Ecosystems transition quickly in the Anthropocene, whereas biodiversity adapts more slowly. Here we simulated a shifting woodland ecosystem on the Colorado Plateau of western North America by using as its proxy over space and time the fundamental niche of the Arizona black rattlesnake (Crotalus cerberus). We found an expansive (= end-of-Pleistocene) range that contracted sharply (= present), but is blocked topographically by Grand Canyon/Colorado River as it shifts predictably northwestward under moderate climate change (= 2080). Vulnerability to contemporary wildfire was quantified from available records, with forested area reduced more than 27% over 13 years. Both 'ecosystem metrics' underscore how climate and wildfire are rapidly converting the Plateau ecosystem into novel habitat. To gauge potential effects on C. cerberus, we derived a series of relevant 'conservation metrics' (i.e. genetic variability, dispersal capacity, effective population size) by sequencing 118 individuals across 846 bp of mitochondrial (mt)DNA-ATPase8/6. We identified five significantly different clades (net sequence divergence = 2.2%) isolated by drainage/topography, with low dispersal (F-ST = 0.82) and small sizes (2N(ef) = 5.2). Our compiled metrics (i.e. small-populations, topographic-isolation, low-dispersal versus conserved-niche, vulnerable-ecosystem, dispersal barriers) underscore the susceptibility of this woodland specialist to a climate and wildfire tandem. We offer adaptive management scenarios that may counterbalance these metrics and avoid the extirpation of this and other highly specialized, relictual woodland clades.

Submitted by Alessandra Vallim Lima null (alessandra_vallim@hotmail.com ) on 2017-05-31T22:11:33Z No. of bitstreams: 1 Dissertação Alessandra Vallim Lima .pdf: 2351386 bytes, checksum: 01dcf435983f13dde4b1a10a638fb67f (MD5) / Rejected by Luiz Galeffi (luizgaleffi@gmail.com), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido está sem a ficha catalográfica. A versão submetida por você é considerada a versão final da dissertação/tese, portanto não poderá ocorrer qualquer alteração em seu conteúdo após a aprovação. Corrija esta informação e realize uma nova submissão com o arquivo correto. Agradecemos a compreensão. on 2017-06-02T13:17:01Z (GMT) / Submitted by Alessandra Vallim Lima null (alessandra_vallim@hotmail.com ) on 2017-06-02T20:48:13Z No. of bitstreams: 1 Dissertação Alessandra Vallim Lima .pdf: 2354245 bytes, checksum: f5af019776c7b37355d3bef2ad53b87f (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-06-06T14:03:06Z (GMT) No. of bitstreams: 1 lima_av_me_svic.pdf: 2354245 bytes, checksum: f5af019776c7b37355d3bef2ad53b87f (MD5) / Made available in DSpace on 2017-06-06T14:03:06Z (GMT). No. of bitstreams: 1 lima_av_me_svic.pdf: 2354245 bytes, checksum: f5af019776c7b37355d3bef2ad53b87f (MD5) Previous issue date: 2017-05-02 / Nas ultimas décadas, modelagem de nicho ecológico vem recebendo maior atenção em diversas áreas da biologia devido a evolução dos computadores pessoais e aumento dos dados disponíveis utilizados para a modelagem. Os resultados obtidos podem ser utilizados em ações preventivas, tais quais manejo de espécie e acompanhamento da distribuição de espécies invasoras. Desde o aumento dessa popularidade, diversos algoritmos estão disponíveis e testes estão em andamento para averiguar suas performances em relação a diferentes filos. Invertebrados marinhos, mais especificamente cnidários, apresentam poucos estudos nesse ramo, devendo receber mais atenção nos próximos anos devido ao aumento global das populações de aguas vivas (blooms), e branqueamento em quase todos os recifes de corais. Devido a essa lacuna em informação, este grupo foi escolhido para comparar três algoritmos. Utilizamos o MAXENT, GARP e AquaMaps em suas formas de desktop e os selecionamos baseado em outros estudos comparando algoritmos. Utilizamos diferentes organismos do filo cnidária, Lychnorhiza lucerna, Chrysaora lactea, Phyllorhiza punctata, Tamoya haplonema, Ceriantheomorphe brasiliensis e Mussismilia hispida, para comparar os algoritmos e averiguar qual demonstrou melhor performance. Nossos resultados mostram que o MAXENT superou os outros algoritmos tanto com relação a Área Sob a Curva ROC (AUC), quanto com relação aos mapas de distribuição. O GARP apresentou resultados variados com mapas generalizados e AquaMaps foi o menos confiável. Nossos resultados são similares aqueles encontrados em diversas publicações, significando então, que o MAXENT é o algoritmo mais confiável em se tratando da modelagem de nicho desses organismos. / Recently, ecological niche modelling has been receiving more attention in several areas in biology, due to the evolution of personal computers, and the increasing availability of data used in modelling. The results