979 resultados para SYSTEMATICS


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Sistemática, Morfologia e Biogeografia

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Five new species of Dissomphalus Ashmead, 1893 are described and illustrated, all from Espírito Santo, Brazil: D. h-ramus, D. verrucosus, D. laminaris, D. cristatus and D. scopatus. New geographic records and variation data of D. scamatus Azevedo, 1999, D. concavatus Azevedo, 1999, D. rectilineus Azevedo, 1999, D. vallensis Evans, 1979, D. gilvipes Evans, 1979, D. plaumanni Evans, 1964, D. napo Evans, 1979, D. truncatus Azevedo, 2003 and D. cornutus Evans, 1964 are included.

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Animais híbridos representam um desafio à taxonomia e sistemática, pois correspondem a unidades evolutivas geralmente sem clara delimitação morfológica, comportamental e genética. Híbridos podem ser morfologicamente intermediários aos parentais ou, devido à introgressão e retrocruzamentos, suas características podem se misturar tornando difícil sua identificação. Uma das formas de identificação de híbridos é por meio de ferramentas de biologia molecular, que ao utilizarem marcadores de DNA mitocondrial (herança exclusiva materna) e DNA nuclear (herança materna e paterna), permitem a comparação entre informações genéticas. Além da hibridização existem outras fontes de conflito entre dados moleculares provenientes do DNA mitocondrial e DNA nuclear, como por exemplo a retenção de polimorfismos ancentrais. Em localidades do Espírito Santo, Brasil, foram coletados indivíduos de morfologia distinta de Trachycephalus mesophaeus e T. nigromaculatus, que são as únicas espécies do gênero conhecidas nesse estado. Porém, estudos piloto usando o gene mitocondrial Citocromo Oxidase subunidade I (COI) agruparam esses espécimes com amostras de T. typhonius. Devido a estas incongruências, foram sequenciados fragmentos de dois genes mitocondriais - COI e Nicotinamida Desidrogenase subunidade 2 (ND2) e um exon nuclear (tirosinase) de 173 indivíduos de Trachycephalus, de forma a esclarecer as identificações taxonômicas e investigar a correspondência entre caracteres morfológicos e genéticos nesta linhagem, na sua área de ocorrência As filogenias moleculares, divergências genéticas, redes de haplótipos e polimorfismos de nucleotídeos únicos (SNPs) confirmaram as três espécies acima mencionadas como linhagens evolutivas distintas e revelaram mais sete indivíduos potencialmente híbridos, mas morfologicamente assinalados a T. mesophaeus, T. nigromaculatus ou T. typhonius.. Devido à taxa de evolução lenta da tirosinase, as espécies mais recentes T. typhonius e T. nigromaculatus parecem não terem sido sorteadas completamente nesse gene. Já T. mesophaeus, que é a espécie mais antiga das três, foi recuperada inequivocamente em todas as análises. De forma inédita, as análises moleculares evidenciaram a ocorrência de introgressão bidirecional entre T. nigromaculatus e T. typhonius e entre T. nigromaculatus e T. mesophaeus, sendo que há indícios de indivíduos F1 (cruzamentos entre espécies parentais puras gerando híbridos). A utilização do gene ND2 mostrou-se mais eficiente do que o gene COI nas filogenias e, apesar da tirosinase ser um gene nuclear de evolução lenta, contribuiu para a identificação de incongruências citonucleares. Nossos resultados mostram que a história filogenética de Trachycephalus é complexa e que o uso de marcadores nucleares de evolução mais rápida e ampliação dessas análises para outras espécies do gênero podem revelar mais eventos de hibridização.

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Dissertação de Mestrado, Ciências da Comunicação (Jornalismo), 22 de Janeiro de 2013, Universidade dos Açores.

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Studies on the feeding habits of aquatic organisms are a requirement for the management and sustainable use of marine ecosystems. The aim of the present research was to analyze the habits and trophic similarities of decapods, starfish and fish in order to propose trophic relationships between taxa, using Hennigian methods of phylogenetic systematics. This new grouping hypothesis, based on shared and exclusive food items and food types, corresponds to the broad taxonomic groups used in the analysis. Our results indicate that algae, Mollusca, Polychaeta, Crustacea, Echinodermata and Actinopterygii are the most exploited common resources among the species studied. Starfish were differentiated from other organisms for being stenophagic, and were grouped for feeding on bivalve mollusks. A larger group of fish and crustaceans shares algae and mainly crustaceans as food items. A third group united all eight species of Actinopterygii. This largest subgroup of fish is typically carnivorous, feeding on Anthozoa and a great quantity of Crustacea. Synodus foetens has a special position among fishes, due to its unique feeding on nematodes. A Euclidean distance dendrogram obtained in a previous publication grouped S. foetens with starfish. That result was based on a few non-exclusive shared similarities in feeding modes, as well as on shared absences of items, which are not an adequate grouping factor. Starfish are stenophagic, eating bivalves almost exclusively. Synodus foetens and Isopisthus parvipinnis have restricted food items, and are thus intermediary in relation to starfish, decapods, and other fish, which are euryphagous. The trophic cladogram displays details of food items, whether or not shared by all species. The resulting trophic analysis is consistent with known historical relationships.

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Twelve new species of miocene ostracoda from the Tagus basin (Portugal) are described. Paleoenvironments concerning each of these species are given.

