysis of discrete characters. Florometra mawsoni and Solanometra antarctica are congeneric. Florometra asperrima and F. Serratissima are conspecific. The structure of the calix and articular facets display synapomorphies. Promachocrinus kerguelensis shows two different morphotypes that are differently distributed in the biogeographical provinces of the Southern Ocean. Notocrinus virilis and N. Mortenseni are not congeneric. Comatulids are replaced among the crinoids using a combined analysis of morphological and molecular characters. Primary homologies are tested and homoplasies discussed
Falconnet, Jocelyn. "Diversification initiale des amniotes : l'apport des amniotes français". Paris, Muséum national d'histoire naturelle, 2010. http://www.theses.fr/2010MNHN0035.
Mignot, Yannick. "Un problème de paléobiologie chez les ammonoïdes (Cephalopoda) : croissance et miniaturisation en liaison avec les environnements". Lyon 1, 1992. https://tel.archives-ouvertes.fr/tel-02426776/document.
Bienvenu, Thibaut. "L'Endocrâne de Sahelanthropus Tchadensis (Hominidae, Miocène supérieur du Tchad) : reconstitution 3D et morphologie : comparaison avec les hominoïdes actuels et fossiles". Poitiers, 2010. http://theses.univ-poitiers.fr/26582/2010-Bienvenu-Thibaut-These.pdf.
The fossil cranium of Sahelanthropus tchadensis, nicknamed Toumaï, was discovered in 2001 at Toros-Menalla (Chad). Currently, it is the oldest known hominid, dated at 7 Ma. It is very close, temporally and phylogenetically, to the dichotomy between humans and chimpanzees. Using synchrotron X-ray imaging techniques, fragmented inner table was virtually extracted out of the matrix filling the skull. Postmortem distortions of the endocranial surface have been corrected. Finally, filling the gaps resulted in the virtual endocast of the oldest known hominid. The endocast of Toumaï gives a first insight into the morphology of the brain of Late Miocene hominids. Comparison with a sample of extant and fossil primates, using both traditional and geometric morphometrics methods, enabled assessing primitive and derived endocranial traits of these hominids. The hypothetical endocranial morphology of the last common ancestor to humans and chimpanzees differs from those of extant great apes in many aspects, notably greater relative length, frontal lobes more stretched medio-laterally, and cerebellar lobes less protruding posteriorly, confirming that extant great apes are not good proxies to infer hominid primitive morphology. The endocast of Toumaï is characterized by a flexed cranial base and occipital lobes strongly protruding posteriorly. These structural changes provide new clues of the bipedal locomotor mode of Sahelanthropus tchadensis. The endocast of Toumaï does not show any clear feature of neural reorganization
Chevret, Pascale. "Etude évolutive des "Murinae" (rongeurs : mammifères) africains par hybridations ADN/ADN. Comparaisons avec les approches morphologiques et paléontologiques". Montpellier 2, 1994. http://www.theses.fr/1994MON20165.
Lauters, Pascaline. "Structure générale et évolution du cerveau chez les dinosaures ornithischiens". Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209390.
Une nouvelle phylogénie a été établie, bénéficiant de l’apport de nouveaux caractères basés sur l’endocrâne. Elle apporte des éléments de réflexion intéressants quant à la position de plusieurs taxons d’Iguanodontia basaux. La résolution est cependant faible et d’autres études devront être menées dans le futur. Les relations de parenté ne sont pas stables et de faibles changements entraînent des différences notables dans les résultats des analyses phylogénétiques./Among the Dinosauria, Ornithopoda were one of the most successful clade. Since the Late Jurassic, they spread and diversified until the end of the Cretaceous. I studied the brain of Ornithopoda from Europe and Asia, established comparisons with other archosaurs and new phylogenetic analyses including endocranial characters. In order to do this, I made silicone endocasts of 3 taxa and virtual reconstructions from CT-scan dataset of 3 other taxa of ornithopod dinosaurs. A collection of extant crocodiles and birds allows more points of comparison. Some endocasts made on the fossil specimens confirmed previously described characteristics, while new ones were brought to our attention. The endocasts opened up not only the morphology of the brain, but also the anatomy of the cranial nerves, the pituitary gland and the presence of valleculae. This last element, evidence of a developped telencephalon, has been established in a new Hadrosauroidea species as his oldest occurrence. The brain of more derived Ornithopods was characterized by very large cerebral hemispheres. The pontine and cranial flexures disappeared, to the contrary to what is observed in Saurischians. The olfactory peduncles were large. New evidences about the correlation between the size of the pituitary gland and the size of the individual. The Ornithopod’s brain changed throughout their evolution :the most striking is the increase of the cerebral hemispheres. The complexity of behaviors exhibited by Ornithopods is suggested as the trigger of the increase of the size of the cerebral hemispheres.
