Spelling suggestions: "subject:"geometric morphometric"" "subject:"geometric imorphometric""
1 |
A quantitative assessment of infraorbital morphology in Homo: testing for character independence and evolutionary significance in the human midfaceMaddux, Scott David 01 January 2011 (has links)
Features of the infraorbital region, such as infraorbital surface topography, infraorbital surface orientation, and curvature of the zygomaticoalveolar crest, have long played a prominent role in phylogenetic analyses of Homo. However, there is currently considerable debate regarding the phylogenetic reliability of infraorbital characters, as numerous researchers have questioned the degree to which these features are morphologically independent of one another and facial size. These questions largely stem from methodological limitations for accurately quantifying the curvilinear morphology of the infraorbital surface and zygomaticoalveolar crest, which have significantly impeded the ability to discern patterns of infraorbital integration and allometry. In this study, infraorbital surface and zygomaticoalveolar crest morphology are precisely assessed, through geometric morphometric methodologies well-suited for quantifying complex curvilinear structures, in a large sample of fossil (n = 71) and recent Homo (n = 303). Once quantified, measures of infraorbital surface topography, infraorbital surface orientation and zygomaticoalveolar crest curvature are further evaluated for intercorrelation and allometry in order to more fully evaluate the morphological independence of commonly cited infraorbital characters. The results of this study indicate that most aspects of infraorbital surface topography, infraorbital surface orientation and zygomaticoalveolar crest curvature are significantly correlated with facial size across Homo. Moreover, certain aspects of infraorbital shape, such the degree of infraorbital surface depression and the overall curvature of the zygomaticoalveolar crest, appear to show additional, size-independent, intercorrelations, suggesting they form a singular "infraorbital complex." In light of these results, the use of infraorbital characters as separate independent characters in phylogenetic assessments of Homo is called into question, while the importance of facial size in human craniofacial evolution is further highlighted.
|
2 |
Analysis of sexual dimorphism in human eye orbits using computed tomographyLidstone, Laura J. 09 September 2011 (has links)
A plethora of anthropological studies have been undertaken on the skull, including many analyses of sexual dimorphism. Sexual dimorphism reflected in the eye orbits has not always demonstrated consistent or reliable results. However, recent studies (Pretorius, Steyn, & Scholtz, 2006; Ji et al., 2010) suggest some positive results utilizing geometric morphometrics to predict sex. Utilizing 97 post-mortem CT (computed tomography) scans, established morphological and metric techniques for sex determination were assessed from 3D rendered models of the crania. In addition, landmark data were collected on the orbital margin to evaluate the accuracy of sex determination using geometric morphometric techniques. Traditional methods demonstrated poor levels of accuracy for prediction of sex, however, utilizing generalised procrustes analysis and discriminant function analysis on 3D landmark data resulted in 94.95% overall accuracy. Application of recent methodological advances, including geometric morphometrics, should continue to be developed as it increases the ability to assess sexual dimorphism which will allow for greater identification of unknown remains.
|
3 |
Analysis of sexual dimorphism in human eye orbits using computed tomographyLidstone, Laura J. 09 September 2011 (has links)
A plethora of anthropological studies have been undertaken on the skull, including many analyses of sexual dimorphism. Sexual dimorphism reflected in the eye orbits has not always demonstrated consistent or reliable results. However, recent studies (Pretorius, Steyn, & Scholtz, 2006; Ji et al., 2010) suggest some positive results utilizing geometric morphometrics to predict sex. Utilizing 97 post-mortem CT (computed tomography) scans, established morphological and metric techniques for sex determination were assessed from 3D rendered models of the crania. In addition, landmark data were collected on the orbital margin to evaluate the accuracy of sex determination using geometric morphometric techniques. Traditional methods demonstrated poor levels of accuracy for prediction of sex, however, utilizing generalised procrustes analysis and discriminant function analysis on 3D landmark data resulted in 94.95% overall accuracy. Application of recent methodological advances, including geometric morphometrics, should continue to be developed as it increases the ability to assess sexual dimorphism which will allow for greater identification of unknown remains.
