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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Vztah biodiverzity a produktivity ve společenstvech krásivek / Biodiversity-productivity relationship in desmid communities

Škvorová, Marie January 2019 (has links)
This thesis deals with biodiversity-productivity relationship in desmid communities. Biodiversity is found to be changing globally. The biodiversity-productivity relationship is therefore an important research topic. Three aspects of biodiversity are thought to play an important role: species richness, functional diversity and phylogenetic diversity. It is known that in general, productivity is positively correlated with diversity. Interactions between different metrics of biodiversity are known less. Existing studies have shown that these interactions might be present. In general, biodiversity-productivity studies were mostly focused on plants. Less is known about other organisms, including algae. In this work I explore the relationship between overyielding and functional or phylogenetic diversity on a species richness gradient of desmid communities. I conducted an artificial biodiversity- ecosystem functioning experiment using combinations of two to 12 desmid species. Communities differed in the diversity aspects. I had measured the biomass growth. For the analysis, I have used the overyielding index, which is based on a comparison of a polyculture production with the production expected based on monoculture yields. The relationship of overyielding on functional diversity depended on species...
32

Identifier les arbres du Québec grâce à la spectroscopie foliaire : différenciation fonctionnelle et phylogénétique des espèces

Blanchard, Florence 04 1900 (has links)
La spectroscopie représente un puissant outil en conservation grâce à la possibilité d’effectuer le suivi de la diversité végétale à travers de larges étendues géographiques. La réflectance spectrale montre un potentiel certain pour l’identification des espèces d’arbres et même des taxons inférieurs, mais ceci a rarement été testé sur un grand nombre d’espèces. J’examine la qualité de la classification de 45 espèces d’arbres des forêts tempérées du Québec à partir de plus de 3500 spectres de réflectance foliaires (400-2400 nm). Nous évaluons cette classification sur la base de la variation spectrale des espèces, de même qu’à partir des distances fonctionnelles et phylogénétiques mesurées. Nos résultats indiquent un taux de classification très satisfaisant (κ = 0.736, ±0.005). Nous observons des erreurs de classification plus fréquentes entre les espèces évolutivement proches, alors qu’il semble que la distance fonctionnelle établisse un seuil voulant qu'au-delà d’une certaine distinction fonctionnelle globale, il soit peu probable que deux espèces soient confondues. Ces résultats viennent renforcer le lien entre la diversité spectrale et l’organisation taxonomique des espèces, ajoutant à la valeur de substitution de la première pour la diversité phylogénétique. Cela suggère par contre que de fortes convergences fonctionnelles peuvent faire obstacle à l’identification des espèces à partir de la réflectance spectrale. Cette étude est prometteuse pour la classification de spectres foliaires non préalablement identifiés, et améliore notre compréhension du lien entre les données spectrales et la différenciation des espèces, d’une grande importance pour assurer la validité des estimations de la biodiversité à partir de données de télédétection. / Imaging Spectroscopy is a powerful tool for conservation due to its ability to monitor plant diversity over broad geographic areas. Increasing evidence suggests that spectral reflectance can be used to identify trees at the species level, and even below. However, most studies focus on only a few species. Here, we use foliar reflectance (400-2400 nm) to discriminate among 45 temperate forest tree species from southern Quebec, using over 3500 leaf-level spectra. Furthermore, we connect those classification results to functional and phylogenetic distinctiveness, as well as to intraspecific variation. We find that spectral reflectance shows a very good discriminatory power even with an extensive set of species (κ = 0.736, ±0.005). We find that close phylogenetic species get mistaken for one another more frequently than distantly related species, while functional variation acts as a threshold, beyond which misclassifications are unlikely. These results reinforce the link between spectral diversity and taxonomic organization or phylogenetic diversity, but also reiterate the potential confounding effects of functional convergences on species identification from hyperspectral reflectance. We believe these findings hold promise for the classification of unknown spectra and further improve the link between ground truth and remotely sensed data for biodiversity assessments.
33