A new phylogenetic analysis was established, including new characters from the endocranial cavity. It brings interesting perspectives about the position of several basal Iguanodontia. Unfortunately the resolution is weak and new studies will be needed. The relationships are not stable and small changes lead to instabilities in the result of the phylogenetic analysis.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Boucher, Stéphane. "Évolution et phylogénie des coléoptères Passalidae (Scarabaeoidea) : les taxons du groupe famille : la tribu néotropicale des Proculini et son complexe Veturius". Paris, Muséum national d'histoire naturelle, 2005. http://www.theses.fr/2005MNHN0007.
Belouze, Anne. "Compréhension morphologique et phylogénétique des taxons actuels et fossiles rapportés aux anguilliformes (poissons, téléostéens)". Lyon 1, 2001. http://www.theses.fr/2001LYO10237.
Huchon, Dorothée. "Phylogénie moléculaire des rongeurs (Mammalia, Rodenta) : contribution de gènes nucléaires et confrontation avec les données mitochondriales". Montpellier 2, 2000. http://www.theses.fr/2000MON20199.
Kruta, Isabelle. "Étude de la masse buccale des ammonites : implications paléobiologiques et évolutives". Paris, Muséum national d'histoire naturelle, 2011. http://www.theses.fr/2011MNHN0031.
The buccal mass of ammonites can be used for paleobiological and phylogenetical studies. The exploration of the body chamber of exceptionally well-preserved specimens allowed to discover new buccal mass elements in Didymoceras, Rhaeboceras and Baculites and a new type of microstructre was identified in ammonites. Thanks to 3D imaging, used for the first time in ammonites (CTscan, PPC-SR-μCT), the morphology of the radula could be observed in three specimens of Baculites and one specimen of Rhaeboceras. After the morphological analyses of the jaw elements and the comparison with recent cephalopods, it was suggested that ammonites with aptychus jaws fed on organisms belonging to the plankton sl. , and more precisely zooplankton. It was reinforced by the discovery of organisms rests that could belong to the zooplankton in the buccal mass of one specimen of Baculites
Prosperi, Juliana. "Biologie du développement des hémi-épiphytes ligneux". Montpellier 2, 1998. http://www.theses.fr/1998MON20240.
Poveda, Maria Marcela. "Variabilité biochimique et morphologique de Juniperus communis L dans le sud de l'Europe". Toulouse 3, 2003. http://www.theses.fr/2003TOU30004.
Dubuisson, Jean-Yves. "Systématique du genre "Trichomanes" (Filicopsida, Hymenophyllaceae) : confrontation et combinaison des données anatomo-morphologiques, cytologiques et moléculaires". Montpellier 2, 1996. http://www.theses.fr/1996MON20183.
Alapetite, Elodie. "Etude de l’appareil reproducteur des palmiers (Arecaceae) : évolution du système sexuel et du nombre d’étamines". Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112063/document.