|
4 |
Estruturação populacional, variações fenotípicas e estudos morfométricos em Apis mellifera (Hymenoptera: Apidae) no Brasil / Populational structuration, phenotypic variations and morphometric studies in Apis mellifera (Hymenoptera: Apidae) in Brazil.Nunes, Lorena Andrade 07 March 2012 (has links)
Apis mellifera é uma espécie de abelha bastante estudada sob diferentes perspectivas, tanto em pesquisas básicas como aplicadas. Possui uma natureza singular associada não só a interesses econômicos como produção de cera, mel, própolis, geléia real, pólen, mas também, por seu potencial agrícola como polinizador. Esta espécie tem sido alvo de muitos estudos morfométricos, principalmente pela sua importância ecológica, pela sua grande capacidade de adaptação, sua ampla distribuição e por serem capazes de se estabelecer eficientemente em diversos ambientes. A morfometria geométrica permite uma análise rigorosa da variação da forma de uma determinada estrutura em organismos de diversos tamanhos, principalmente utilizando métodos de estatística multivariada, além de ser capaz de avaliar a instabilidade no desenvolvimento de um organismo. O presente trabalho teve como objetivo estudar as variações da forma e tamanho em asas e corbículas de operárias de Apis mellifera, provenientes das 5 regiões geográficas do Brasil, utilizando análises morfogeométricas. A existência de padrões de variação de forma e tamanho das abelhas africanizadas no Brasil obtidos há 16 anos em estudo clássico realizado por Diniz-Filho e Malaspina, possibilitou uma análise espaço-temporal comparativa com os resultados obtidos utilizando recursos tecnológicos atuais para a avaliação de dados morfométricos, bem como, verificar por meio das análises de assimetria flutuante a plasticidade fenotípica no tamanho e forma da asa e corbícula dessa espécie, possibilitou ainda, avaliar se condições adversas relacionadas às ações antrópicas influenciam no aumento de desvios na simetria bilateral desses caracteres morfológicos. Foi realizada uma amostragem abrangendo as 5 regiões geográficas do Brasil, pela forma das asa e análises multivariadas verificou-se que existe um padrão geográfico entre as populações de Apis mellifera no Brasil (P < 0,001). Essas variações geográficas podem ser devidas à grande extensão territorial, além da possível associação das diferenças entre ecorregiões. Verificou-se, também, a presença de assimetria flutuante na forma das asas e das corbículas de Apis mellifera em todas as populações estudadas, porém, na análise multivariada e assimetria do tamanho não obteve significância em algumas populações, constatando-se que para estudo de assimetria e distribuição populacional a forma da asa e das corbículas é a análise mais indicada e que apresenta maior precisão. / Apis mellifera is bee specie very studied under different perspectives, as for basic studies to applied ones. They have a singular nature, not only associated to economic issues as wax, honey, propolis, royal jelly and pollen production, but also for their agricultural potential as pollinators. This specie has been long aimed for morphometric studies, because of its ecological importance, easy capacity of adaptation, large distribution and for being able of efficient establishment in diverse environments. The geometric morphometric allows rigorous analyses in shape variation of a given structure in organism of diverse sizes, especially when using multivariate statistics methods, enabling the evaluation of instability in the development of an organism. The present study aim the variations of shape and size in wings and pollen basket from workers of Apis mellifera, acquired at 5 geographic regions of Brazil, using morphogeometric analyses. The existence of variation patters in shape and size of Africanized bees in Brazil, obtained 16 years ago in classic study made by Diniz-Filho and Malaspina, made possible a comparative spatialtemporal analyses with the results obtained in this study, using updated technology resources for evaluation of morphometric data, as well as the phenotypic plasticity exam of size and shape in wings and pollen basket of this specie, using fluctuating asymmetric analysis, and evaluate if diverse conditions made by anthropomorphic actions has influence on the deviation increase among bilateral symmetry of this morphological characters. The sample was made including 5 geographic regions of Brazil. By the wings size shape and multivariate analyses, it was verified the existence of a geographic pattern among Brazilian Apis mellifera populations (P< 0,001). Those geographical variations may be caused due to the big territorial expansion, alongside with the possible association of different ecoregions. It was also verified floating asymmetric in the shape of wings and pollen basket from Apis mellifera in all studied populations, however, in the multivariate analyses the asymmetry in shape was not significant in some populations, showing that, for studies of asymmetry and populational distribution, the shape of wings and pollen basket is the most indicated and precise analyses.
