985 resultados para COMPARATIVE ADVANTAGE


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Understanding the evolution of intraspecific variance is a major research question in evolutionary biology. While its importance to processes operating at individual and population levels is well-documented, much less is known about its role in macroevolutionary patterns. Nevertheless, both experimental and theoretical evidence suggest that the intraspecific variance is susceptible to selection, can transform into interspecific variation and, therefore, is crucial for macroevolutionary processes. The main objectives of this thesis were: (l) to investigate which factors impact evolution of intraspecific variation in Polygonaceae and determine if evolution of intraspecific variation influences species diversification; and (2) to develop a novel comparative phylogenetic method to model evolution of intraspecific variation. Using the buckwheat family, Polygonaceae, as a study system, I demonstrated which life-history and ecological traits are relevant to the evolution of intraspecific variation. I analyzed how differential intraspecific variation drives species diversification patterns. I showed with computer simulations the shortcomings of existing comparative methods with respect to intraspecific variation. I developed a novel comparative model that readily incorporates the intraspecific variance into phylogenetic comparative methods. The obtained results are complimentary, because they affect both empirical and methodological aspects of comparative analysis. Overall, I highlight that intraspecific variation is an important contributor to the macroevolutionary patterns and it should be explicitly considered in the comparative phylogenetic analysis. - En biologie évolutive comprendre l'évolution de la variance intraspécifique est un axe de recherche majeur. Bien que l'importance de cette variation soit bien documentée au niveau individuel et populationnel, on en sait beaucoup moins sur son rôle au niveau macroévolutif. Néanmoins, des preuves expérimentales et théoriques suggèrent que la variance intraspécifique est sensible à la sélection et peut se transformer en variation interspécifique. Par conséquent, elle est cruciale pour mieux comprendre les processus macroévolutifs. Les principaux objectifs de ma thèse étaient : (i) d'enquêter sur les facteurs qui affectent l'évolution de la variation intraspécifique chez les Polygonaceae et de déterminer si l'évolution de cette dernière influence la diversification des espèces, et (2) de développer une nouvelle méthode comparative permettant de modéliser l'évolution de la variation intraspécifique dans un cadre phylogénétique. En utilisant comme système d'étude la famille du sarrasin, les Polygonacées, je démontre que les traits d'histoire de vie sont pertinents pour comprendre l'évolution de la variation intraspécifique. J'ai également analysé l'influence de la variation intraspécifique au niveau de la diversification des espèces. J'ai ensuite démontré avec des données simulées les limites des méthodes comparatives existantes vis à vis de la variation intraspécifique. Finalement, j'ai développé un modèle comparatif qui intègre facilement la variance intraspécifique dans les méthodes comparatives phylogénétiques existantes. Les résultats obtenus lors de ma thèse sont complémentaires car ils abordent aspects empiriques et méthodologiques de l'analyse comparative. En conclusion, je souligne que la variation intraspécifique est un facteur important en macroévolution et qu'elle doit être explicitement considérée lors d'analyses comparatives phylogénétiques.

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In order to investigate the affinities of the hitherto considered Neotropical Cleomenini genera, a detailed morphological comparative study was carried out based on representatives of their type species and other congeneric species. The results, when compared with representatives of Cleomenes Thomson and other non Neotropical Cleomenini genera together with representatives of Rhopalophorini Blanchard and Rhinotragini Thomson, show that: 1) Listroptera Audinet-Serville, 1834, Dihammaphora Chevrolat, 1859, Haenkea Tippmann, 1953, Aguassay Napp & Mermudes, 2001 and Timabiara Napp & Mermudes, 2001 form a very homogeneous group, not related to other Cleomenini, but sharing several synapomorphies with the Rhopalophorini; therefore they are herein transferred to this tribe; 2) the affinities of Dihammaphoroides Zajciw, 1967, were not clearly defined, needing further investigations; nevertheless, the genus is tentatively included in Rhopalophorini due to its morphological similarity with Dihammaphora and allied genera; 3) Pandrosos Bates, 1867 is brought back to Rhinotragini, in which it was originally placed. Therefore, the tribe Cleomenini Lacordaire is no longer represented in the New World.