Palms (Arecaceae) are an emblematic family of monocots of 183 genera and around 2500 species distributed on all continents, throughout tropical and subtropical areas. Their characteristic leaves and stems make palms immediately recognizable in the field. The inconspicuous palm flowers are usually considered as rather dull. They are usually small (a few centimetres), trimerous, often unisexual, colourless (white or greenish) and grouped into huge inflorescences. However palms exhibit a large diversity in sexual system and in stamen number, diversity that is still poorly understood. The three main sexual systems of angiosperm, hermaphroditism, dioecy and monoecy are present in palms. Stamen number ranges between a few units (oligandry) to several dozens and even several hundreds of units (polyandry) in some genera. We studied the evolution of sexual system and stamen number at the family level. We used as historical framework a well-supported and dated phylogeny, published recently. Our study showed that the putative ancestor of palms was monoecious and bore oligandrous flowers with 6 stamens. From these ancestral states, several transitions occurred: towards hermaphroditism and dioecy and towards polyandry respectively. In order to initiate a research on a possible functional significance of increase in stamen number, we investigated the relationship between stamen number and pollen production, by extracting the total pollen content from flowers of 82 species. Our study showed a tendency towards higher pollen production when the number of stamen increases in two subfamilies. We also produced molecular phylogeny of a subtribe (Ptychospermatinae) in which the range of variation in stamen number is exceptional. Further investigations into genetic, developmental, ecology and pollination biology are needed
Bignon, Arnaud. "Évolution morphologique et associative des trilobites sous contrainte environnementale, au Dévonien moyen et supérieur, en Ardenne occidentale (bord sud du Synclinorium de Dinant)". Electronic Thesis or Diss., Lille 1, 2011. http://www.theses.fr/2011LIL10107.
The study of trilobites of Middle and Upper Devonian from Ardenne Massif and Boulonnais contributes in multiple ways to the improvement of our understanding of the Life and Earth’s history of this period. Their biodiversity has been explored from multivariate statistical analyses. A gradually organisation of the structure of their communities has been evidenced. Indeed, in the same reefal platform context, only one association is presented in whole Givetian environments, whereas two associations have been identified at the Frasnian, the one confined to reefal build-ups and the other to perireefal facies. An analysis of Givetian megaguilds underlines the particularity of reefal environments compared to the other ones of the platform. Developmental description of three Dechenella species, through a geometric morphometry analysis, allows us to identify several evolutionary changes of ontogeny on cephala and pygidia. This work illustrates the complexity and the importance of ontogenetic changes in new morphology production. Phylogenetic study of Asteropyginae allow us to propose a new vision of their evolutive history. Traditionally splitted in two separate clades, the cladistic analysis of this subfamily shows a more progressive evolution in one clade. Moreover, a new origin has been suggested through the genus Destombesina. From these results, pygidial and cephalic patterns, at the base of the systematic of this group, have been redefined
Toghranegar, Zohreh. "Diversité et évolution de la microsporogenèse chez les angiospermes basales et les monocotyledones". Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112110.
The pollen grain, the male gametophyte of seed plants, is the product of microsporogenesis (male meiosis). It has a considerable structural diversity in flowering plants. To investigate this diversity, we have focused our study on the aperture pattern. The aperture pattern of pollen grains is defined by the shape and number of apertures, and their position when pollen grains are still assembled in tetrads at the end of meiosis. The outer pollen wall is punctuated with apertures, areas where the exine is thinner or even absent. The apertures are the places where the pollen tube emerges at germination. They also have an essential functional role for the survival of pollen grains. The study of microsporogenesis has shown that variations in the aperture pattern can be correlated with features of this developmental process: the type of cytokinesis, the tetrad shape, the way in which callose walls are formed among the four microspores and the position of the apertures within the tetrad (polar or grouped at the last point of contact among the microspores). Recently, in a certain number of species, a correlation has been evidenced between the location of the last points of additional callose deposition and aperture location after wall formation among the future microspores. We studied the diversity and evolution of the above-mentioned features of microsporogenesis and additional callose deposition at the late tetrad stage in a selection of species from basal angiosperms and monocots (with a particular sampling effort in Bromeliaceae) with various aperture patterns. The study of microsporogenesis in these groups revealed the presence of additional callose deposits in most cases. We show that there is a link between the last points of callose deposition and aperture location for several aperture types. In addition, for the same pollen morphology, we have observed different patterns of callose deposition. We described seven different microsporogenesis pathways associated to monosulcate pollen grain. They differ in the type of cytokinesis, tetrad shape, and presence and shape of additional callose deposition. Using Maximum Parsimony, we reconstructed the evolution of the features of microsporogenesis and the presence or absence of additional callose deposits likely to play a key role in aperture pattern determination. Our results confirm that the shape of tetragonal tetrads, in association with the successive cytokinesis, centrifugal cell wall formation, and the presence of additional callose deposits, is the ancestral states in monocots. Using our results on basal angiosperms, we confirm that tetrahedral tetrad, in association with simultaneous cytokinesis, centripetal cell wall formation, and the presence of additional callose deposits, are ancestral at the level of angiosperms. Our results highlight the large variability of the features of microsporogenesis in our study species. The transitions observed in the tetrad form character associated in the most cases with transitions in the cytokinesis character, confirm the relationship between these two characters. The transitions in intersporal wall formation are associated with transitions in all other characters. This suggests a correlation among the different components of microsporogenesis in angiosperms. On the opposite, the presence of additional callose deposits, which seems to be the key element in aperture pattern determination (contrary to previous hypotheses) is disconnected from the other features of microsporogenesis. The variations additional callose deposits leading to monosulcate pollen show that the development (additional callose deposits) is not due to developmental constraints and stasis on monosulcate apertural pattern is resulting from selective pressures
Bignon, Arnaud. "Évolution morphologique et associative des trilobites sous contrainte environnementale, au Dévonien moyen et supérieur, en Ardenne occidentale (bord sud du Synclinorium de Dinant)". Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10107/document.