|
5 |
Evolução morfológica de Ceratosauria e Tyrannosauroidea (Dinosauria: Theropoda) / Morphological Evolution in Ceratosauria e Tyrannosauroidea (Dinosauria: Theropoda)Ferreira, Rafael Delcourt de Seixas 08 July 2016 (has links)
Theropoda foram os dinossauros mais bem sucedidos durante e Era Mesozoica e mantiveram-se bem diversos até os tempos presentes. Dentre eles, Tyrannosauroidea e Ceratosauria foram amplamente distribuídos entre os hemisférios norte e sul durante os Períodos Jurássico e Cretáceo, respectivamente. Ambos foram predadores de topo, com formas basais possuindo crânios pequenos, pescoços compridos, pernas e caudas alongadas; enquanto as formas mais derivadas eram caracterizadas com crânios maiores, pescoços curtos e membros anteriores e caudas reduzidas. Apesar de Tyrannosauroidea não ser próximo filogeneticamente de Ceratosauria, esse padrão evolutivo é encontrado em ambas as linhagens. Na presente tese a evolução de ambos os clados é testada utilizando morfometria geométrica nos elementos cranianos, além de medidas lineares e descrições qualitativas. Foram visitadas no total 17 coleções paleontológicas distribuídas no Brasil, Argentina, EUA, Mongólia e China a fim de coletar dados sobre terópodes. Os espécimes examinados foram fotografados, medidos e descritos. Os dados morfométricos foram tratados utilizando os softawares da série TPS e MorphoJ resultando em 54 landmarks nos caracteres cranianos. A fim de avaliar a relação entre os crânios e os landmarks, foram excluídos alguns landmarks do conjunto de dados original. Todos os conjuntos de dados resultantes mostraram poucas variações no morfoespaço, independente do número de landmarks. Foi concluído que a parte anterior do crânio desenvolve-se independentemente da região posterior, após a fenestra anterorbital, em ambos os clados. Ceratosauria é o clado com maior disparidade entre os terópodes carnívoros, especialmente Carnotaurus sastrei. Tyrannosauroidea apresentaram crânios mais conservativos. A disparidade morfológica está relacionada à antiguidade das linhagens e ampla distribuição geográfica. A análise de regressão linear demonstrou que Tyrannosaurus rex pode apresentar grande amplitude fenotípica durante o desenvolvimento ontogenético, e sugere que Nanotyrannus e Raptorex sejam sinônimos juniores de Tyrannosaurus e Tarbosaurus baatar respectivamente. O desenvolvimento ontogenético de Ceratosauria é difícil de avaliar, no entanto Limusaurus inextricabilis apresenta diversas mudanças cranianas durante a fase de crescimento, sugerindo perda de todos os dentes, migração posterior da fenestra pró-maxilar, aumento da órbita e rostro. Ceratosauria e Tyrannosauroidea aumentam de tamanho durante o desenvolvimento filogenético, mas apesar da estrutura corporal ser semelhante, não há convergência morfológica e funcional entre os dois clados. A única convergência entre Tyrannosauroidea e Ceratosauria parece ser ecológica. Tyrannosauridae gráceis como Gorgosaurus libratus, Alioramus altai e juvenis de Tyrannosaurus poderiam ter funções ecológicas semelhantes à Abelisauridae. Por outro lado, Tyrannosauridae mais robustos como Tyrannosaurus, Tarbosaurus e Daspletosaurus torosus poderiam xi ter um nicho mais amplo. Acerca da distribuição e funções ecológicas de Abelisauridae, esse clado poderia ter empurrado Carcharodontosauridae para a extinção, uma vez que ambos apresentam similares convergências craniodentárias e mecânicas. / Theropods were the most successful dinosaurs during the Mesozoic Era, being still well diversied until recent times through the clade Aves. Among them, Tyrannosauroidea and Ceratosauria had a wide distribution, being commonly found on the Northern and Southern Hemispheres, respectively, in the Jurassic and Cretaceous Periods. Both were top predators, known in its basal form, to have small heads, long necks, long forelimbs and tails, whereas the most derived forms were characterized by a large head, short neck, short forelimb and tail. Although Tyrannosauroidea is not phylogenetically close to Ceratosauria, a similar developmental pattern is found in both lineages. In the present thesis, I assessed the evolutionary pattern of morphological shape in both clades using landmark-based geometric morphometric techniques on their skulls, along with some linear measurement and qualitative descriptions. Seventeen paleontological collections distributed in Brazil, Argentina, USA, Mongolia, and China were visited to collect data on these theropods. Specimens examined were photographed, measured and described. The morphometric data were treated using the software TPS series and MorphoJ resulting in 54 landmarks on skull characters. To assess different relationships among the landmarks and the skulls I excluded some landmarks in the original dataset. All datasets show few variations in morphospace, independent of the number of landmarks. Here, I conclude that the anterior part of the skull developed independently from the posterior part of the braincase (posterior to the antorbital fenestra) in both groups independently. Ceratosauria is the clade with more disparity among carnivorous theropods, especially when considering Carnotaurus sastrei. Tyrannosauroidea shows signs of having more conservative skulls. The development of morphological disparity is related to old lineages with long geographical distributions. The linear regression showed that Tyrannosaurus rex could have been more phenotypically spread during ontogenetic development, suggesting that Nanotyrannus and Raptorex are junior synonyms of Tyrannosaurus and Tarbosaurus baatar, respectively. Ontogenetic traits in Ceratosauria are difficult to assess, but Limusaurus inextricabilis showed high rates of change on its skull throughout its development, suggesting that they might loose all teeth, and have xii posterior migration of the promaxillary fenestra, increasing the orbit and snout during the ontogenetic development. Ceratosauria and Tyrannosauroidea show a tendency to larger and heaver forms from basal to more derived forms in their phyogeny. Although main body plan is similar in both group, there are neither morphological nor functional convergences between Ceratosauria and Tyrannosauroidea. The only observed convergence between Tyrannosauridae and Ceratosauria appears to be ecological. Gracile Tyrannosauridae such as Gorgosaurus libratus, Alioramus altai and juvenile Tyrannosaurus may have had similar ecological roles with Abelisauridae. On the other hand, Tyrannosauridae such as Tyrannosaurus, Tarbosaurus and Daspletosaurus torosus may have had a broader niche. Concerning distribution and ecological functions of Abelisauridae, this clade may have pushed another southern clade, the Carcharodontosauridae, to extinction since both clades had similar craniodental and mechanical skull morphologies.
