No description available.

No description available.

Les Loricariinae appartiennent à la famille des poissons-chats néotropicaux cuirassés Loricariidae, la famille de poissons-chats la plus riche en espèce au monde, et se caractérisent par un pédoncule caudal long et aplati et par l’absence de nageoire adipeuse. Préalablement aux études évolutives réalisées, une phylogénie exhaustive et robuste a été établie sur la base de données mitochondriales et nucléaires. Cette phylogénie a ensuite été utilisée dans des analyses multivariées et multi-tableaux afin de révéler les principales tendances évolutives de la sous-famille. La phylogénie obtenue indique que la tribu Harttiini forme un groupe paraphylétique et est restreinte à trois genres, et que dans la tribu Loricariini, deux sous-tribus soeurs se distinguent, les Farlowellina et les Loricariina, chacune présentant des patterns évolutifs complexes. Plusieurs nouveaux taxa ont aussi été mis en évidence et décrits. En utilisant la phylogénie comme outil exploratoire, nous avons démontré : (1) avec l’analyse de co-inertie que les caractères diagnostiques fournis pour définir les différents genres étaient sous dépendance phylogénétique ; (2) avec l’analyse de co-inertie multiple que les forces évolutives sous-jacentes dirigeant leur diversification incluaient des composantes intraphénotypiques (morphologie et génétique) et extraphénotypique (écologie et distribution) ; (3) avec l’analyse RLQ que des évènements de co-dispersion entre espèces codistribuées avaient eu lieu et étaient responsables de la distribution actuelle des espèces ; et (4) avec l’analyse de patterns multi-échelles que la co-évolution des traits liés aux caractéristiques de la bouche était liée à des fonctions reproductrices responsables d’une évolution tertiaire de cet organe. / The Loricariinae belong to the Neotropical mailed catfish family Loricariidae, the mostspeciose catfish family in the world, and are united by a long and flattened caudal peduncle and the absence of an adipose fin. Despite numerous works conducted on this group, no phylogeny is presently available. Prior to conduct evolutionary studies, an exhaustive and robust phylogeny was reconstructed using mitochondrial and nuclear data. Then, this phylogeny was used in multivariate and multi-table analyses to reveal the main evolutionary trends of the subfamily. The resulting phylogeny indicated that the Harttiini tribe, as classically defined, formed a paraphyletic assemblage and was restricted to three genera, and within the Loricariini tribe, two sister subtribes were distinguished, Farlowellina and Loricariina, both displaying complex evolutionary patterns. In addition several new taxa were highlighted and described. Subsequently using this phylogeny as exploratory tool, we demonstrated: (1) using co-inertia analysis that the diagnostic features provided to define the different genera were phylogenetically dependent; (2) using multiple co-inertia analysis that the underlying evolutionary forces shaping their diversification included intraphenotypic (morphology and genetics) and extraphenotypic (ecology and distribution) components; (3) using the RLQ analysis that co-dispersion events occurred between co-distributed species responsible for the current fish distribution; and (4) using the multi-scale pattern analysis that the co-evolution in traits related to the mouth characteristics was linked to reproductive functions responsible for a tertiary evolution of this organ.