The study of trilobites of Middle and Upper Devonian from Ardenne Massif and Boulonnais contributes in multiple ways to the improvement of our understanding of the Life and Earth’s history of this period. Their biodiversity has been explored from multivariate statistical analyses. A gradually organisation of the structure of their communities has been evidenced. Indeed, in the same reefal platform context, only one association is presented in whole Givetian environments, whereas two associations have been identified at the Frasnian, the one confined to reefal build-ups and the other to perireefal facies. An analysis of Givetian megaguilds underlines the particularity of reefal environments compared to the other ones of the platform. Developmental description of three Dechenella species, through a geometric morphometry analysis, allows us to identify several evolutionary changes of ontogeny on cephala and pygidia. This work illustrates the complexity and the importance of ontogenetic changes in new morphology production. Phylogenetic study of Asteropyginae allow us to propose a new vision of their evolutive history. Traditionally splitted in two separate clades, the cladistic analysis of this subfamily shows a more progressive evolution in one clade. Moreover, a new origin has been suggested through the genus Destombesina. From these results, pygidial and cephalic patterns, at the base of the systematic of this group, have been redefined
Millien, Virginie. "Taille des incisives et structure de taille des communautés de rongeurs : aspects écologiques et évolutifs en milieu insulaire". Montpellier 2, 1999. http://www.theses.fr/1999MON20225.
Fougère-Danezan, Marie. "Phylogénie moléculaire et morphologique des Detarieae résinifères (Leguminosae : Caesalpinioideae) : contribution à l'étude de l'histoire biogéographique des légumineuses". Thèse, Toulouse 3, 2005. http://hdl.handle.net/1866/6594.
Cao, Vien. "Contribution à l'étude des péridiniens d'eau douce : Isolement de clones, culture, nutrition. Quelques aspects inconnus ou peu connus de la biologie de ces algues". Paris 7, 1987. http://www.theses.fr/1987PA077098.
Botton, Léo. "The Form-Function relationships in the process of secondary adaptation to an aquatic life : the contribution of semi-aquatic mammals". Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC087/document.