|
6 |
Candidate gene analyses of craniofacial variation in malocclusion phenotypesSouza Gomes da Fontoura, Clarissa 01 May 2019 (has links)
The precise role that genes play in early craniofacial development and postnatal craniofacial growth are essential to understand dento-facial development overall. However, genotype-phenotype correlations between genetic variation of early craniofacial genes and adult craniofacial phenotypes is poorly understood. Thus, this thesis focused on identifying the genetic etiology underlying phenotypic variations present in malocclusion conditions. First, we performed genotype-phenotype association analyses between common variants in 82 craniofacial genes and phenotypic variations extracted from 2D and 3D pre-treatment dental records of individuals with malocclusion. This effort identified that variant rs2189000 upstream of TWIST1 is highly associated with mandibular body length and inclination and cranial base angulations which can lead to malocclusion. Next, via cell based functional assays, we discovered that rs2189000 disrupts a PITX2 binding site and also showed the direct regulation of TWIST1 expression by the PITX2 gene. Finally, we identified abnormal craniofacial phenotypes and malocclusion in Twist1 deleted mice including asymmetric snouts, domed cranial vaults, and changes in size and inclination of the cranial base, palate and mandible resulting in malocclusion and resembling the human phenotypes observed. Also, premature calcification of calvarial sutures and cranial base synchondroses were also observed in the mutant mice indicating a possible biological mechanism for the abnormal phenotypes detected. These results confirm that TWIST1 is an important regulator of postnatal growth and that genetic variation in TWIST1 can result in malocclusion. The continued identification of genetic etiological factors and their role in craniofacial growth will impact treatment and prevention of malocclusion and other craniofacial conditions
|
7 |
Etude de la variabilité en fonction du sexe, de l'âge et de l'origine géographique de l'extrémité distale du fémur / Study of the sex, age and geography based variability in the distal femurCavaignac, Étienne 10 November 2017 (has links)
La morphologie des os humains varie en fonction du sexe, de l'âge et de l'ethnie. Cette variabilité de l'anatomie humaine peut aider à déterminer le sexe, l'âge et l'ethnie. Les outils utilisés pour de telles analyses sont classiquement des méthodes ostéométriques (longueur, angle, rapport de longueur) qui peuvent être sujettes à des biais d'analyse ou d'interprétation. L'analyse morphométrique géométrique 3D (MG) permet de limiter ces biais. Elle étudie et compare la forme d'un ou plusieurs objets en éliminant les effets liés à la taille de celui-ci. Nous n'avons pas retrouvé d'analyse du dimorphisme sexuel, ethnique et lié à l'âge de l'extrémité distale du fémur à l'aide de cette méthode. Le fémur est pourtant un des plus gros os du corps et il est souvent bien conservé dans les restes humains. L'objectif de ce travail était de montrer qu'il existe une différence de forme du fémur distal en fonction de l'âge, du sexe et de l'ethnie visualisable grâce à MG. Nous avons réalisé une MG de 482 scanners d'extrémité distale de fémur de sujets vivant dans le sud de la France et dans la région de Chongqing (chine). Les sujets présentant une pathologie osseuse ou articulaires ont été exclus. Dix landmarks ont été positionnés sur des reconstructions tridimentionelles. Nous avons également réalisé une analyse ostéométrique " classique " en plus de MG afin d'évaluer la vraisemblance de nos résultats. Les données ont été analysées par deux observateurs à deux temps différents. Nous avons calculé pour chaque landmark la variabilité inter et intraobservateur. Les landmarks choisis permettaient de caractériser la forme de l'extrémité distale du fémur. La première étape a consisté en la réalisation d'une analyse généralisée procrustre (GPA). Les coordonnées dans l'espace des landmarks ont été analysées en utilisant une analyse en composant principal (PCA). Une analyse discriminante a permis de vérifier le pourcentage de cas dans lequel le sexe, l'âge ou l'ethnie estimés étaient les bons. GPA retrouve une différence de forme statistiquement significative entre les sexes, en fonction de l'âge et entre les ethnies. PCA retrouve une différence de forme en fonction de l'âge, du sexe ou de l'ethnie qui représente respectivement 54,4 ;58,6 et 61,9% de la variabilité observée. Les taux d'assignement correct avec cette méthode étaient de 80% (âge) ; 77,3% (sexe) et 82 % (l'ethnie). L'analyse ostéométrique " classique " retrouvait des valeurs comparables à celles retrouvées dans la