obtained can be used in preventive actions such as species management and invasive species distribution. Since its increasing popularity, several algorithms are available and undergoing tests regarding their performance towards different phylum. Marine invertebrates, more specifically cnidarians, present few studies on this field, and should receive closer attention in the next years due to worldwide increases in jellyfish population (blooms), and bleaching in almost every known shallow water coral reef. Because of this gap of information, we chose this still poor studied group to compare three algorithms. We used MAXENT, GARP and AquaMaps in its desktop form and selected them based on other studies comparing algorithms. Our aim was to, based on different organisms of the phylum Cnidaria, Lychnorhiza lucerna, Chrysaora lactea, Phyllorhiza punctata, Tamoya haplonema, Ceriantheomorphe brasiliensis and Mussismilia hispida, compare those algorithms and examine which one performed the best. Our results shown that MAXENT outperformed the other algorithms both regarding de Area Under the ROC Curve (AUC) and the map distribution. GARP show varying results with generalized maps and AquaMaps was the least accurate of them. Our results are similar to those found in other papers, thus meaning that MAXENT is the most reliable software when it comes to modelling these animals.

Estudos filogeográficos almejam compreender a distribuição da diversidade genética de uma espécie. E ainda, estudos de organismos co-distribuídos permitem inferir os processos atuantes na história da região de sua ocorrência. Dentro desse contexto o presente trabalho se propôs a estudar a filogeografia de duas espécies de passeriformes endêmicos da Mata Atlântica, Chiroxiphia caudata e Hemitrccus diops, visando auxiliar na compreensão da evolução da biota neste bioma. Foram utilizados indivíduos amostrados ao longo da distribuição das espécies: 112 de C. caudata e 82 de H. diops. Foram obtidas sequências parciais do gene mitocondrial ND2 (932 pb e 910 pb, respectivamente para C. caudata e H. diops), de um íntron do gene G3PDH (303 pb e 323 pb, respectivamente), e de íntrons do gene ODC (517 pb) para H. diops. Não foi encontrada estrutura filogeográfica em C. caudata, que apresentou sinal de expansão recente. A ausência de estrutura pode ser decorrência do longo tempo de geração da espécie. Modelos de distribuição da espécie durante o último máximo glacial apresentaram dois cenários divergentes, um com distribuição predominantemente ao norte e outro com distribuição similar ou maior que a atual. Em contraste, foi encontrada uma baixa, mas clara estrutura filogeográfica em H. diops. Os sinais de alteração demográfica, entretanto, são menos claros, havendo tanto sinal de expansão quanto de estabilidade populacional ao longo dos ciclos glaciais. A diversidade de padrões filogeográficos encontrada na presente Dissertação é congruente com achados sobre a distribuição da diversidade genética de outros organismos da Mata Atlântica, e ultimamente, refletem a complexidade do bioma como um todo / Phylogeographic studies aim to analyze the distribution of the genetic diversity of a given species. In addition, studies of co-distributed organisms enable to infer historic processes acting on the region where they occur. In this context the present work intended to study the phylogeography of two Atlantic Forest endemic birds, Chiroxiphia caudata and Hemitriccus diops to help to understand how this biome evolved. 112 individuals of C. caudata and 82 of H. diops were sampled throughout their distributions. We obtained partial sequences of the mitochondrial gene ND2 (932 bp and 910 bp, respectively, for C. caudata and H. diops), of an intron of the G3PDH gene (303 bp and 323 bp, respectively), and introns from the ODC gene (517 bp) of H. diops. No signal of phylogeographic structure was found for C. caudata,, which exhibits signal of recent demographic expansion. The absence of population structure may be a consequence of the species long generation time. Models of distribution during the last glacial maximum exhibited two discordant scenarios: one with its main distribution in the north and another with a similar or larger distribution than the current one. In contrast, we found a shallow, but clear phylogeographic structure for H. diops. The demographic history, however, was not clear, with signal of both demographic expansion and stability during the glacial cycles. The different phylogeographic patterns found here are congruent with the diversity of patterns observed in other Atlantic Forest organisms, reflecting the complex history of the biome