Moving in water and on land implies coping with drastically different mechanicalconstraints. Water is substantially more dense and viscous than air and thus aquaticlocomotion is dominated by drag and buoyancy when terrestrial locomotion is dominatedby gravity and inertia. If extreme adaptations to locomotion in each of thesetwo media are well described, semi-aquatic species that move extensively in bothmedia remain poorly studied.Mustelids presents a large diversity of locomotor specializations involving differentkinds of locomotor environments and different degrees of specialization. It encompassthree independent evolutions of a semi-aquatic lifestyle: the European mink,the American mink, and the otters. Using geometric morphometrics to quantify theshape of the entire humerus, radius, ulna, femur, tibia, and fibula I investigated morphologicaldifferences in the locomotor apparatus of terrestrial and semi-aquaticmustelids. As both minks and otters face functional pressures resulting from bothaquatic and terrestrial locomotion, I tested whether their morphology converged.Finally, considering the differences in the functional requirements of the two media,I explored whether the locomotor ecology has a homogeneous impact on thelocomotor apparatus or whether a functional specialization of certain parts can beobserved.Whereas minks show low morphological differentiation from their terrestrial relatives,otters diverged a lot in both shape, size, and the relative proportions of thelimb bones. Minks present a morphology that is similar to the one observed in otherMustelinae. Nevertheless, the shape of the humerus is convergent between thetwo minks, and shows a greater curvature than in their terrestrial relatives. Minksresult from recent specializations of the versatile morphology of Mustelinae witha swimming mode similar to the one of the terrestrial Mustelinae and only subtlemodifications of their long bone morphology.Conversely, otters present a long bone shape that is strongly divergent from theone of their terrestrial relatives. Additionally, they show very diverse long boneshapes in opposition to the hypothesis stating that strong functional requirements,as the ones induced by aquatic locomotion, should induce a limited number of potentialevolutionary responses. Otters show morphological features that are related to aquatic locomotion: robust bones with broad epiphyses, a short stylopodrelative to the zeugopod, and a long in-lever for elbow extensors. Only the sea otter(Enhydra lutris) presents a functional specialization that differs between hind andforelimb. The hind limb is dedicated to aquatic locomotion with a strong in-lever forthe hip muscles, and the feet that are modified into swimming paddles. Meanwhile,the forelimb presents a relatively gracile ulna with a short olecranon process and aradius that is curved more cranially, resulting in a drastic change in the pattern ofco-variation. These features are interpreted as providing greater degrees of freedomin the movements of the forearm, which allows the unique manipulative skillsof this species.Thus semi-aquatic mustelids present a diversity that was not expected given thestrong differences in the mechanical constraints imposed during locomotion in waterversus on land. Semi-aquatic mustelids appear to have evolved from the versatileancestral locomotor apparatus to highly specialized forms, where the progressivereduction of terrestrial locomotion allowed differential adaptation of the foreandhind limbs
Petit, Daniel. "Contribution à l'étude de l'évolution des Carduées et Lactucées (Composées)". Montpellier 2, 1990. http://www.theses.fr/1990MON20127.
Meunier, Mathias. "Biodiversity, biostratigraphy, disparity and macroecology of middle Eocene radiolarians (Rhizaria) : insights to their biotic response to the Middle Eocene Climatic Optimum (MECO)". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR078.
The Middle Eocene Climatic Optimum (MECO) is a global warming event that occurred ca. 40 Ma and temporarily interrupted the long-term Eocene cooling trend. Although the MECO represents one of the larger climatic disruptions of the Paleogene, its impact on the biosphere is still poorly understood. Based on a wide range of quantitative methods, this thesis aims to study the radiolarian paleodiversity dynamics and morphological disparity through the MECO, in order to gain a deeper understanding of the biotic perturbations associated with this climatic event. The taxonomic understanding of middle Eocene radiolarian species was first clarified, by documenting at the species level two well-preserved radiolarian faunas recovered from two distinct geographic regions: the equatorial Atlantic (ODP site 1260) and the North Atlantic (ODP site 1051). A total of 276 species were identified, including 37 new to science. Taking advantage of the cyclostratigraphic framework developed at Site 1260, we refined the global tropical radiolarian biozonation. The absolute ages of 71 radiolarian bioevents were calibrated and, by comparison with the equatorial Pacific record, the synchroneity of primary bioevents was demonstrated. Once the taxonomic and biostratigraphic frameworks were clarified, the main aim of this thesis was to assess the radiolarian biotic sensitivity to climate change. Two categories of metrics were used to achieve this objective. On the one hand, we performed a whole assemblage quantitative analysis at ODP Site 1051. This detailed investigation of the radiolarian fauna did not reveal any prominent turnover during the MECO, but only a slight increase in radiolarian taxic richness due to the poleward migration of several tropical radiolarian species. On the other hand, we applied geometric morphometric approaches to quantify the morphological disparity of radiolarian shell through the MECO interval. This study was focused on a single species (Podocyrtis papalis) from Site 1260, and showed that fluctuations in morphological disparity coincide with the warmest interval of the MECO. This signal is interpreted as an indicator of biological stress induced by the warming event
Laporte, Martin. "Histoire évoutive et phylogéographie de la colonisation des eaux douces par une espèce d'origine marine, la blennie fluviatile (Salaria fluviatilis)". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20113.