littérature. Le pourcentage d'erreur intra et inter observateur pour l'ensemble des landmarks n'excédait jamais 2%. Nous avons démontré que l'analyse MG du fémur distal permettait de mettre en évidence une variabilité en fonction du sexe, de l'âge et de l'ethnie de ce segment osseux. La reproductibilité élevée et la vraisemblance des résultats valident notre méthodologie. Cette différence de forme a des retombées directes en anthropobiologie mais aussi en orthopédie. Cette méthode d'assignation ne donne pas de résultats suffisamment précis pour être utilisée seule. Cependant, elle a l'avantage de pouvoir être utilisée dans des contextes d'autopsie virtuelle ou in vivo. Par ailleurs, par la présente étude nous réactualisons les données morphométriques de population contemporaine du sud de la France et aussi de la région de Chongqing en chine. Cette méthodologie adéquate et reproductible va permettre de réaliser des comparaisons diachroniques ainsi qu'inter ethnique. La validation de l'utilisation d'examen d'imagerie médicaux ouvre un champ nouveau en anthropologie physique. En ce qui concerne l'aspect orthopédique, cette variabilité questionne sur la nécessité ou non d'implant spécifique et surtout sur la nécessité de réévaluer de manière régulière la forme des prothèses de genou. / The shape of human bones varies based on age, sex and ethnicity. This variability in human anatomy can be used to determine a person's age, sex and ethnicity. Historically, the tools used for such analyses are osteometric methods (length, angle, length ratio) that can be plagued by analysis or interpretation biases. Three-dimensional geometric morphometric analysis (3D GM) can limit the impact of these biases. It is used to describe and compare the general shape of one or more objects by eliminating any size-related effects. To the best of our knowledge, this method has never been used to analyse the sexual dimorphism, ethnicity-related and age-related differences in the distal femur. The femur is one of the longest human bones and is often well preserved in human remains. The goal of this study was to demonstrate differences in the shape of the distal femur according to age, sex and ethnicity using GM. We carried out 3D GM on 482 CT scans of the distal femur of adults living in the South of France and in the Chongqing region of China. Subjects with bone or joint pathologies were excluded. Ten landmarks were defined on 3D reconstructions of the distal femur. A standard osteometric analysis was performed in addition to the GM analysis to evaluate the plausibility of our results. The data were analysed by two observers at two different times. This allowed us to calculate the inter- and intra-observer variability for each landmark. The chosen landmarks were used to characterise the shape of the distal femur. The first step consisted of a generalized Procrustes analysis (GPA). The landmarks' coordinates in space were analysed using a principal component analysis (PCA). A discriminant analysis was performed to determine the percentage of cases in which the sex, age or ethnicity was correctly estimated. The GPA found a statistically significant difference in the distal femur shape between different sexes, ethnicity groups and age groups. The PCA found that age, sex and ethnicity accounted for 54.4%, 58.6% and 61.9% of the observed variability in distal femur shape, respectively. Using this method, 80% of cases were assigned the correct age, 77.3% the correct sex and 82% the correct ethnic group. The results of the osteometric analysis were comparable to published values. The percentage error for the intra- and interobserver comparisons for all the landmarks was always less than 2%. In this study, MG analysis of the distal femur revealed age-related, sex-related and ethnicity-related variability in the distal femur. The high reproducibility and plausibility of our results validate our methodology. These shape differences have direct implications for anthropobiology and also orthopaedics. Although this method is not sufficiently accurate to be used alone, it has the advantage of being usable in the context of virtual or in vivo autopsy cases. Moreover, this study has updated the morphometric data for a modern population in the south of France and the Chongqing region of China. This reliable and accurate methodology can be used to perform diachronic and interethnic comparisons. Validation of this medical imaging modality opens new avenues in physical anthropology research. In the orthopaedics field, this variability means that the shape of implants used for knee arthroplasty should be re-assessed regularly and brings into question the need for gender-specific or ethnicity-specific implants.