Orientador: Carlos Roberto Padovani / Banca: Marie Oshiiwa / Banca: Sandra Fiorelli de Almeida Penteado Simeão / Banca: José Carlos Martinez / Banca: Luis Carlos Giarola / Resumo: Objetivou-se a construção de Índices Percentuais de "Status" - IDPS (%) visando à ordenação e classificação de assentamentos rurais, em relação ao desenvolvimento sustentável (IDPSDS (%)), considerando aspectos agronômico, socioeconômico e ambiental, para diagnosticar a realidade dos mesmos. Nesse sentido, consideraram-se procedimentos metodológicos estatísticos analíticos univariados e multivariados para o estabelecimento de descritores analíticos - índices - envolvendo técnicas de Coeficientes de Variação (CV) e Componentes Principais (CP), que foram empregados na construção dos IDPSDS (%). Dados de assentamentos rurais, de sete regiões do Estado de Mato Grosso foram usados na exemplificação da metodologia. A partir de diagnósticos cedidos pela Empresa Mato-Grossense de Pesquisa, Assistência e Extensão Rural S/A - EMPAER-MT, variáveis foram agrupadas em 22 blocos, sendo que seis foram utilizados na construção de índices. As técnicas CP e CV também foram aplicadas em bloco único geral, com 47 variáveis. A variação do Índice Percentual de "Status" (%) - IDPS (%) foi de 0% a 100%. A concordância mínima nos resultados entre as técnicas foi de 6% e máxima de 32%. Os assentamentos com maiores IDPSDS (%) foram considerados de "maior potencial" em relação às variáveis consideradas. A opção de utilização do IDPS (%) pela técnica dos Coeficientes de Variação ou de Componentes Principais é livre e depende exclusivamente do interesse da pesquisa. A fim de comparar os resultados da classificação geral com os grupos formados em função de similaridade do comportamento das variáveis elencadas no bloco único geral, realizou-se o agrupamento dos assentamentos, utilizando-se a técnica de Agrupamento. A classificação e o agrupamento geraram resultados coerentes. O assentamento Vale do Seringal pertencente à região de ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The purpose of this study was the building of Percentage Indexes of "Status" - PIS (%), seeking the ordination and classification of rural settlements, regarding to the sustainable development (Percentages Indexes of Sustainable Development "Status" - PISDS (%)), considering agronomical, socioeconomic and environmental aspects, to diagnose the reality of rural settlements. In this sense, it was took into consideration univariate and multivariate statistical-analytical methodological procedures to the establishment of analytical descriptors - indexes - involving techniques of Variation Coefficients (VC) and Principal Components (PC), which were used in the construction of PISDS (%). Data of rural settlements, from seven regions of the State of Mato Grosso were used in the exemplification of the methodology. By using diagnosis released by the Enterprise of Research, Assistance and Rural Extension from Mato Grosso Inc. - EMPAER- MT, variables were grouped in 22 blocks, 6 blocks of which were used to construct the indexes. The VC and PC techniques were also applied in a unique general block, with 47 variables. The variation of the Percentage Index of "Status" (%) - PIS (%) was from 0% to 100%. The minimum concordance in the results between the techniques was 6% and the maximum, 32%. The settlements with higher PISDS (%) were considered as "higher potential" regarding the considered variables. The option of usage of the PIS (%) by the technique of the Variation Coefficients or the Principal Components is free and depends only on the interest of the research. In order to compare the results of the general classification with the groups formed in function of the similarities in the behavior of the variables listed in the unique general block, the grouping of settlements has been done, using the technique of Grouping. The classification... (Complete abstract click electronic access below) / Doutor

Resumo: A presença de interação genótipo-ambiente é caracterizada pela resposta diferente de genótipos às variações ambientais, e pode ocasionar alteração na classificação de desempenho dos genótipos em diferentes ambientes. Assim é de fundamental importância sua investigação para se obter maior precisão na seleção dos animais. O objetivo deste estudo foi investigar a presença de interação genótipo−ambiente para peso ao sobreano em bovinos da raça Canchim criados no Brasil no período de 1989 a 2000. As metodologias utilizadas foram: 1-comparação de dois modelos: com e sem o efeito não correlacionado touro−ambiente; 2-correlação genética entre o peso ao sobreano em diferentes ambientes; 3-correlação de Pearson e de Spearman entre os valores genéticos dos animais obtidos nos diferentes ambientes, em análises uni e multicaráter; e 4-normas de reação dos animais sobre um gradiente ambiental, obtidas por regressão aleatória. Os ambientes estudados nas metodologias 1, 2 e 3 foram quatro regiões do Brasil (1-Paraná, 2-São Paulo, 3-Minas Gerais e 4- Mato Grosso e Mato Grosso do Sul) e três grupos de municípios do Estado de São Paulo, formados por técnica estatística multivariada para definir grupos de ambientes por meio de variáveis climáticas. Para a metodologia 