Orientador: Ingrid Koch / Resumo: Neste estudo, nós desenvolvemos marcadores moleculares e aplicamos abordagens integrativas em filogeografia e ecologia para investigar e descrever a história biogeográfica das chapadas da região oeste do Cerrado brasileiro. Utilizando como modelo duas espécies do gênero Rauvolfia L. (Apocynaceae, Rauvolfioideae), Rauvolfia weddelliana Müll.Arg. e Rauvolfia gracilis I.Koch & Kin.-Gouv., típicas destes ambientes, nós desenvolvemos um conjunto de marcadores nucleares microssatélites e sequenciamos espaçadores de cloroplasto, com os quais estimamos métricas de diversidade genética e estruturação populacional. A partir destes dados, nós reconstruímos relações filogenéticas entre as linhagens, estimamos tempos de divergência e realizamos simulações demográficas e modelos de distribuição, com o intuito de testar possíveis cenários biogeográficos. Em sequência, nós desenvolvemos modelos de distribuição potencial em escala de comunidade e análises espaciais, para estimar o impacto relativo das flutuações climáticas do Pleistoceno sobre o endemismo no Cerrado, quando comparadas a outros processos. Os resultados estão apresentados em três capítulos. No primeiro, intitulado “Development and cross-validation of microsatellite markers for Rauvolfia weddelliana Müll.Arg. (Apocynaceae) species complex”, nós descrevemos o desenvolvimento de uma biblioteca de microssatélites específica para R. weddelliana e testamos sua transferabilidade para a espécie R. gracilis. Nós isolamos dez marcadores ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this study, we developed molecular markers and applied integrative approaches in phylogeography and ecology to investigate and describe the biogeographic history of the plateaus of the west region of the Cerrado in Brazil. Using as models two species of the genus Rauvolfia L. (Apocynaceae, Rauvolfioideae), Rauvolfia weddelliana Müll.Arg. and Rauvolfia gracilis I.Koch & Kin.-Gouv., typical from these habits, we developed a set of nuclear microsatellite markers and sequenced chloroplast spacers, which we used to estimate metrics of genetic diversity and population structure. From this data, we reconstructed phylogenetic relationships between lineages, estimated divergence times and conducted demographic simulations and distribution models, intending to test possible biogeographic scenarios. In sequence, we also developed community wise models of potential distribution and conducted spatial analysis to estimate the relative impact of climatic shifts of the Pleistocene on the endemism of the Cerrado, when compared to other processes. Our results are presented in three chapters. In the first, entitled “Development and cross-validation of microsatellite markers for Rauvolfia weddelliana Müll.Arg. (Apocynaceae) species complex”, we describe the development of a specific microsatellite library to R. weddelliana and tested its transferability to the species R. gracilis . We isolated ten transferable markers with high polymorphism content that may now be applied to genetics studies ... (Complete abstract click electronic access below) / Doutor

The spread of an agricultural lifestyle played a crucial role in the development of social complexity and in defining trajectories of human history. This dissertation presents the results of research into how agricultural strategies were modified during the spread of agriculture into Southwest China. By incorporating advances from the fields of plant biology and ecological niche modeling into archaeological research, this dissertation addresses how humans adapted their agricultural strategies or invented appropriate technologies to deal with the challenges presented by the myriad of ecological niches in southwest China. This dissertation uses ecological niche modeling to examine the options and constraints associated with practicing different types of agriculture in the specific ecological niches of southwest China. The predictions made by these models are then tested against archaeobotanical data from a series of sites from across the region. This approach allows one to understand how the spread of agriculture took place in its particular social and economic contexts. / Anthropology

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Agradecemos a compreensão. on 2018-05-11T17:00:35Z (GMT) / Submitted by João De Deus Vidal Júnior (jd.vidal27@gmail.com) on 2018-05-11T18:26:13Z No. of bitstreams: 1 Tese_JVidal.pdf: 12476337 bytes, checksum: b4bd90a360a05a2358c8c188653a9128 (MD5) / Approved for entry into archive by Sulamita Selma C Colnago null (sulamita@btu.unesp.br) on 2018-05-11T19:39:40Z (GMT) No. of bitstreams: 1 vidaljr_jd_dr_bot.pdf: 12476337 bytes, checksum: b4bd90a360a05a2358c8c188653a9128 (MD5) / Made available in DSpace on 2018-05-11T19:39:40Z (GMT). No. of bitstreams: 1 vidaljr_jd_dr_bot.pdf: 12476337 bytes, checksum: b4bd90a360a05a2358c8c188653a9128 (MD5) Previous issue date: 2018-03-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste estudo, nós desenvolvemos marcadores moleculares e aplicamos abordagens integrativas em filogeografia e ecologia para investigar e descrever a história biogeográfica das chapadas da região oeste do Cerrado brasileiro. Utilizando como modelo duas espécies do gênero Rauvolfia L. (Apocynaceae, Rauvolfioideae), Rauvolfia weddelliana Müll.Arg. e Rauvolfia gracilis I.Koch & Kin.