L'ordre des rongeurs (Rodentia) est le groupe de mammifères le plus riche en espèces, les muroïdes étant la superfamille la plus diversifiée. Comme ils occupent des niches écologiques arboricoles, semi-aquatiques, souterraines et terrestres, les rongeurs peuvent présenter des traits morphologiques reflétant leurs adaptations à des environnements aussi divers. Cette thèse porte sur la morphologie de l'endocrâne, de la bulle auditive et de la cochlée dans trois tribus (Otomyini, Taterillini et Gerbillini) représentant 10 espèces de rongeurs africains, en se concentrant sur la variabilité de ces traits, leur fonction et leur adaptabilité, à l'aide d'imagerie par micro-scanner et de méthodes de comparaison de formes tridimensionnelles. De plus, les variations de la taille du crâne ont également été étudiées en fonction du réchauffement climatique et des variables climatiques. Les changements / variations morphologiques sont liées à des différences environnementales. Par conséquent, chaque chapitre de cette étude détaille l'effet des changements environnementaux (dans l'espace et dans le temps) sur différents traits morphologiques, c'est-à-dire la taille générale du crâne (chapitre 2), la cochlée et les bulles auditives (chapitre 3), et la taille et la forme endocrânienne (chapitre 4). Le chapitre 2 traite spécifiquement du changement climatique au sens strict et les deux autres chapitres traitent de différents gradients environnementaux. Le chapitre 2 teste l'applicabilité de la "troisième réponse universelle au réchauffement" (c'est-à-dire de la diminution de la taille corporelle) et de la "règle des ressource" dans deux sous-familles de muridés, Murinae et Gerbillinae. L'étude montre que la troisième réponse n'est pas universelle puisqu'une seule espèce s'est conformée à ce type de réponse. De plus, il a été démontré que la disponibilité de nourriture (règle des ressources) était un facteur plus important que la règle de Bergmann pour expliquer les corrélations entre variations de l'environnement et celles de la taille des espèces de rongeurs.[...] / The order Rodentia is the most speciose group of mammals with muroids being the most diverse superfamily. Since they are represented in arboreal, semiaquatic, subterranean and terrestrial niches, rodents may exhibit morphological traits reflecting their adaptations to such diverse environments. This thesis focuses on the morphology of the endocranium, auditory bulla and cochlea in three tribes (Otomyini, Taterillini and Gerbillini) representing 10 species of African rodents, concentrating on their variability, function and adaptability, using micro-CT imaging and 3D shape comparative methods. Additionally, variations in cranial size were also studied in respective of global warming and climatic variables. Morphological changes/variations are a result of environmental change, therefore each chapter in this study details the effect of environmental change (in space and time) on different morphological traits i.e. general cranial size (chapter 2), cochlea and auditory bulla (chapter 3) and endocranial size and shape (chapter 4). With chapter 2 dealing specifically with climate change in its straict sense and the remaining two chapters looking at different environmental gradients. Chapter 2 tests the applicability of the "third universal response to warming" (i.e. declining body size) and the Resource Rule in two murid subfamilies, Murinae and Gerbillinae. The study shows that the third response is not as universal as only one species conformed to this response. Further, food availability (Resource Rule) was shown to be the more important factor correlated with body size variations in rodent species than Bergmann's Rule. [...]

Tooth cusp radius of curvature (RoC) has been hypothesized to play an important role in food item breakdown, but has remained largely unstudied due to difficulties in measuring and modeling RoC in multicusped teeth. We tested these hypotheses using a parametric model of a four cusped, maxillary, bunodont molar in conjunction with finite element analysis. When our data failed to support existing hypotheses, we put forth and tested the Complex Cusp Hypothesis which states that, during brittle food items breakdown, an optimally shaped molar would be maximizing stresses in the food item while minimizing stresses in the enamel. After gaining support for this hypothesis, we tested the effects of relative food item size on optimal molar morphology and found that the optimal set of RoCs changed as relative food item size changed. However, all optimal morphologies were similar, having one dull cusp that produced high stresses in the food item and three cusps that acted to stabilize the food item. We then set out to measure tooth cusp RoC in several species of extant apes to determine if any of the predicted optimal morphologies existed in nature and whether tooth cusp RoC was correlated with diet. While the optimal morphologies were not found in apes, we did find that tooth cusp RoC was correlated with diet and folivores had duller cusps while frugivores had sharper cusps. We hypothesize that, because of wear patterns, tooth cusp RoC is not providing a mechanical advantage during food item breakdown but is instead causing the tooth to wear in a beneficial fashion. Next, we investigate two possible relationships between tooth cusp RoC and enamel thickness, as enamel thickness plays a significant role in the way a tooth wears, using CT scans from hundreds of unworn cusps. There was no relationship between the two variables, indicating that selection may be acting on both variables independently to create an optimally shaped tooth. Finally, we put forth a framework for testing the functional optimality in teeth that takes into account tooth strength, food item breakdown efficiency, and trapability (the ability to trap and stabilize a food item).