4, o gradiente ambiental foi obtido por meio das soluções de grupo de contemporâneos. Os modelos utilizados nos métodos 1, 2 e 3 incluíram efeitos fixos de grupo de contemporâneos e de idade ao sobreano como covariável, e os efeitos aleatórios aditivos diretos e residuais. Para o método 4, o modelo incluiu o efeito fixo de idade ao sobreano como covariável, os efeitos aleatórios de grupo de contemporâneos e efeitos genéticos aditivo do intercepto e da inclinação da norma de reação. Os resultados indicaram diferenças nos modelos comparados (com e sem o efeito touro−ambiente)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The genotype-environment interaction presence is characterized by different answers of genotypes to ambient variations, and can cause changes in the classification of the genotypes performances in different environments. The objective in this study was to investigate the presence of genotype - environment interaction for post-yearling weight of Canchim cattle raised in Brazil in the period of 1989 to 2000. The methodologies used were: 1-comparison of two models: with and without the uncorrelated sire−environment effect; 2-genetic correlation between postyearling weight in different environments; 3- Pearson's and Spearman's correlations between animal's breeding values in different environments in one and multitrait analyses; and 4- reaction norms of animals on environmental gradient obtained by random regression. The environments investigated in methods 1, 2 and 3 were four regions of Brazil (1-State of Paraná, 2- State of São Paulo, 3- State of Minas Gerais, and 4- States of Mato Grosso and Mato Grosso do Sul) and three city clusters of the State of São Paulo, formed by multivariate methods to define homogeneous environments of production through climatic variables. For method 4 the environmental gradient was obtained through solutions of contemporary groups. The models used in methods 1, 2 and 3 included fixed effects and random additive direct and residual effects. The model for method 4 included the fixed effect of post-yearling age as covariate, the random effect of contemporary group, and the random additive genetic effecs of intercept and inclination of the reaction norms. The results indicated that differences in the models compared (with and without sire−environment effect), low genetic correlations (0.07 to 0.51) among post-yearling weight in different environments, reclassification of the animals in environments, a scale effect in reaction norms... (Complete abstract click electronic access below) / Orientador: Mauricio Mello de Alencar / Coorientador: Fernando Flores Cardoso / Banca: Joanir Pereira Eler / Banca: Alfredo Ribeiro de Freitas / Banca: Sandra Aidar de Queiroz / Banca: João Ademir de Oliveira / Doutor

Made available in DSpace on 2014-08-20T13:59:08Z (GMT). No. of bitstreams: 1 tese_elisia_rodrigues_correa.pdf: 1900185 bytes, checksum: fcb8093a27a373ee431423cfbdbcb391 (MD5) Previous issue date: 2014-05-21 / Improving the yield is the primary aim for the macadamia breeding program, together with it the breeder has the constant challenge of trying to add others traits which will promote macadamia value. Among these stands out the study of pollination character, a factor that brings benefits to the production, since plants with this feature are independent of pollinating vectors, which are currently declining in population. Along with this feature is the search for a product (nut) with a nutritional value which will bring a beneficial to human health, for macadamia the goal is the development of oil with a good rate of monounsaturated fats. Faced with these challenges, the objective was to identify genotypes with greater production of nuts and to provide a high rate of self-pollination, as well to establish strategies to better characterize the profile of macadamia nut oils. For the self-fertility experiment, racemes from cultivated and wild macadamia tree were tagged and bagged for comparing self-pollination and open pollination. T1002.003, T108.002 and T1023.003 were the only wild genotypes which presents Final Nut Set from self-pollination. In the oil studies, three experiments were carried out. The first aiming to quantify the sample size of macadamia nuts for best characterizes the fatty acids oil profile. Macadamia nuts were harvested, dried, the oil were extracted and after analyzed with gas chromatography. The variance found among the nuts from the same tree is bigger than the variance among the genotypes conducting to the second experiment, aiming to understand the possible source of variability at macadamia oil profile and the better way for controlling it, twenty nuts from four tree of macadamia cultivar, A16, were harvested. However the variance among the nuts was not controlled too. A third experiment was developed for checking if it has a pollen influence at fatty acids profile in the macadamia oil. Nuts from the selection 11.1 from three source of pollen (open pollination, self-pollination and a cross with the genotype 268) were harvested. Overall, the result from the experiments shows that the pollen has an influence in the oil profile. The aim of the last experiment was to identify the best genotypes in a