The freshwater blenny (Salaria fluviatilis) colonised the freshwater environment from a marine ancestor and now inhabits lakes and rivers around the Mediterranean Sea. How this important environmental change affected the genetic structure and the phenotype of this species ? It is around this central question that two major axes will be developed in this thesis. The first axis focus on the consequences of historical geologic events that affected the genetic structure of S. fluviatilis. It will be show that the northern locations of the Occidental basin of the Mediterranean sea were colonised from two different glacial refuges. The second axis focus on the adaptation and acclimation required to colonise a new environment. It will be show that the reponses of body shape and fins length of S. fluviatilis to water velocity are controlled by an environmental determinism. Together, these two axes will allow for a better understanding of populations differentiation process following the colonisation of a new environment
Labonne, Gaëlle. "Modèle de développement et évolution du patron dentaire chez les rongeurs actuels et fossiles : radiation adaptative et émergence de phénotype : le cas des Arvicolinae (Rodentia)". Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS086/document.
The evolution of mammalian dentition is defined by profound morphological modifications as occlusion and heterodonty. Among rodents, characterized by a reduced dental formula, arvicolines have a highly derived dentition, with prismatic and hypsodont molars. The aim of this Ph.D thesis is to explore various morphological innovations through developmental and adaptive aspects. Geometric morphometric methods were used on molars, incisors and mandibles to investigate the dynamics of development and evolution of dentition. A developmental model predicting molar proportions is tested and confirmed for the rodent order; it could be also extended to the premolar. The relationship between dental morphology, in particular molar proportions, and diet is complex, diet being not directly inferred from one morphological trait. Yet, covariations between molars inform on masticatory movement and thus on function. Our results confirmed that morphologies could be understood from a complex combination of historical, functional and developmental constraints. The various structures of the mandible have a complex hierarchical organization. The development of mammalian dentition is controlled by similar processes but through times, mechanisms as heterochrony may lead to a diversification of phenotypes
Massoni, Julien. "Phylogeny, molecular dating and floral evolution of Magnoliidae (Angiospermae)". Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01044699.
Dang, Le Anh Tuan. "Ontogenetic variations in leaf traits of the homoblastic species Dipterocarpus alatus under two light conditions at Cat Tien national park, Vietnam". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20236/document.
Background and Aims:Attempts to explain variations in leaf parameters based solely on environmental factors, this will lead to significant errors if the plant shows substantial ontogenetic variations in leaf properties. We evaluated variations in 27 morpho-anatomical leaf traits of Dipterocarpus alatus over six architectural development stages and between axes at a given development stage under two different light conditions. Methods:An architectural analysis was conducted to distinguish precisely and objectively axis categories and developmental stages of Dipterocarpus alatus. Leaves were collected on the most recent complete growth unit on the top of the trunk and the outermost part of the middle-crown branch with branchlet and twig from trees growing under two different light conditions. Twenty two leaf traits were measured and calculated using ImageJ on images of leaf tracings and cross-sections. Stomatal density was calculated on nail varnish impression of the leaf lower surface. Four chlorophyll traits were determined. One-way ANOVA and Tukey post-hoc tests were used to determine differences between development stages and axes. The lmg relative contribution was calculated with R package relaimpo and compared with bootstrap analysis to determine ontogenetic stage, axis category or light intensity, which explained more the variations in leaf anatomy.Key results:Leaf morphology and anatomy differed strongly during ontogeny for all four axes in term of order and category under both light conditions. The axis effect was displayed at stages B, C, D and F but tend to be insignificant at stage E. Tree ontogeny explained more variations in leaf morphology and anatomy than light intensity. Axis category explained more variations in leaf morphology but not in leaf anatomy than tree ontogeny. Conclusions: Strong and significant intraspecific variations (during ontogeny and between axes) may influence the interspecific variations, and thus challenge the validity of the mean value of leaf traits between species. Tree ontogeny contributed more than light intensity in explanation of the variability in leaf morphology and anatomy both on the trunk and second axis order strongly recommends that studies on the responses of leaf anatomy to the environment need to correct for the ontogeny effect
Reyes, Elisabeth. "Evolutionary history of floral key innovations in angiosperms". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS489/document.