No description available.

No description available.

The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. During recent years, research about individual variation in diet and morphology has gained interest in adaptive radiations and ecological speciation. Such variation among individual niche use may have important conservation implications as well as ecological and evolutionary implications. However, up to date we know very little about the extension of this phenomenon in natural populations and the mechanisms behind it. The results in this thesis show that the extension of individual diet specialization is widely spread throughout the animal kingdom. The variation in diet is mainly correlated to morphological variation but not always. Furthermore, this variation in diet and morphology among individuals could be both genetically determined and environmentally induced and it mainly comes from trade-offs in foraging efficiency between different prey types. The results from a number of studies of perch also show that individual perch differ in morphology and diet depending on habitat, where littoral perch has a deeper body compared to pelagic perch. This difference in morphology corresponds to functional expectations and is related to foraging efficiency trade-offs between foraging in the littoral and pelagic zone of a lake. The variation in morphology in perch is mainly due to phenotypic plasticity but there are also small genetic differences between the littoral and pelagic perch. Two separate studies show that both predation and competition may be important mechanism for the variation in morphology and diet in perch. In conclusion, the results in this thesis show that individual variation in diet and habitat choice is a common phenomenon with lots of ecological and evolutionary implications. However, there are many mechanisms involved in this phenomenon on which we are just about to start learning more about, and only further research in this area will give us the full insight.

Thraciidae é uma das famílias de Anomalodesmata menos estudadas, dentre as quatorze que compõem a subclasse. Das cerca de trinta espécies atribuídas à família, apenas Trigonothracia jinxingae teve sua biologia e anatomia examinadas em detalhes; para outros Thraciidae, há pouca ou nenhuma informação morfológica, o que dificulta o entendimento das relações filogenéticas dentre os Anomalodesmata. Thracia meridionalis, única representante da família em águas antárticas, é aqui analisada sob o ponto de vista da anatomia, buscando iniciar o entendimento da biologia da espécie, bem como aprofundar os conhecimentos acerca do gênero Thracia e família Thraciidae, indispensáveis para a elucidação das relações evolutivas dentre os Anomalodesmata. A investigação detalhada da concha, sifões, e das estruturas e órgãos que compõem a cavidade palial e massa visceral foi realizada utilizando-se técnicas de dissecção, histologia e microscopia eletrônica de varredura. A concha é fina, inequivalve, ornamentada por grânulos periostracais calcificados, e dotada de charneira edêntula, ligamento secundário e primário, este último com litodesma presente apenas em indivíduos jovens. O manto tem margens extensivamente fundidas, com curta abertura pediosa, quarta abertura palial reduzida e sifões longos, separados, originando-se exclusivamente das pregas internas; as glândulas hipobranquiais são assimétricas, porém restritas à câmara infra-branquial, o que distingue T. meridionalis dentre os Anomalodesmata. Os ctenídios são extensos, heterorrábdicos e do tipo E de Atkins; uma ampla abertura entre os eixos dos ctenídios e o septo que separa as aberturas proximais dos sifões permite a comunicação entre as câmaras infra e supra-branquiais. A associação entre os palpos labiais e ctenídios pertence à categoria III de Stasek, e os estatocistos são do tipo B3 de Morton, este tipo constituindo novo registro para os Thracioidea. O estômago do tipo IV na classificação de Purchon é extensivamente provido de áreas de triagem, sugerindo que o animal ingere grande quantidade de partículas, o que é corroborado pelo intestino freqüentemente dilatado e repleto de fezes. T. meridionalis é hermafrodita simultâneo, com gônadas, gonodutos e gonóporos distintos. Grandes ovócitos (~200 µm) protegidos por espessa membrana vitelínica, e razão próxima de 0,75 entre os comprimentos das prodissoconchas I e II são indicativos de desenvolvimento larval lecitotrófico. / The functional morphology of the Thraciidae is sparsely understood. Though several of its members had some morphological aspect described, only Trigonothracia jinxingae from Chinese waters is known in details, Thracia meridionalis being the first austral thraciid to be comprehensively reported upon. The latter species is the only representative of the family in Antarctic waters, and a common mud-dweller in the Admiralty Bay, King George Island, where living