-Gouv., típicas destes ambientes, nós desenvolvemos um conjunto de marcadores nucleares microssatélites e sequenciamos espaçadores de cloroplasto, com os quais estimamos métricas de diversidade genética e estruturação populacional. A partir destes dados, nós reconstruímos relações filogenéticas entre as linhagens, estimamos tempos de divergência e realizamos simulações demográficas e modelos de distribuição, com o intuito de testar possíveis cenários biogeográficos. Em sequência, nós desenvolvemos modelos de distribuição potencial em escala de comunidade e análises espaciais, para estimar o impacto relativo das flutuações climáticas do Pleistoceno sobre o endemismo no Cerrado, quando comparadas a outros processos. Os resultados estão apresentados em três capítulos. No primeiro, intitulado “Development and cross-validation of microsatellite markers for Rauvolfia weddelliana Müll.Arg. (Apocynaceae) species complex”, nós descrevemos o desenvolvimento de uma biblioteca de microssatélites específica para R. weddelliana e testamos sua transferabilidade para a espécie R. gracilis. Nós isolamos dez marcadores transferíveis, com alto conteúdo de polimorfismos que podem agora ser aplicados em estudos genéticos para o grupo, e também demonstramos a diploidia das espécies através do padrão de bandas de cada lócus. No segundo capítulo, intitulado “Phylogeography and paleodistribution of Rauvolfia weddelliana Müll.Arg. and Rauvolfia gracilis I.Koch & Kin.-Gouv. (Apocynaceae)”, nós aplicamos estes marcadores em conjunto com espaçadores de cloroplasto para testar, através de análises demográficas e modelos de nicho, os impactos das flutuações climáticas nas populações de R. weddelliana e R. gracilis. Nossas análises recuperaram duas linhagens com origem anterior ao Pleistoceno, coincidindo com o soerguimento do Planalto Central Brasileiro, que sofreram retração interglacial durante o Pleistoceno. Apesar de nossos modelos de distribuição terem apresentado resultado contrário a retração interglacial, eles recuperaram a mesma divergência norte-sul, também anterior ao último eventos de glaciação. Estes resultados sugerem que as savanas dos planaltos do oeste do Cerrado provavelmente configuram refúgios interglaciais. No terceiro capítulo, nós testamos este padrão, descrevendo a estabilidade relativa de chapadas e vales e modelando as distribuições potenciais de espécies típicas destes ambientes. Este trabalho contribui para a discussão sobre os impactos do clima do Pleistoceno e dos processos geológicos do Mioceno na diversificação do complexo domínio dos Cerrados. / In this study, we developed molecular markers and applied integrative approaches in phylogeography and ecology to investigate and describe the biogeographic history of the plateaus of the west region of the Cerrado in Brazil. Using as models two species of the genus Rauvolfia L. (Apocynaceae, Rauvolfioideae), Rauvolfia weddelliana Müll.Arg. and Rauvolfia gracilis I.Koch & Kin.-Gouv., typical from these habits, we developed a set of nuclear microsatellite markers and sequenced chloroplast spacers, which we used to estimate metrics of genetic diversity and population structure. From this data, we reconstructed phylogenetic relationships between lineages, estimated divergence times and conducted demographic simulations and distribution models, intending to test possible biogeographic scenarios. In sequence, we also developed community wise models of potential distribution and conducted spatial analysis to estimate the relative impact of climatic shifts of the Pleistocene on the endemism of the Cerrado, when compared to other processes. Our results are presented in three chapters. In the first, entitled “Development and cross-validation of microsatellite markers for Rauvolfia weddelliana Müll.Arg. (Apocynaceae) species complex”, we describe the development of a specific microsatellite library to R. weddelliana and tested its transferability to the species R. gracilis . We isolated ten transferable markers with high polymorphism content that may now be applied to genetics studies on the group, and also demonstrated the diploidy for these species though the patterns of bands for each locus. In the second chapter, entitled “Phylogeography and paleodistribution of Rauvolfia weddelliana Müll.Arg. and Rauvolfia gracilis I.Koch & Kin.