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Abundant crops of Glycymeris have been made in the neritic bioclastic deposits of the Aquitaine Basin. After an outline about the Chattian taxa, the 5 Lower Miocene lineages are presented; G. cor is plainly predominant. Then, the Middle Miocene faunas are also detaiIed, G. inflatus and G. bimaculatus being the most frequent taxa. A test of biometrical analysis about the G. cor species is presented.

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Relatório de Estágio apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1.º e 2.º Ciclo

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Twelve new species of miocene ostracoda from the Tagus basin (Portugal) are described. Paleoenvironments concerning each of these species are given.

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Abundant crops of Glycymeris have been made in the neritic bioclastic deposits of the Aquitaine Basin. After an outline about the Chattian taxa, the 5 Lower Miocene lineages are presented; G. cor is plainly predominant. Then, the Middle Miocene faunas are also detaiIed, G. inflatus and G. bimaculatus being the most frequent taxa. A test of biometrical analysis about the G. cor species is presented.

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A collection of fossil gastropods and bivalves assembled at the Thanetian/Ypresian vertebrate site of Silveirinha (Figueira da Foz, West Central Portugal) is analysed from the point of view of systematics and palaeoecology. The diversity is scarce but the age and exceptional characteristics of the site are factors that substantiate a detailed study. The taxa identified are: Bithynia soaresi sp. nov., Gyraulus antunesi sp. nov., Chlamys sp. and Cardiiacea gen. sp. indet. The prevailing of freshwater gastropods and the occurrence of 2 fragments of marine bivalves suggest a palaeoenvironmental setting that is in conformity with interpretations already established, which are based both in sedimentologic and vertebrate data. These interpretations point out the existence of a freshwater environment opened from time to time to marine influences, resulting from a palaeoatlantic coast placed some kilometres westwards.

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The concept of species in Paleontology is of paramount importance since the correct taxonomic determinations are essential to establish the age of the beds where fossils are collected. Particularly since 1940, the concept of species from a biological context, corresponding to the variability of a set of interpopulation compatibility, led us to a new approach, in which a typological conception has been replaced by a populationist one. If the notion of species is not necessarily identical for all living organisms, the greater the difficulties of interpretation in the private world of cephalopod fossils. The latter, lend themselves well to population systematics, and where this concept of species rests primarily on the morphological similarities. Thus, the introduction of general ideas analyse "typological species", "biological species", the problem of the definition of a "population" in Paleontology, and also the importance of the biometric analysis of fossil associations. The classic examples of polymorphism amd polytypism, in existing or extinct organisms, show that the concept of fossil species, observed in a well-defined period of its lifetime, is no different from that of biological species. The study of the evolution of fossil organisms allow us to understand the modelities of evolution and the mechanisms of speciation here synthesized and fully documented, namely the anagenesis or sequential evolution and the cladogenesis or divergent evoltuion; these mechanisms are the basis of the synthetic or gradualist theory of evolution developed by Dobzhansky, Mayr, Huxley, Rensch and impson. This summary ends with a reference to the theory of punctuated (or intermittent) equilibria proposed by Gould and Eldredge, who presented a more objective interpretation of morphological gaps, considered as elements of evolution itself. The interdisciplinary collaboration between zoologists, geneticists and paleontologists, is compulsory in this domain. Paleozoology has a key role since it conveys the dynamism and depth to the dimension of space-time duality.

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This study contributes to knowledge of Anopheles species, including vectors of Plasmodium from the western Brazilian Amazon in Porto Velho, Rondônia State. The sampling area has undergone substantial environmental changes as a consequence of agricultural and hydroelectric projects, which have caused intensive deforestation and favored habitats for some mosquito species. The purpose of this study was to diagnose the occurrence of anopheline species from collections in three locations along an electric-power transmission line. Each locality was sampled three times from 2010 to 2011. The principal adult mosquitoes captured in Shannon trap were Anopheles darlingi, An. triannulatus, An. nuneztovari l.s., An.gilesi and An. costai. In addition, larvae were collected in ground breeding sites for Anopheles braziliensis, An. triannulatus, An. darlingi, An. deaneorum, An. marajoara, An. peryassui, An. nuneztovari l.s. and An. oswaldoi-konderi. Anopheles darlingi was the most common mosquito in the region. We discuss Culicidae systematics, fauna distribution, and aspects of malaria in altered habitats of the western Amazon.

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The scope of the present study encompasses the liability of the directing company for the obligations of the subordinated company. Whereas the concept of directing company is comprised in the broader context of groups of companies and, consequently, in the comprehensive framework of the relationships established among such entities, this study starts by defining the notion of groups of companies, distinguishing it from related figures. It, then, moves on to analyse the legal regime applicable to groups of companies in some legal systems deemed significant, notably the American, European and German systems. Finally, this paper scrutinizes the provisions of article 501 of the Portuguese Companies Code (“Códigodas Sociedades Comerciais”), in particular its systematics and peculiarities, so as to ascertain which is the liability scheme 2 applicable to the directing or dominant company for the obligations of the subordinates or dominated company. Pursuant to no. 1 of article 501of the CSC, the directing company’s liability for such obligations exists provided these commitments are born before, during and until such time the subordination contract is terminated. The liability of the directing or dominant company for the debts of the subordinated or dominated company ceases as of the moment when the relationship between those two entities no longer exists, with immediate effect.