specimens were collected for the present study. T. meridionalis shares with Trigonothracia jinxingae many features that are typical of most Anomalodesmata: a secondary ligament of fused periostracum; extensively fused mantle margins; ctenidia of type E; ctenidial-labial palp junction of category III; stomach of type IV and simultaneous hermaphroditism. However, T. meridionalis is strikingly different from Trigonothracia in a number of aspects, as the presence of a fourth pallial aperture; statocysts of type B3; heterorhabdic ctenidia; a direct communication between the mantle chambers; deep-burrowing habit, the specimens lying on the left shell valve; siphons often retracted away from the sediment surface, protected within their mucous-lined burrows; stomach with extensive sorting areas; suspension-feeding habit; rectum passing over the kidneys and separate male and female gonadial apertures, thus revealing a greater diversity of form within the Thraciidae than is currently known.

Le taxon du Pléistocène inférieur Paranthropus robustus, dont l'holotype est le spécimen TM 1517, a été défini en 1938 par le paléontologue R. Broom suite à la découverte d'éléments crâniens et postcrâniens sur le site de Kromdraai, Gauteng, en Afrique du Sud. Depuis, d'autres sites sud-africains ont contribué à l'extension de son hypodigme et fourni la preuve de sa contemporanéité à l'échelle macro-régionale avec des représentants des taxons Australopithecus et Homo. L'identification des hominines étant principalement basée sur l'analyse de la variation morphologique des éléments cranio-dentaires, un enjeu majeur dans l'étude des assemblages fossiles des sites sud-africains concerne donc l'identification et l'attribution taxinomique de restes isolés et/ou fragmentaires du squelette axial et appendiculaire non associés à des éléments cranio-dentaires. Il en résulte que plusieurs aspects fonctionnels et paléobiologiques du squelette postcrânien de P. robustus restent à préciser. Au moyen de la microtomographie à rayons X, de l'imagerie virtuelle et d'analyses quantitatives en deux-trois dimensions, nous avons entrepris un projet de recherche visant à explorer, extraire et les patrons d'organisation endostructurale de spécimens fossiles communément, ou préliminairement, attribués à P. robustus. Sur une base comparative, nous visons à (i) identifier quelques caractéristiques osseuses endostructurales propres à ce taxon, qui pourraient fournir un cadre de référence pour l'attribution de spécimens fossiles isolés; (ii) déconstruire l'environnement biomécanique ayant façonné l'arrangement de l'os cortical et trabéculaire au niveau des articulations du coude, de la hanche et du genou; (iii) évaluer le degré de variation et, dans la mesure du possible, les différences liées au sexe et à l'âge. L'échantillon étudié comprend quatre huméri distaux (TM 1517g, SK 24600, SKX 10924, SKX 34805), cinq fémurs proximaux (SK 82, SK 97, SK 3121, SKW 19, SWT1/LB-2), une patella (SKX 1084), des éléments additionnels échantillonnant l'assemblage TM 1517 (l'ulna proximale TM 1517e, la phalange distale d'hallux TM 1517k) et deux ilia (TM 1605, SK 50) provenant des sites de Kromdraai et Swartkrans. [...] / The Early Pleistocene taxon Paranthropus robustus, represented by the holotype TM 1517, was established in 1938 by the paleontologist R. Broom following the discovery of craniodental and postcranial remains at the cave site of Kromdraai, in Gauteng, South Africa. Since, other Southern African sites have contributed to the extension of its hypodigm, providing evidence for its chronological overlap in the macro-region with representatives of the taxa Australopithecus and Homo. As species identification in the hominin fossil record is commonly based on the comparative assessment of craniodental anatomy and morphological variation, the rarity in the hominin-bearing South African cave assemblages of unambiguously associated craniodental and postcranial remains usually complicates the task of identifying isolated and fragmentary elements from the axial and the appendicular skeleton. Consequently, different functionally- and paleobiologically-related aspects of the P. robustus postcranial skeleton remain poorly known. By means of techniques of high resolution X-ray micro-tomography and virtual imaging coupled with two-three-dimensional quantitative analyses, in this research project we explored, extracted and assessed the patterns of endostructural organisation in some fossil specimens commonly, or tentatively, attributed to P. robustus. On comparative ground, we aim at (i) identifying some endostructural bony features characteristic of this taxon, if any, thus tentatively providing a reference framework for the attribution of isolated fossil specimens; (ii) deconstructing the biomechanical (loading) environment having shaped the cortical and cancellous bone arrangement at the elbow, the hip, and the knee joints; (iii) assessing variation and, whenever possible, sex- and age-related differences. The investigated sample consists of four distal humeri (TM 1517g, SK 24600, SKX 10924, SKX 34805), five proximal femora (SK 82, SK 97, SK 3121, SKW 19, SWT1/LB-2), a patella (SKX 1084), some additional elements from the assemblage labelled TM 1517 (the proximal ulna TM 1517e, the distal hallucial phalanx TM 1517k), and two ilia (TM 1605, SK 50) from the sites of Kromdraai and Swartkrans. [...]