|
8 |
Evolução morfológica de Ceratosauria e Tyrannosauroidea (Dinosauria: Theropoda) / Morphological Evolution in Ceratosauria e Tyrannosauroidea (Dinosauria: Theropoda)Rafael Delcourt de Seixas Ferreira 08 July 2016 (has links)
Theropoda foram os dinossauros mais bem sucedidos durante e Era Mesozoica e mantiveram-se bem diversos até os tempos presentes. Dentre eles, Tyrannosauroidea e Ceratosauria foram amplamente distribuídos entre os hemisférios norte e sul durante os Períodos Jurássico e Cretáceo, respectivamente. Ambos foram predadores de topo, com formas basais possuindo crânios pequenos, pescoços compridos, pernas e caudas alongadas; enquanto as formas mais derivadas eram caracterizadas com crânios maiores, pescoços curtos e membros anteriores e caudas reduzidas. Apesar de Tyrannosauroidea não ser próximo filogeneticamente de Ceratosauria, esse padrão evolutivo é encontrado em ambas as linhagens. Na presente tese a evolução de ambos os clados é testada utilizando morfometria geométrica nos elementos cranianos, além de medidas lineares e descrições qualitativas. Foram visitadas no total 17 coleções paleontológicas distribuídas no Brasil, Argentina, EUA, Mongólia e China a fim de coletar dados sobre terópodes. Os espécimes examinados foram fotografados, medidos e descritos. Os dados morfométricos foram tratados utilizando os softawares da série TPS e MorphoJ resultando em 54 landmarks nos caracteres cranianos. A fim de avaliar a relação entre os crânios e os landmarks, foram excluídos alguns landmarks do conjunto de dados original. Todos os conjuntos de dados resultantes mostraram poucas variações no morfoespaço, independente do número de landmarks. Foi concluído que a parte anterior do crânio desenvolve-se independentemente da região posterior, após a fenestra anterorbital, em ambos os clados. Ceratosauria é o clado com maior disparidade entre os terópodes carnívoros, especialmente Carnotaurus sastrei. Tyrannosauroidea apresentaram crânios mais conservativos. A disparidade morfológica está relacionada à antiguidade das linhagens e ampla distribuição geográfica. A análise de regressão linear demonstrou que Tyrannosaurus rex pode apresentar grande amplitude fenotípica durante o desenvolvimento ontogenético, e sugere que Nanotyrannus e Raptorex sejam sinônimos juniores de Tyrannosaurus e Tarbosaurus baatar respectivamente. O desenvolvimento ontogenético de Ceratosauria é difícil de avaliar, no entanto Limusaurus inextricabilis apresenta diversas mudanças cranianas durante a fase de crescimento, sugerindo perda de todos os dentes, migração posterior da fenestra pró-maxilar, aumento da órbita e rostro. Ceratosauria e Tyrannosauroidea aumentam de tamanho durante o desenvolvimento filogenético, mas apesar da estrutura corporal ser semelhante, não há convergência morfológica e funcional entre os dois clados. A única convergência entre Tyrannosauroidea e Ceratosauria parece ser ecológica. Tyrannosauridae gráceis como Gorgosaurus libratus, Alioramus altai e juvenis de Tyrannosaurus poderiam ter funções ecológicas semelhantes à Abelisauridae. Por outro lado, Tyrannosauridae mais robustos como Tyrannosaurus, Tarbosaurus e Daspletosaurus torosus poderiam xi ter um nicho mais amplo. Acerca da distribuição e funções ecológicas de Abelisauridae, esse clado poderia ter empurrado Carcharodontosauridae para a extinção, uma vez que ambos apresentam similares convergências craniodentárias e mecânicas. / Theropods were the most successful dinosaurs during the Mesozoic Era, being still well diversied until recent times through the clade Aves. Among them, Tyrannosauroidea and Ceratosauria had a wide distribution, being commonly found on the Northern and Southern Hemispheres, respectively, in the Jurassic and Cretaceous Periods. Both were top predators, known in its basal form, to have small heads, long necks, long forelimbs and tails, whereas the most derived forms were characterized by a large head, short neck, short forelimb and tail. Although Tyrannosauroidea is not phylogenetically close to Ceratosauria, a similar developmental pattern is found in both lineages. In the present thesis, I assessed the evolutionary pattern of morphological shape in both clades using landmark-based geometric morphometric techniques on their skulls, along with some linear measurement and qualitative descriptions. Seventeen paleontological collections distributed in Brazil, Argentina, USA, Mongolia, and China were visited to collect data on these theropods. Specimens examined were photographed, measured and described. The morphometric data were treated using the software TPS series and MorphoJ resulting in 54 landmarks on skull characters. To assess different relationships among the landmarks and the skulls I excluded some landmarks in the original dataset. All datasets show few variations in morphospace, independent of the number of landmarks. Here, I conclude that the anterior part of the skull developed independently from the posterior part of the braincase (posterior to the antorbital fenestra) in both groups independently. Ceratosauria is the clade with more disparity among carnivorous theropods, especially when considering Carnotaurus sastrei. Tyrannosauroidea shows signs of having more conservative skulls. The development of morphological disparity is related to old lineages with long geographical distributions. The linear regression showed that Tyrannosaurus rex could have been more phenotypically spread during ontogenetic development, suggesting that Nanotyrannus and Raptorex are junior synonyms of Tyrannosaurus and Tarbosaurus baatar, respectively. Ontogenetic traits in Ceratosauria are difficult to assess, but Limusaurus inextricabilis showed high rates of change on its skull throughout its development, suggesting that they might loose all teeth, and have xii posterior migration of the promaxillary fenestra, increasing the orbit and snout during the ontogenetic development. Ceratosauria and Tyrannosauroidea show a tendency to larger and heaver forms from basal to more derived forms in their phyogeny. Although main body plan is similar in both group, there are neither morphological nor functional convergences between Ceratosauria and Tyrannosauroidea. The only observed convergence between Tyrannosauridae and Ceratosauria appears to be ecological. Gracile Tyrannosauridae such as Gorgosaurus libratus, Alioramus altai and juvenile Tyrannosaurus may have had similar ecological roles with Abelisauridae. On the other hand, Tyrannosauridae such as Tyrannosaurus, Tarbosaurus and Daspletosaurus torosus may have had a broader niche. Concerning distribution and ecological functions of Abelisauridae, this clade may have pushed another southern clade, the Carcharodontosauridae, to extinction since both clades had similar craniodental and mechanical skull morphologies.