Angiosperms are a clade known for its great species diversity and the uneven distribution of this diversity among its lineages. This work focuses on the ancestral state reconstruction of floral characters on phylogenies in the purpose of studying their impact on diversification. We first focused on two potential key innovations in Proteaceae, bilateral perianth symmetry and presence in Mediterranean-climate hotspots. Using character state dependent diversification models, we found that the first character state did not have any significant impact on species diversification in this group, contrary to the second one. We then reconstructed ancestral states for perianth symmetry in angiosperms as a whole, using a sampling strategy aimed at capturing all of the transitions in this character. We found a minimum of 130 origins of bilateral symmetry, followed by 69 subsequent reversals to radial symmetry. Lastly, the same approach was extended to the study of four other perianth characters. Different ancestral state reconstruction models were used on a phylogenetic tree of 1232 species to test the influence of model changes on reconstructed ancestral states. Our results show that changes in reconstruction models have an impact on the inferred ancestral state of some nodes, but not all of them. The various results obtained for symmetry, a character shared among the three chapters, indicate that our sampling method has the drawback of estimating transition rates too high to give conclusive results with maximum likelihood. On the other hand, results are much less biased when several characters are examined simultaneously
Laugier, Thierry. "Ecologie de deux phanérogames marines sympatriques "Zostera marina L. " et "Zostera noltii Hornem. " dans l'étang de Thau (Hérault, France)". Montpellier 2, 1998. http://www.theses.fr/1998MON20170.
Godbout, Marie-Andrée. "Développement ontogénique de deux populations d'éperlan arc-en-ciel (osmerus mordax) de l'estuaire moyen du St-Laurent". Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/26622/26622.pdf.
Gonzalez, Paul. "Morphologie évolutive et fonctionnelle des hémichordés". Thèse, 2010. http://hdl.handle.net/1866/4962.
The phylum Hemichordata comprises the classes Enteropneusta and Pterobranchia. Together with echinoderms, hemichordates are the sister-group to chordates. Enteropneusts are worm-shaped solitary deposit feeders. Pterobranchs are colonial filter feeders that live in a secreted collagenous domicile called a coenecium. In this thesis, three studies are presented. These studies are based on observations of extant hemichordates, and adress a variety of issues relating to the evolution of hemichordates, chordates, and the super-phylum to which they belong: Deuterostomia. Our first study demonstrates that the gill slits, pre-oral ciliary organ (POCO), and lining of the pharynx of the enteropneust Protoglossus graveolens are used in filter feeding. The filter-feeding system of P. graveolens enables particle capture down to 1.3 um, at a rate up to 4.05 mm.s-1, with a power consumption of 0.009 uW. Structural and functional similarities with the cephalochordate filter-feeding system suggest that pharyngeal filter-feeding is ancestral to the deuterostomes. In our second study, we address the hypothesis that the enteropneust POCO, a putative chemosensory structure located anterior to the mouth, is homologous to the cephalochordate wheel organ and vertebrate adenohypophysis. We characterized the expression pattern of the adenohypophysis-specific transcription factor Pit-1 in the adult enteropneust Saccoglossus pusillus with immunohistochemistry. Pit-1 is expressed in sensory cells of the POCO and in scattered epithelial cells of the proboscis, collar and trunk. This expression pattern does not allow to confirm or reject the homology of the POCO with the vertebrate adenohypophysis. In our third study, we characterized the ultrastructure of the coenecium of the pterobranchs Cephalodiscus hodgsoni, Cephalodiscus nigrescens and Cephalodiscus densus using transmission and scanning electron microscopy. Cephalodiscus is the sister-group to the Graptolithina, which includes the extinct graptolites and the extant pterobranch genus Rhabdopleura. We described the fibril types, size and organization, as well as the general organization of the coenecium. We demonstrated that the coenecium of Cephalodiscus shows similarities with the graptolite eucortex, paracortex and pseudocortex. The cortical-like organization of the coenecium of Cephalodiscus suggests that the cortex is ancestral to the Pterobranchia. Together, these three studies illustrate different axes of hemichordate research, and show how integrating morphological, functional and molecular data allows us toinfer key events in the evolution of deuterostomes.