Depuis leur domestication, les équidés sont étroitement associés aux activités humaines et ont, au fil des siècles, été façonnés au gré d’exigences morphologiques, esthétiques, d’allure ou de performance. Cette sélection artificielle a fortement impacté leurs traits phénotypiques et fonctionnels, produisant le large panel des races actuelles. Les sources historiques ont abondamment décrit l’importance des équidés et la diversité de leurs usages dans les sociétés passées. Ceci interroge donc sur la potentielle existence de types morphologiques spécialisés à des périodes antérieures à l’émergence des races. Dans ce contexte, les os présentent un intérêt particulier en tant que reflet des caractéristiques morphologiques et fonctionnelles des animaux du passé. En outre, les équidés étant fréquemment retrouvés sous la forme de squelettes complets en contexte archéologique,leurs restes offrent la possibilité d’étudier l’intégralité de la morphologie squelettique et notamment les interactions entre les os. Pourtant, les restes osseux d’équidés restent relativement peu exploités, probablement en raison des limites inhérentes aux méthodes d’étude actuelles. L’objectif de ce travail est de mieux comprendre la diversité phénotypique et fonctionnelle des équidés domestiques par des approches en morphométriegéométrique. La question de leur identification spécifique est tout d’abord abordée via la recherche de critères discriminants, qualitatifs et quantitatifs, applicables à du matériel archéologique. Les patterns de covariation entre les os sont ensuite explorés afin d’aborder des questions fonctionnelles. Les résultats révèlent une forte intégration morphologique entre les os des membres chez les équidés domestiques et mettent en évidence des différences entre les races selon un axe de covariation principalement porté par des interactions fonctionnelles. Ceci tend à montrer que la sélection artificielle, considérée comme le principal acteur de la diversification morphologique chez le cheval domestique, n’influence pas seulement le phénotype mais aussi les facteurs biologiques qui le sous-tendent. Enfin, une première application à des spécimens archéologiques permet dediscuter l’impact de potentielles formes de sélection artificielle et de standardisation morphologique sur des chevaux anciens. Les résultats démontrent l’intérêt d’étudier non seulement les variations de forme des os, mais aussi leurs covariations, afin d’enrichir nos connaissances concernant les traits morphologiques et fonctionnels des animaux passés, ainsi que les pratiques d’élevage qui y sont associées. L’étude des covariations contribueégalement à accroitre notre compréhension des processus micro-évolutifs, tels que la sélection artificielle, et à travers cela, permet de mieux documenter la manière dont la diversité phénotypique est produite. / Equids and humans share a long history of interaction from the first domestication to the standardization of modern breeds. In order to suit human activities, they have been molded through selection for conformation, harmony, gaits, or performance. This artificial selection is known to have largely impacted morphological and functional traits, producing the large range of current breeds. Historical sources extensively described the widepanel of equid usage in different human civilizations, raising the issue of the potential existence of specialized morphological types in the past, prior to the emergence of modern breeds. In this respect, bones prove to be of particular interest, as an image of the phenotypic and functional characteristics of past animals. Moreover, horses being often found as complete skeletons in archaeological contexts, their remains allow for the study of the complete skeletal morphology, especially concerning the interactions between bones. However, equid bone remains are largely under-explored, probably due to the recurrent limitations inherent to existing study methods. The objective of this work is to describe and understand the phenotypic and functional diversity of domestic equids, using geometric morphometrics approaches. Identification issues are firstly addressed through the research of qualitative and quantitative discrimination criteria, applicable to archaeological samples. Next, morphological and functional questions are addressed, especially investigating bone shape covariation. The obtained results reveal strong