-Gouv. (Apocynaceae)”, we applied these markers, along with sequences of chloroplast spacers to test, with demographic analysis and niche models, the impacts of the climatic fluctuations on the populations of R. weddelliana and R. gracilis . Our analysis recovered two lineages with origin prior to Pleistocene, coinciding with the Brazilian Central Plateau uplift. These lineages underwent interglacial retractions along the Pleistocene. Despite distribution models presented results that are contrary to the interglacial retraction, they recovered the same north-south divergence, also predating the Last Glacial Maximum. These results suggest that the savannas in the plateaus of the western Cerrado are potentially configuring interglacial refugia. In the third chapter, we tested this pattern, by describing the relative stability of plateaus and valleys and modelling the potential distributions of species typical from these environments. This study contributes to the discussions about the impacts of the Pleistocene climate and the geological processes of the Miocene on the diversification the complex Cerrado domain.

Estudos filogeográficos almejam compreender a distribuição da diversidade genética de uma espécie. E ainda, estudos de organismos co-distribuídos permitem inferir os processos atuantes na história da região de sua ocorrência. Dentro desse contexto o presente trabalho se propôs a estudar a filogeografia de duas espécies de passeriformes endêmicos da Mata Atlântica, Chiroxiphia caudata e Hemitrccus diops, visando auxiliar na compreensão da evolução da biota neste bioma. Foram utilizados indivíduos amostrados ao longo da distribuição das espécies: 112 de C. caudata e 82 de H. diops. Foram obtidas sequências parciais do gene mitocondrial ND2 (932 pb e 910 pb, respectivamente para C. caudata e H. diops), de um íntron do gene G3PDH (303 pb e 323 pb, respectivamente), e de íntrons do gene ODC (517 pb) para H. diops. Não foi encontrada estrutura filogeográfica em C. caudata, que apresentou sinal de expansão recente. A ausência de estrutura pode ser decorrência do longo tempo de geração da espécie. Modelos de distribuição da espécie durante o último máximo glacial apresentaram dois cenários divergentes, um com distribuição predominantemente ao norte e outro com distribuição similar ou maior que a atual. Em contraste, foi encontrada uma baixa, mas clara estrutura filogeográfica em H. diops. Os sinais de alteração demográfica, entretanto, são menos claros, havendo tanto sinal de expansão quanto de estabilidade populacional ao longo dos ciclos glaciais. A diversidade de padrões filogeográficos encontrada na presente Dissertação é congruente com achados sobre a distribuição da diversidade genética de outros organismos da Mata Atlântica, e ultimamente, refletem a complexidade do bioma como um todo / Phylogeographic studies aim to analyze the distribution of the genetic diversity of a given species. In addition, studies of co-distributed organisms enable to infer historic processes acting on the region where they occur. In this context the present work intended to study the phylogeography of two Atlantic Forest endemic birds, Chiroxiphia caudata and Hemitriccus diops to help to understand how this biome evolved. 112 individuals of C. caudata and 82 of H. diops were sampled throughout their distributions. We obtained partial sequences of the mitochondrial gene ND2 (932 bp and 910 bp, respectively, for C. caudata and H. diops), of an intron of the G3PDH gene (303 bp and 323 bp, respectively), and introns from the ODC gene (517 bp) of H. diops. No signal of phylogeographic structure was found for C. caudata,, which exhibits signal of recent demographic expansion. The absence of population structure may be a consequence of the species long generation time. Models of distribution during the last glacial maximum exhibited two discordant scenarios: one with its main distribution in the north and another with a similar or larger distribution than the current one. In contrast, we found a shallow, but clear phylogeographic structure for H. diops. The demographic history, however, was not clear, with signal of both demographic expansion and stability during the glacial cycles. The different phylogeographic patterns found here are congruent with the diversity of patterns observed in other Atlantic Forest organisms, reflecting the complex history of the biome