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Holymenia clavigera (Herbst, 1784) and Anisoscelis foliacea marginella (Dallas, 1852) (Hemiptera, Coreidae) present a remarkable similarity regarding egg and nymphal morphology. On the contrary, their adult stages are remarkably different. This study describes and compares the immature stages of these two coreid species. Excepting for the last instar and the shape of the hind tibia from third to last instar, nymphs of both species were identical in their gross morphologies and ultrastructures. However, H. clavigera was significantly larger than A. foliacea marginella in all stages. Thus, we suggest that these species may have evolved through evolutionary convergence, parsimony between the immature stages after speciation, Müllerian mimicry or genetic drift.

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OBJECTIVE:: Report of a 16q24.1 deletion in a premature newborn, demonstrating the usefulness of array-based comparative genomic hybridization in persistent pulmonary hypertension of the newborn and multiple congenital malformations. DESIGN:: Descriptive case report. SETTING:: Genetic department and neonatal intensive care unit of a tertiary care children's hospital. INTERVENTIONS:: None. PATIENT:: We report the case of a preterm male infant, born at 26 wks of gestation. A cardiac malformation and bilateral hydronephrosis were diagnosed at 19 wks of gestation. Karyotype analysis was normal, and a 22q11.2 microdeletion was excluded by fluorescence in situ hybridization analysis. A cesarean section was performed due to fetal distress. The patient developed persistent pulmonary hypertension unresponsive to mechanical ventilation and nitric oxide treatment and expired at 16 hrs of life. MEASUREMENTS AND MAIN RESULTS:: An autopsy revealed partial atrioventricular canal malformation and showed bilateral dilation of the renal pelvocaliceal system with bilateral ureteral stenosis and annular pancreas. Array-based comparative genomic hybridization analysis (Agilent oligoNT 44K, Agilent Technologies, Santa Clara, CA) showed an interstitial microdeletion encompassing the forkhead box gene cluster in 16q24.1. Review of the pulmonary microscopic examination showed the characteristic features of alveolar capillary dysplasia with misalignment of pulmonary veins. Some features were less prominent due to the gestational age. CONCLUSIONS:: Our review of the literature shows that alveolar capillary dysplasia with misalignment of pulmonary veins is rare but probably underreported. Prematurity is not a usual presentation, and histologic features are difficult to interpret. In our case, array-based comparative genomic hybridization revealed a 16q24.1 deletion, leading to the final diagnosis of alveolar capillary dysplasia with misalignment of pulmonary veins. It emphasizes the usefulness of array-based comparative genomic hybridization analysis as a diagnostic tool with implications for both prognosis and management decisions in newborns with refractory persistent pulmonary hypertension and multiple congenital malformations.

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La réforme de la péréquation financière et de la répartition des tâches entre la Confédération et les cantons (RPT) entrera en vigueur le 1er janvier 2008. Elle prévoit notamment le transfert de la responsabilité des institutions pour personnes handicapées de la Confédération aux cantons. Ce mémoire se concentre sur ce domaine particulier en décrivant de quelle manière les cantons se préparent pour assumer leurs nouvelles responsabilités et comment ils envisagent de redéfinir leurs relations avec les institutions spécialisées et les personnes handicapées. Par une analyse comparative menée dans les cantons de Neuchâtel, Vaud, Valais, Bâle-Ville et Bâle-Campagne des différences intercantonales importantes sont mise en évidence et permettent d'aborder la problématique générale de la mise en oeuvre d'une politique sociale dans un Etat fédéral.