morphological integration within equid limb bones and evidenced breed specific differences along a covariation axis largely produced by functional interactions between bones. They show thatartificial selection, regarded as responsible of most of the modern diversification of horse breeds, not only targets the phenotype but also impacts the biological factors which underlie it. Finally, a first application to archaeological skeletons allows to question the influence of potential artificial selection and morphological standardization on past horses. The results demonstrate the interest of not only exploring bone shape variation,but also covariation, to increase our knowledge about the morphological and functional traits of past equids and about the related breeding practices. The study of morphological integration may also contribute to enhance our understanding of micro-evolutionary processes, such as artificial selection on domestic taxa, and through that, gain insights into how phenotypic diversity is produced.

Thraciidae é uma das famílias de Anomalodesmata menos estudadas, dentre as quatorze que compõem a subclasse. Das cerca de trinta espécies atribuídas à família, apenas Trigonothracia jinxingae teve sua biologia e anatomia examinadas em detalhes; para outros Thraciidae, há pouca ou nenhuma informação morfológica, o que dificulta o entendimento das relações filogenéticas dentre os Anomalodesmata. Thracia meridionalis, única representante da família em águas antárticas, é aqui analisada sob o ponto de vista da anatomia, buscando iniciar o entendimento da biologia da espécie, bem como aprofundar os conhecimentos acerca do gênero Thracia e família Thraciidae, indispensáveis para a elucidação das relações evolutivas dentre os Anomalodesmata. A investigação detalhada da concha, sifões, e das estruturas e órgãos que compõem a cavidade palial e massa visceral foi realizada utilizando-se técnicas de dissecção, histologia e microscopia eletrônica de varredura. A concha é fina, inequivalve, ornamentada por grânulos periostracais calcificados, e dotada de charneira edêntula, ligamento secundário e primário, este último com litodesma presente apenas em indivíduos jovens. O manto tem margens extensivamente fundidas, com curta abertura pediosa, quarta abertura palial reduzida e sifões longos, separados, originando-se exclusivamente das pregas internas; as glândulas hipobranquiais são assimétricas, porém restritas à câmara infra-branquial, o que distingue T. meridionalis dentre os Anomalodesmata. Os ctenídios são extensos, heterorrábdicos e do tipo E de Atkins; uma ampla abertura entre os eixos dos ctenídios e o septo que separa as aberturas proximais dos sifões permite a comunicação entre as câmaras infra e supra-branquiais. A associação entre os palpos labiais e ctenídios pertence à categoria III de Stasek, e os estatocistos são do tipo B3 de Morton, este tipo constituindo novo registro para os Thracioidea. O estômago do tipo IV na classificação de Purchon é extensivamente provido de áreas de triagem, sugerindo que o animal ingere grande quantidade de partículas, o que é corroborado pelo intestino freqüentemente dilatado e repleto de fezes. T. meridionalis é hermafrodita simultâneo, com gônadas, gonodutos e gonóporos distintos. Grandes ovócitos (~200 µm) protegidos por espessa membrana vitelínica, e razão próxima de 0,75 entre os comprimentos das prodissoconchas I e II são indicativos de desenvolvimento larval lecitotrófico. / The functional morphology of the Thraciidae is sparsely understood. Though several of its members had some morphological aspect described, only Trigonothracia jinxingae from Chinese waters is known in details, Thracia meridionalis being the first austral thraciid to be comprehensively reported upon. The latter species is the only representative of the family in Antarctic waters, and a common mud-dweller in the Admiralty Bay, King George Island, where living specimens were collected for the present study. T. meridionalis shares with Trigonothracia jinxingae many features that are typical of most Anomalodesmata: a secondary ligament of fused periostracum; extensively fused mantle margins; ctenidia of type E; ctenidial-labial palp junction of category III; stomach of type IV and simultaneous hermaphroditism. However, T. meridionalis is strikingly different from Trigonothracia in a number of aspects, as the presence of a fourth pallial aperture; statocysts of type B3; heterorhabdic ctenidia; a direct communication between the mantle chambers; deep-burrowing habit, the specimens lying on the left shell valve; siphons often retracted away from the sediment surface, protected within their mucous-lined burrows; stomach with extensive sorting areas; suspension-feeding habit; rectum passing over the kidneys and separate male and female gonadial apertures, thus revealing a greater diversity of form within the Thraciidae than is currently known.