In most tropical river systems there has been a lack of integrated ecological research to investigate the dynamics and impacts of invasive species on recipient river systems. This is in sharp contrast to temperate river systems. This thesis investigated the nature, extent, and impact of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), on indigenous congenerics within the Limpopo River basin in northern South Africa. An integrated approach was adopted to gain a better understanding of factors that allow Nile tilapia to be a successful invader and also to gain an insight into its invasion rate and conservation implications within South Africa. Morphometric and genetic variation between Nile tilapia, indigenous congenerics and their associated hybrids were determined. Intermediate meristic characters obscured the identification of hybrid specimens from pure morpho-specimens and species identity was only confirmed through mtDNA analysis. Preliminary evidence points to unidirectional hybridization among Oreochromis congeners in the Limpopo River system. The hypothesis that bigger Nile tilapia males may have a competitive advantage over spawning grounds and in female mate choice is proposed. The trophic ecology of Nile tilapia was investigated using both stomach contents and stable isotope analysis. A high similarity in stomach contents was observed but interspecific differences were revealed in the isotopic composition of diets that suggest fine scale patterns of resource partitioning that could be achieved by the ability of fish to selectively feed on what is immediately available and the ability to perceive the dynamics that determine food resource availability. Ecological niche models were used to determine the potential invasive range of Nile tilapia and revealed broad invasive potential over most river systems in southern Africa that overlapped the natural range of endemic congenerics. It was noted that model performance and the degree of niche conservatism varied significantly with variable selection and spatial extent of study area. This implied that the spatial distribution of suitable and unsuitable environmental variables varied between the native and introduced ranges of Nile tilapia and also indicated the ability of Nile tilapia to survive in conditions incongruent with its native range. The extreme hardiness and adaptive life history characteristics of Nile tilapia have probably predisposed it to be a successful invader in novel systems within southern Africa. Lastly, a qualitative risk assessment method was developed as a potential application to determine the risk of establishment and spread of the invasive Nile tilapia. Results showed that in the absence of quantitative data on ecosystem structure and functioning, habitat suitability analysis in terms of known physiological tolerance limits to minimum water temperature, presence or absence of dams, seasonality of river flows and the presence of indigenous fish species of concern could be adequate for identifying vulnerable river systems. The model developed also provides an objective method that is easy to implement, modify and improve on as new data become available. Furthermore, the model can be applied to highlight areas of uncertainty where future research should be directed. / Thesis (PhD)--University of Pretoria, 2012. / Zoology and Entomology / Unrestricted

No description available.

Quels sont les grands patrons de distribution des espèces et quels sont les facteurs qui les contrôlent? Ces questions sont au cœur des problématiques macroécologiques et prennent un intérêt tout particulier au regard du réchauffement climatique global actuel. L’objectif principal de ce travail de thèse était de déterminer les patrons de distribution actuels des espèces d’oursins antarctiques et subantarctiques à l’échelle de l’océan Austral et de mettre en évidence les facteurs qui contrôlent ces distributions. La modélisation des niches écologiques d’une vingtaine d’espèces d’oursins a permis de mettre en évidence deux grands patrons de distribution : (1) un premier représenté par les espèces dont la distribution n’est pas limitée au sud du Front Polaire et s’étend des côtes antarctiques aux zones subantarctiques et tempérées froides et (2) un deuxième constitué d’espèces restreintes à la zone antarctique. Au sein de ces deux patrons, cinq sous-patrons ont également pu être défini sur la base de différences de distribution latitudinale et bathymétrique entre groupes d’espèces. Cette approche biogéographique par modélisation de niche écologique a été complétée par l’analyse de similarité de l’ensemble des faunes d’oursins, de bivalves et de gastéropodes, au niveau spécifique et générique, entre biorégions de l’océan Austral. Cette analyse démontre qu’il existe chez les oursins et les bivalves des connexions fauniques entre l’Amérique du Sud et les zones subantarctiques ainsi qu’une séparation entre l’Est et l’Ouest antarctique. Au contraire, les faunes de gastéropodes subantarctiques montrent des affinités plutôt antarctiques que sud-américaines, l’Antarctique ne formant qu’une unique province pour ce clade. Ces différences entre clades sont interprétées comme étant le résultat d’histoires évolutive et biogéographique distinctes entre oursins