|
9 |
Estruturação populacional, variações fenotípicas e estudos morfométricos em Apis mellifera (Hymenoptera: Apidae) no Brasil / Populational structuration, phenotypic variations and morphometric studies in Apis mellifera (Hymenoptera: Apidae) in Brazil.Lorena Andrade Nunes 07 March 2012 (has links)
Apis mellifera é uma espécie de abelha bastante estudada sob diferentes perspectivas, tanto em pesquisas básicas como aplicadas. Possui uma natureza singular associada não só a interesses econômicos como produção de cera, mel, própolis, geléia real, pólen, mas também, por seu potencial agrícola como polinizador. Esta espécie tem sido alvo de muitos estudos morfométricos, principalmente pela sua importância ecológica, pela sua grande capacidade de adaptação, sua ampla distribuição e por serem capazes de se estabelecer eficientemente em diversos ambientes. A morfometria geométrica permite uma análise rigorosa da variação da forma de uma determinada estrutura em organismos de diversos tamanhos, principalmente utilizando métodos de estatística multivariada, além de ser capaz de avaliar a instabilidade no desenvolvimento de um organismo. O presente trabalho teve como objetivo estudar as variações da forma e tamanho em asas e corbículas de operárias de Apis mellifera, provenientes das 5 regiões geográficas do Brasil, utilizando análises morfogeométricas. A existência de padrões de variação de forma e tamanho das abelhas africanizadas no Brasil obtidos há 16 anos em estudo clássico realizado por Diniz-Filho e Malaspina, possibilitou uma análise espaço-temporal comparativa com os resultados obtidos utilizando recursos tecnológicos atuais para a avaliação de dados morfométricos, bem como, verificar por meio das análises de assimetria flutuante a plasticidade fenotípica no tamanho e forma da asa e corbícula dessa espécie, possibilitou ainda, avaliar se condições adversas relacionadas às ações antrópicas influenciam no aumento de desvios na simetria bilateral desses caracteres morfológicos. Foi realizada uma amostragem abrangendo as 5 regiões geográficas do Brasil, pela forma das asa e análises multivariadas verificou-se que existe um padrão geográfico entre as populações de Apis mellifera no Brasil (P < 0,001). Essas variações geográficas podem ser devidas à grande extensão territorial, além da possível associação das diferenças entre ecorregiões. Verificou-se, também, a presença de assimetria flutuante na forma das asas e das corbículas de Apis mellifera em todas as populações estudadas, porém, na análise multivariada e assimetria do tamanho não obteve significância em algumas populações, constatando-se que para estudo de assimetria e distribuição populacional a forma da asa e das corbículas é a análise mais indicada e que apresenta maior precisão. / Apis mellifera is bee specie very studied under different perspectives, as for basic studies to applied ones. They have a singular nature, not only associated to economic issues as wax, honey, propolis, royal jelly and pollen production, but also for their agricultural potential as pollinators. This specie has been long aimed for morphometric studies, because of its ecological importance, easy capacity of adaptation, large distribution and for being able of efficient establishment in diverse environments. The geometric morphometric allows rigorous analyses in shape variation of a given structure in organism of diverse sizes, especially when using multivariate statistics methods, enabling the evaluation of instability in the development of an organism. The present study aim the variations of shape and size in wings and pollen basket from workers of Apis mellifera, acquired at 5 geographic regions of Brazil, using morphogeometric analyses. The existence of variation patters in shape and size of Africanized bees in Brazil, obtained 16 years ago in classic study made by Diniz-Filho and Malaspina, made possible a comparative spatialtemporal analyses with the results obtained in this study, using updated technology resources for evaluation of morphometric data, as well as the phenotypic plasticity exam of size and shape in wings and pollen basket of this specie, using fluctuating asymmetric analysis, and evaluate if diverse conditions made by anthropomorphic actions has influence on the deviation increase among bilateral symmetry of this morphological characters. The sample was made including 5 geographic regions of Brazil. By the wings size shape and multivariate analyses, it was verified the existence of a geographic pattern among Brazilian Apis mellifera populations (P< 0,001). Those geographical variations may be caused due to the big territorial expansion, alongside with the possible association of different ecoregions. It was also verified floating asymmetric in the shape of wings and pollen basket from Apis mellifera in all studied populations, however, in the multivariate analyses the asymmetry in shape was not significant in some populations, showing that, for studies of asymmetry and populational distribution, the shape of wings and pollen basket is the most indicated and precise analyses.