population of macadamia plants in relation to annual production of almonds, aimed establishing a base population for a breeding. The results obtained by mixed model methodology (REML / BLUP) and the correlation between genotype and phenotype demonstrate the importance of using BLUP predictors as a tool for breeding programs related to this case study. / Aliado a busca por plantas de macadâmia mais produtivas, o pesquisador possui o desafio constante de tentar associar outras características as quais possam agregar valor a noz e assessorar os mais variados aspectos da produção. Dentre estes se destaca o estudo do caractere polinização, considerando que a autopolinização beneficia a produção, uma vez que plantas com esta característica independem de vetores polinizadores, que estão em declínio populacional atualmente. Junto a essa característica é incessante a busca por um produto (noz) com maior valor nutricional à saúde humana, no caso da macadâmia, um óleo com boa taxa de gorduras monoinsaturadas. Frente a estes desafios o objetivo do trabalho foi de identificar genótipos com maior produção de nozes e que apresentassem alta taxa de autopolinização, além de estabelecer estratégias para melhor a caracterização do perfil dos óleos de macadâmia para a inserção do estudo da composição dos óleos no melhoramento de macadâmia. Para o experimento de autopolinização, racemos florais de cultivares e matérias nativos foram ensacados e acompanhados quanto ao desenvolvimento da noz. Outros racemos florais foram apenas identificados e acompanhados para posterior comparação da polinização aberta em relação a autopolinizada. Três genótipos oriundos do grupo da macadâmia nativa apresentaram autopolinização. Nos estudos com óleo, três ensaios foram conduzidos. O primeiro com o intuito de quantificar o tamanho da amostra de macadâmia para a melhor representatividade referente ao perfil do óleo. Foram colhidas nozes de quatro cultivares, duas plantas por cultivar e vinte nozes por planta. As nozes foram secas e o perfil do óleo extraído determinado por cromatografia gasosa. A variância encontrada entre as nozes provenientes da mesma planta foi maior do que entre os genótipos, conduzindo assim ao objetivo do segundo ensaio. Com o intuito de identificar se o estádio de desenvolvimento da noz interfere no perfil do óleo, vinte nozes de quatro plantas da cultivar A16 foram colhidas e avaliadas. No entanto, como a causa potencial do alto nível de variabilidade é desconhecido ou não pode ser explorada, acredita-se que única outra opção é trabalhar com um grande número de nozes. O terceiro ensaio desenvolvido dentro do âmbito do perfil do óleo foi o da influência da fonte do pólen. Nozes da seleção 11.1 oriundas de três fontes de pólen (polinização aberta, autopolinização, e cruzamento com o genótipo 268) foram colhidas. Foi verificado que a fonte do pólen influencia no perfil do óleo. O objetivo do último experimento foi identificar os melhores genótipos em uma população de plantas de macadâmia, com relação à produção anual de amêndoas, visando estabelecer uma população base para programa de melhoramento e aprimorar a propagação vegetativa no sistema de produção. Os resultados obtidos pela metodologia de modelos mistos (REML/BLUP) e a correlação entre genótipo e fenótipo demonstram a importância do uso de preditores BLUP como ferramenta para programas de melhoramento relacionados a este estudo de caso.

The Florida Reef Tract (FRT) extends from the tropical Caribbean up the southeast coast of Florida into a temperate environment where tropical reef assemblages diminish with increasing latitude. This study used data from a three-year comprehensive fishery-independent survey to quantify reef fish spatial distribution along the Southeast FRT and define where the assemblage shifts from tropical to temperate. A total of 1,676 reef fish visual census samples were conducted to assess the populations on a stratified-random selection of sites of marine hardbottom habitats between the Miami River and St. Lucie inlet. Multivariate analyses were used to investigate differences in assemblages among sites. Depth (m), general habitat (reef or hardbottom), and slope (high or low) strata were examined to explain the dissimilarities between assemblages. A general trend of cold-tolerant temperate fish dominated the northern assemblages and more tropical species dominated further south. Seven reef fish assemblage biogeographic regions were determined. In shallow habitats the data clustered in three spatial regions: One south of Hillsboro inlet, one in Northern Palm Beach south of Lake Worth inlet, and one north of Lake Worth inlet. The assemblage in deep habitats mainly split in close proximity to the Bahamas Fracture Zone south of Lake Worth Inlet. The presence of reef habitat aided in splitting the southern assemblage regions from the northern all-hardbottom assemblage regions in both the shallow and deep habitats. Substrate relief was significantly correlated with the differences in the northernmost deep assemblages but did not appear to affect the remainder of the shallow and deep assemblages. This bioregional study creates a baseline assessment of reef fish assemblages of the Southeast FRT for future analyses.