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The Maximum Capture problem (MAXCAP) is a decision model that addresses the issue of location in a competitive environment. This paper presents a new approach to determine which store s attributes (other than distance) should be included in the newMarket Capture Models and how they ought to be reflected using the Multiplicative Competitive Interaction model. The methodology involves the design and development of a survey; and the application of factor analysis and ordinary least squares. Themethodology has been applied to the supermarket sector in two different scenarios: Milton Keynes (Great Britain) and Barcelona (Spain).

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Gene duplications can have a major role in adaptation, and gene families underlying chemosensation are particularly interesting due to their essential role in chemical recognition of mates, predators and food resources. Social insects add yet another dimension to the study of chemosensory genomics, as the key components of their social life rely on chemical communication. Still, chemosensory gene families are little studied in social insects. Here we annotated chemosensory protein (CSP) genes from seven ant genomes and studied their evolution. The number of functional CSP genes ranges from 11 to 21 depending on species, and the estimated rates of gene birth and death indicate high turnover of genes. Ant CSP genes include seven conservative orthologous groups present in all the ants, and a group of genes that has expanded independently in different ant lineages. Interestingly, the expanded group of genes has a differing mode of evolution from the orthologous groups. The expanded group shows rapid evolution as indicated by a high dN/dS (nonsynonymous to synonymous changes) ratio, several sites under positive selection and many pseudogenes, whereas the genes in the seven orthologous groups evolve slowly under purifying selection and include only one pseudogene. These results show that adaptive changes have played a role in ant CSP evolution. The expanded group of ant-specific genes is phylogenetically close to a conservative orthologous group CSP7, which includes genes known to be involved in ant nestmate recognition, raising an interesting possibility that the expanded CSPs function in ant chemical communication.

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The Microbe browser is a web server providing comparative microbial genomics data. It offers comprehensive, integrated data from GenBank, RefSeq, UniProt, InterPro, Gene Ontology and the Orthologs Matrix Project (OMA) database, displayed along with gene predictions from five software packages. The Microbe browser is daily updated from the source databases and includes all completely sequenced bacterial and archaeal genomes. The data are displayed in an easy-to-use, interactive website based on Ensembl software. The Microbe browser is available at http://microbe.vital-it.ch/. Programmatic access is available through the OMA application programming interface (API) at http://microbe.vital-it.ch/api.

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We argue that during the crystallization of common and civil law in the 19th century, the optimal degree of discretion in judicial rulemaking, albeit influenced by the comparative advantages of both legislative and judicial rulemaking, was mainly determined by the anti-market biases of the judiciary. The different degrees of judicial discretion adopted in both legal traditions were thus optimally adapted to different circumstances, mainly rooted in the unique, market-friendly, evolutionary transition enjoyed by English common law as opposed to the revolutionary environment of the civil law. On the Continent, constraining judicial discretion was essential for enforcing freedom of contract and establishing a market economy. The ongoing debasement of pro-market fundamentals in both branches of the Western legal system is explained from this perspective as a consequence of increased perceptions of exogenous risks and changes in the political system, which favored the adoption of sharing solutions and removed the cognitive advantage of parliaments and political leaders.

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Residence advantage in heterospecific territorial disputes of Erythrodiplax Brauer species (Odonata, Libellulidae). Territories are the outcome of interactions determining where and how long individuals settle. To odonate species, aggressive disputes are not so common since the outcome can be predetermined by advantages such as residency, age, and body size. However, it is possible to predict that at heterospecific disputes, larger body-sized or more aggressive species have some profits overcoming these individual advantages, generating patterns of species hierarchy. Here, I studied the aggressiveness of five Erythrodiplax species (Odonata, Libellulidae) during territorial disputes and verified if larger body-sized species are more aggressive than smaller ones or if the residence advantage prevails on the heterospecific disputes. Larger species were not more aggressive than smaller ones and winners of intra- and interspecific territorial disputes were defined mainly by the residence. So, the residence advantage between heterospecific opponents appears to prevail over any other asymmetry among these species. This pattern may occur because, despite the territorial behaviour in dragonfly males, heterospecific disputes may not increment male reproductive success because it may not increase their access to females.