|
10 |
Etude des patrons de variation intraspécifique et de covariation chez les éléments conodontes / Patterns of intra-specific variation and covariation in conodont elementsSouquet, Louise 18 December 2018 (has links)
L'évolution est le produit de deux grands facteurs: l'environnement et le développement. Il est donc important de déterminer l'impact de ces deux forces lorsque l'on s'intéresse à l'évolution morphologique d'un organe. Pour cela, il est utile d'étudier l'évolution en temps profond, seul moyen d'observer les mécanismes en action sur de longs intervalles de temps et les réponses à des variations environnementales majeures. Le but de ce travail de thèse est de mieux comprendre l'évolution d'une espèce fossile: le conodonte. Ce vertébré marin dépourvus de mâchoire possède un appareil buccal composé de structures minéralisées semblables à des dents, appelées éléments conodontes. Leur fort taux d’évolution, leur enregistrement fossile long et sub-continu, et la taille importante de leurs populations font de ces éléments conodontes un modèle de choix pour répondre aux questions évolutives en temps profond. Dans la littérature, peu d'études ont tentées de quantifier la forme de ces éléments, et aucune dans un cadre développemental. Grâce à la découverte de fossiles exceptionnellement préservés, ainsi qu'à l'établissement d'une méthodologie pour quantifier les patrons de variation morphologique et de covariation de ces éléments, plusieurs facettes de l'évolution de la forme chez ces éléments ont pu être étudiées. Nous avons entre autre établis l'existence de covariations entre certains traits morphologiques, illustrant les contraintes faisant pression sur ceux-ci. Certaines contraintes sont considérées comme développementales et d'autres potentiellement mécaniques. Des directions évolutives sont également mises en évidence, contraintes par le développement qui canalise ainsi l'évolution. A l'échelle inter-genre, nous avons démontré un lien entre les changements environnementaux (notamment des variations de température) et ces directions évolutives. Ces résultats démontrent un effet croisé des forces développementales (contraignant les morphologies possible) et les forces environnementales (sélectionnant les morphologies en fonction des changements de conditions) dans l'évolution des éléments conodontes. Nous proposons des évènements d'hétérochronie comme mécanisme sous-jacent à cette évolution, potentiellement contrôlés par la température océanique. La quantification de la forme est également utilisée pour tenter de clarifier la taxonomie des neogondolellides au Trias inférieur. Ces travaux démontrent le potentiel du conodonte en tant qu'organisme modèle pour étudier l'évolution en temps profond. / Evolution is the result of two main factors: the environment and the development. In this context, untangling the impact of these two forces on the morphological evolution of a structure is of major importance. To do so, studying evolution in deep time is useful, as it is the only way to observe the mechanisms in action over a long time interval and the responses to major environmental variations. In this thesis, we aim to better understand the evolution of a fossil species: the conodont. These marine jawless vertebrates possess a feeding apparatus composed of mineralized structures comparable to teeth, called conodont elements. Their high evolutionary rate, their long and sub-continuous fossil record, and their large populations made them a relevant model to conduct evolutionary studies in deep time. In the literature, only a few studies attempt to quantify the shape of conodont elements, and never in a developmental framework. With the discovery of new exceptionally preserved fossils, and the establishment of a methodology to quantify the patterns of morphological variation and covariations in these elements, the morphological evolution of conodont elements have been studied from different angles. We have established the existence of covariations between some morphological characters, illustrating the constraints on possible morphologies. Some constraints are considered developmental, while others are potentially mechanical. Evolutionary directions are highlighted, channelled by developmental constraints. At the inter-genera scale, we demonstrated a relationship between environmental changes (especially temperature variations) and these evolutionary directions. The results revealed a combined effect of the developmental forces (that constrain the initial possible morphologies) and the evolutionary forces (selecting the fittest morphologies depending on conditions) in the conodont elements evolution. We proposed heterochrony as underlying mechanism for these patterns, potentially driven by oceanic temperature. Shape quantification is also used in an attempt to clarify the neogondolellids taxonomy of the early Triassic. This work demonstrates the conodont's potential as model organism to study evolution in deep time.
|
Page generated in 0.0781 seconds