Les estuaires font partie des écosystèmes les plus productifs de la planète. Ils constituent une zone d'importants échanges de matières et jouent à ce titre un rôle capital pour les cycles biogéochimiques. Du fait de leur position à l'interface entre domaines continental et marin, ils sont également un lieu de passage obligatoire pour de nombreuses espèces de poissons migrateurs ou encore de nourricerie et de refuge. Ces systèmes sont contraints par de nombreuses pressions de natures diverses dont certaines en lien avec les activités humaines locales (p. ex. pêcheries, transport maritime, dragages, pollutions accrues, etc.). Ces altérations viennent s'ajouter à la variabilité intrinsèque de ces systèmes naturellement complexes (variabilité spatio-temporelle de différents facteurs environnementaux ; c.-à-d. température, salinité, turbidité, etc.). Toutefois, une intensification de ces d'altérations, dont une partie est associée à la composante climatique des changements globaux, est observée depuis ces dernières décennies. Ces modifications avérées et leurs incidences sur les communautés biologiques constituent un enjeu en matière de gestion des écosystèmes estuariens. Cependant, par manque de chroniques de données continues suffisamment longues, peu d'études sur l’évolution à long terme de systèmes estuariens ont été réalisées à ce jour. Pour mes travaux, j'ai eu à ma disposition un ensemble de chroniques uniques - acquises depuis 35 ans - associées à plusieurs suivis écologiques de l'estuaire de la Gironde (notre site atelier). L'objectif général de cette thèse est de caractériser l’évolution globale du système dans son ensemble (physico-chimie et biologie) et d'identifier les forçages impliqués. L’originalité de ces travaux, par rapport aux études spécifiques déjà menées, consiste à analyser l’évolution de l’ensemble des descripteurs caractéristiques du fonctionnement d'un système modèle et de qualifier la part relative aux forçages globaux. L'étude des séries chronologiques, via une approche end-to-end basée sur des analyses multivariées, permet d'identifier deux changements abrupts d'état de l'écosystème de l'estuaire de la Gironde, associés à des fluctuations hydroclimatiques à large échelle (bassin Atlantique nord) mais aussi à une échelle plus locale (estuaire). Des hypothèses relatives aux possibles mécanismes impliqués, reliant les altérations climatiques à large échelle aux altérations observées à l'échelle des communautés biologiques estuariennes, sont discutées. Un deuxième volet de la thèse, au travers d’une approche modélisatrice basée sur le concept de niche d'Hutchinson, permet d'identifier un changement de répartition spatiale, longitudinale, des populations de copépodes estuariennes en réponse au réchauffement des masses d'eau et à la marinisation de l'estuaire. Enfin un troisième volet de mes travaux s'est consacré à l'étude spécifique d'une espèce de copépode invasive : Acartia tonsa. Suivant une double approche modélisatrice permettant d'estimer à la fois les niches fondamentale et réalisée de l'espèce, ces travaux illustrent l'importance relative des changements climatiques qui ont facilité la colonisation et l'essor de cette espèce dans l'estuaire. / Estuaries are among the most productive ecosystems on Earth. They constitute important areas for materials exchanges and play therefore a crucial part in biogeochemical cycles. Because of their location at the interface between marine and continental realms, they are also a migratory path for different fish species and in some cases, a nursery or a refuge area. These systems are submitted to many pressures, some of them being related to anthropogenic activities (e.g fisheries, maritime traffic, dredging, rising pollutions, etc.). These changes are superimposed to the intrinsic variability of these naturally complex ecosystems (characterized by a spatio-temporal variability of different environmental factors; i.e., temperature, salinity, turbidity, etc.). However, since recent years, an intensification of these alterations, being partly linked to the climatic component of Global Change, is observed. These changes, already documented, and their incidence on biological communities, constitute a challenge for the future management of estuarine ecosystems. However, due to a lack of long-term continuous time series, for now few studies on the long-term evolutions of estuarine systems have been reported. In this work, I used a unique set of data (35 years) provided by an ecological monitoring of the Gironde estuary (the model of estuary used in the study). The main objective of this thesis is to characterize the evolution of the