Les Gastornithidae sont des oiseaux géants terrestres présents dans le Tertiaire (Paléocène- Eocène) d'Europe, d'Amérique du Nord et d'Asie. Bien que ces oiseaux soient connus depuis le 19ème siècle, leur écologie et les environnements dans lesquels ils vivaient sont encore très mal connus. Cette thèse propose donc d'apporter des réponses sur ces deux points afin de mieux comprendre ces oiseaux grâce à une approche pluridisciplinaire, combinant des études de morphologie-fonctionnelle, de géochimie isotopique, et de paléontologie. Nous avons pu déterminer que cet oiseau de deux mètres de haut devait peser entre 110 et 260 kg, et avait un déplacement relativement lent ne lui permettant pas de courir rapidement et longtemps. Le régime alimentaire des Gastornithidae, en débat depuis plus de vingt ans, a été ré-étudié grâce à une étude de géochimie isotopique combinée à une étude de morphologie fonctionnelle, permettant de conclure à une alimentation herbivore. Parallèlement, les paléo-environnements dans lesquels évoluaient cet oiseau ont également pu être étudiés grâce une étude de géochimie isotopique appliquée à des coquilles d'oeufs fossiles du Sud de la France attribuées à Gastornis dans cette thèse. Ces grands oiseaux vivaient donc dans un environnement relativement sec et chaud avec probablement une alternance de saison sèche et humide pour le Sud de la France, ce qui est différent de ce qu'on connait pour des environnements du centre de l'Allemagne où d'autres fossiles de Gastornis ont été trouvés, et où la végétation montre un environnement plus humide. Cela montre donc que cet oiseau avait une bonne capacité d'adaptation à différents environnements, ce qui lui a probablement permis de franchir le PETM sans être particulièrement affecté, comme le montre le registre fossile dans lequel aucune extinction, aucune variation géographique ou anatomique ne sont observées dans cette famille contrairement au cas de nombreux mammifères / Gastornithidae are a familly of large ground fossils birds present in the Tertiary (Paleocene- Eocene) from Europe, North America and Asia. Although these birds are known since the beginning of the 19th century, their ecology and the environment where they lived are still poorly known. Therefore, this PhD propose to bring some answers about this two points in order to better understand these birds using a multidisciplinary approach, including functional morphology, isotope geochemistry and paleontological studies. We have determined that this two meter high bird should weigh around 110 to 260 kg, and had a relatively slow locomotion not allowing him to run quickly and for a long time. The diet of the Gastornithidae, discussed since more twenty years, has been studied using an isotopic geochemical approach combine with a morphofunctional study, which permits to conclude to an herbivore diet. In parallel, paleo-environments where lived this bird have also been studied using isotopical analysis applied on fossils bird’s eggshells from the southern France, attributed to Gastornis in this thesis. Thus these large birds lived in an environment relatively dry and hot, with probably an alternance of dry and wet saison in the southern France, which is different than which is known in middle Germany environments where other Gastornis fossils were found, and where vegetation shows an environment wetter. Therefore, that shows that this bird had a good adaptability to different environments, which allowed him to cross the PETM without being particularly affected as shown in the fossil record, on the contrary to numerous mammals