et bivalves d’une part et gastéropodes d’autre part. L’hypothèse d’une réponse évolutive différente des clades aux changements environnementaux survenus au cours du Cénozoïque est avancée. Enfin, l’existence de connexions fauniques trans-antarctiques est mise en évidence dans l’étude des trois clades ; celles-ci sont interprétées comme le résultat de la dislocation de la calotte ouest-antarctique et l’ouverture de bras de mer trans-antarctiques au cours du Pléistocène. Parmi les paramètres environnementaux utilisés dans la modélisation des niches écologiques, les résultats montrent que trois paramètres jouent un rôle majeur dans la distribution des oursins : la profondeur, la couverture de glace et la température des eaux de surface. Toutefois, l’importance relative de ces paramètres diffère selon les espèces d’oursins étudiées. L’étude du genre Sterechinus souligne tout particulièrement ces différences. En effet, l’espèce S. neumayeri est plus sensible aux conditions environnementales qui prédominent près des côtes antarctiques (température des eaux de surface et couverture de glace), alors que S. antarcticus semble être beaucoup moins contraint par ces mêmes paramètres. La distribution potentielle de S. antarcticus est d’ailleurs beaucoup plus étendue en latitude. Cependant, S. antarcticus n’est pas présent sur l’ensemble de son aire de distribution potentielle, ceci pouvant être expliqué alternativement par le résultat (1) de facteurs océanographiques (rôle de barrière biogéographique joué par le Front Polaire), (2) d’interactions biotiques (phénomènes de compétition inter-spécifique) et (3) du contexte temporel (colonisation toujours en cours). / What are the forcing factors and main patterns of species distribution? This question is the core of macroecological issues and is of particular interest in the present context of global warming. The main objectives of this thesis were to determine the current distribution patterns of Antarctic and sub-Antarctic echinoid species at the scale of the whole Southern Ocean and to highlight the forcing factors that control them. The ecological niche modelling of 19 echinoid species showed that distribution is mainly structured in two patterns: (1) a first one represented by species that are not limited to the south of the Polar Front and distributed from the Antarctic coasts to the sub-Antarctic and cold temperate areas, and (2) a second one with species restricted to the Antarctic area. Within these two main patterns, five sub-patterns were also identified that depend on differences in the latitudinal and depth range of species groupings. In addition to this approach of biogeography by ecological niche modelling, a similarity analysis of echinoid, bivalve and gastropod fauna between bioregions of the Southern Ocean was performed at species and genus levels. This analysis reveals faunal connections between southern South America and sub-Antarctic areas in echinoids and bivalves, along with a partition between the East and West Antarctic. On the contrary, sub-Antarctic gastropod fauna show Antarctic rather than South American affinities and the Antarctic form a sole and unique province in this clade. These differences between clades are interpreted as the result of distinct biogeographic and evolutionary histories between echinoids and bivalves on the one hand, and gastropods on the other hand. The proposed hypothesis is that clades developped different evolutionary responses to the environmental changes that occurred during the Cenozoic. Finally, in the three clades, trans-Antarctic faunal connections are shown and interpreted as a result of West Antarctic Ice Sheet collapses and the setting up of trans-Antarctic sea-ways during the Pleistocene. Among the environmental parameters used for the ecological niche modelling, results show that the three following parameters play the main part in echinoid distribution: depth, sea-ice cover and sea surface temperature. However, the relative importance of these parameters depends on the species under studies. These differences are particularly emphasized in the case study of the genus Sterechinus. The species S. neumayeri is indeed the most dependent on environmental conditions that prevail along the Antarctic coasts (sea surface temperature and sea-ice cover), while S. antarcticus doesn’t seem to be so much under the control of these parameters. Accordingly, the potential distribution of S. antarcticus in latitude is the most extended. However, S. antarcticus is not present over the whole area of its potential distribution, what can be explained as the result of either (1) oceanographic factors (role of the Polar Front as a biogeographical barrier), (2) biotic interactions (inter-specific competition) or (3) the temporal context (still ongoing colonization).