whole system (physico-chemistry and biology) over the last three decades and to identify the forcings involved. The originality of this work comes from a global analysis of the main estuarine descriptors and from the evaluation of the relative contribution of global forcings. A study based on multivariate analyses, through an end-to-end approach, reveals two abrupt shifts in the state of the ecosystem of the Gironde estuary. These two changes appear to be linked to hydroclimatic fluctuations at a regional scale (North Atlantic basin) and also at a local scale. Some hypotheses on the possible mechanisms involved, linking the large-scale climatic alterations to the changes observed on the biological estuarine communities are discussed. A second study that uses a modeling approach based on the ecological niche concept of Hutchinson, identifies a change in the spatial (longitudinal) distribution of estuarine copepod populations in response to warming and marinisation processes. Finally, a third work focuses on an invasive copepod species: Acartia tonsa. A double modeling approach estimates both the fundamental and realized niches of the species. The results highlight the relative importance of climate changes that facilitated the colonization of the estuary by A. tonsa.

La compréhension des processus écologiques qui sous-tendent l’assemblage des communautés végétales et la coexistence des espèces est un objectif central en écologie. Ces processus sont potentiellement nombreux et de natures contrastées. Ainsi, la composition d’une communauté de plantes dépend de processus déterministes liés aux conditions environnementales abiotiques (climat, conditions physiques et chimiques du sol, lumière) et d’interactions biotiques complexes, positives (facilitation, symbioses) comme négatives (compétition, prédation, pathogènes). En outre, les communautés sont influencées par des processus stochastiques (capacité de dispersion limitée, dérive écologique). Si les mécanismes à l’origine de ces processus sont très différents, ils ont néanmoins en commun la génération de motifs (patterns) spatiaux de distribution d’espèces dans les communautés. L’analyse de la structure spatiale des communautés permet ainsi une étude indirecte des processus régissant les communautés. La nature complexe de ces patterns spatiaux a mené au développement de nombreuses méthodes statistiques de détection et de description de patterns. Les méthodes basées sur des vecteurs propres spatiaux sont parmi les plus puissantes et précises pour détecter des patterns complexes et multi-échelles. Ces vecteurs propres, utilisés comme prédicteurs spatiaux, peuvent être combinés à un ensemble de variables environnementales dans un cadre de partition de variation. Celui-ci permet, en théorie, de démêler les effets uniques et l’effet conjoint des variables environnementales et spatiales sur la variation de composition d’une communauté. Il mène ainsi à une quantification de l’action des processus déterministes et des processus stochastiques sur l’assemblage de la communauté. Néanmoins, je montre dans cette thèse qu’un certain flou méthodologique concernant deux étapes déterminantes des analyses basées sur les vecteurs propres spatiaux a mené une proportion élevée d’études à utiliser ces méthodes de manière sous-optimale, voire fortement biaisée. Ceci compromet la fiabilité des patterns spatiaux détectés et des processus écologiques inférés. Une autre limitation de ce cadre d’analyse concerne la fraction de la partition de variation décrivant l’effet environnemental spatialement structurés qu’aucune méthode ne permet de tester.Cette thèse présente des solutions non biaisées, puissantes et précises à ces différentes limitations méthodologiques et permet d’élargir le cadre de l’inférence de processus écologique à partir de patterns spatiaux de communautés. Les différentes étapes d’amélioration de ces méthodes ont également été illustrées dans la thèse au travers de trois cas d’études fournis par deux communautés d’arbres tropicale et tempérée et une communauté de champignons symbiotiques des arbres. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Les distributions d'espèces observées dans un environnement hétérogène résultent de plusieurs processus déterministes et stochastiques agissant comme des filtres pour contraindre la coexistence des espèces. L’action successive de ces processus a pour conséquence directe de structurer spatialement la composition des communautés et la variation de ces compositions (i.e., diversité bêta). Un des objectifs majeurs de l'écologie des communautés et métacommunautés consiste à identifier et quantifier les effets respectifs de ces différents processus sur la diversité bêta des communautés afin de mieux comprendre et prédire la distribution de la biodiversité. L'expérimentation étant difficilement possible, les processus responsables de la variation spatiale de la composition des communautés sont généralement inférés à partir des structures spatiales des distributions d’espèces observées dans la nature. La thèse s’inscrit dans ce contexte et vise à améliorer les outils de statistique multivariée permettant d’identifier et quantifier l'effet des processus écologiques structurant les communautés et métacommunautés. En particulier, il est proposé d’intégrer les échelles écologiques et les modèles nuls contraints pour étudier l’effet de l’environnement. La décomposition des relations trait-environnement dans les échelles spatiales et phylogénétiques permet une étude plus approfondie du filtrage environnemental en associant son échelle spatiale d’action au signal phylogénétique des traits sélectionnés pour capturer l’histoire évolutive associée au filtrage environnemental. L’interprétation en terme de processus évolutifs est néanmoins limitée et mériterait l’intégration de modèles nuls phylogénétiquement contraints pour une analyse plus fine. Dans la continuité, des modèles nuls spatialement contrains ont été développés et intégrés à deux analyses multivariées très largement utilisées en écologie des communautés (i.e., partitionnement de variation et test de Mantel) pour estimer et tester l’effet de l’environnement sur les assemblages d’espèces. Ces deux analyses présentaient une surestimation de leur statistique mesurée ainsi qu’un taux anormal de faux positifs lorsque les distributions d’espèces (via processus de dispersion limitée) et l’environnement étaient indépendamment spatialement structurés. L’intégration de modèles nuls spatialement contraints a permis d’ajuster à la fois les estimations et les tests de ces deux analyses illustrant ainsi le besoin d’utiliser des modèles nuls écologiquement contraints pour une identification et quantification correctes des processus écologiques / Species distributions observed in an heterogeneous environment result from multiple deterministic and stochastic processes acting as filters to constrain species co-existence. As a direct consequence, the successive actions of these processes spatially structure communities composition and the variation of these compositions (i.e., beta-diversity). One of the major objective in community and metacommunity ecology is to identify and quantify the respective effects of these different processes on communities beta-diversity to better understand and predict the distribution of biodiversity. Experiments being hardly possible, processes responsible for the spatial variation of communities composition are generally inferred from spatial patterns of species distributions observed in nature. In this context, the thesis aims at improving multivariate statistical tools conducted to identify and quantify the effects of ecological processes shaping communities and metacommunities. In particular, this thesis proposes to integrate ecological scales and constrained null models to study the effect of environment.Decomposing trait-environment relationships through spatial and phylogenetic scales allows to further study environmental filtering. The association of spatial scales involved in environmental filtering with the phylogenetic signals of traits allowed to capture the evolutive history related to environmental filtering. The interpretation in terms of evolutive processes is however limited and phylogenetically-constrained null models should be considered to improve the analysis. Following on from this work, spatially-constrained null models were developed and integrated into two multivariate analyses widely used in community ecology (i.e., variation partitioning and Mantel tests) to estimate and test the effect of environmental filtering on species assemblages. Both approaches presented overestimation of their computed statistic as well as high rates of false positive when species distributions (via limited dispersal) and environmental conditions were independently spatially structured. Integrating spatially-constrained null models allowed to adjust both their tests and the values of their statistic, as such demonstrating the need of using ecologically-constrained null models to correctly identify and quantify ecological processes.For future works, the thesis suggests that adopting a scaling approach to study ecological processes in addition to mechanistic null models could offer the possibility to distinguish processes from one another