Structure et dynamique de la communauté bactérienne libre et attachée dans les écosystèmes lacustres

Parveen, Bushra 25 January 2012 (has links)
C'est essentiellement sur les bactéries libres que portent les études récentes en écologie microbienne d'eau douce, et seulement quelques études ont concerné les communautés bactériennes attachées. Dans cette étude basée sur l'analyse des séquences du gène 16SARNr, la diversité des communautés bactériennes attachées ainsi que de la fraction libre a été étudiée sur deux systèmes d'eau douce ; un lac mésotrophe (le lac du Bourget) et un lac hypereutrophe (le lac Villerest). La diversité des Actinobacteria, Betaproteobacteria et Verrucomicrobia libres et attachées a été étudié en relation avec les variables environnementales, dans le lac du Bourget pendant deux périodes à dominances contrastées de phytoplancton. L'analyse des résultats a montré une différence au niveau phylogénétique entre les communautés bactériennes attachées et libres des trois groupes de bactéries étudiées. Le clade betaI, dominait les Betaproteobacteria des fractions libres et attachées, avec 57,8% de la totalité des unités taxinomiques opérationnelles (OTUs). Pour les Actinobacteria, le groupe d'acIV a été détecté comme le plus abondant, suivi par acI avec respectivement 45% et 25% du total des OTUs. De même, les groupes Verrucomicrobia d'eau douce, à savoir CREPA29, FukuN18, CL120-10 sont apparus comme les plus importants, avec 22,3%, 16,15% et 14,61% des OTUs respectivement. Cette étude a permis de définir 15 nouveaux clades putatifs représentant la diversité bactérienne d'eau douce des Betaproteobacteria (lbI-lbVIII), Actinobacteria (acLBI) et Verrucomicrobia (CRE-PA29, FukuS27, BourFI-BourFIV). Par ailleurs, 12 groupes représentant la diversité de phylogénétique des Betaproteobacteria, Actinobacteria et Verrucomicrobia contiennent exclusivement des OTUs de la fraction attachée. La dynamique saisonnière souligne les changements des phylotypes bactériens distincts pour les deux communautés attaché et libre. Les Actinobacteria dans la fraction attachée était associée avec la biomasse des Chrysophyceae et N-NO3, et les Betaproteobacteria avec la biomasse de Chlorophyceae et de la richesse du phytoplancton tandis que les Verrucomicrobia de cette même fraction ont semblé être principalement influencés par la richesse du phytoplancton, l′abondance des rotifères et les nutriments inorganiques (N-NO3, SiO2). D'autre part, dans les communautés libres, peu de clades d'actinobacterie dépendent des nutriments ou du phytoplancton, alors que les Betaproteobacteria et Verrucomicrobia ont été principalement associés avec les paramètres biologiques (i.e. phytoplancton et copépodes). Pendant le bloom des cyanobacteries (Microcystis sp.) dans le lac Villerest, les Betaproteobacteria, Gammaproteobacteria, Alphaproteobacteria, Bacteroidetes et Actinobacteria ont été détectés comme taxa dominants dans les banques de clones du gène 16S ARNr. Toutefois Verrucomicrobia et Deinococcus-Thermus sont apparus relativement moins abondants dans les deux fractions, tandis que,Gemmatimonadetes, Acidobacteria, Chloroflexi, Planctomycetes, Deltaproteobacteria, Firmicutes et Op11 sont apparus comme des phyla mineurs dans la banque de clones des communautés bactériennes attaché et libre. Les Betaproteobacteria (n=118) attachées sont apparus comme le groupe dominant, suivi par Gammaproteobacteria (n=74) et Bacteroidetes (n=52). L'analyse phylogénétique des séquences obtenues pour la banque de clone de la fraction libre a montré que la plupart des OTUs appartiennent à Betaproteobacteria (n=192), suivi par Bacteroidetes (n=132) et Actinobacteria (n=61). Tandis que les Gammaproteobacteria (n=42) et Alphaproteobacteria (n=42) sont présents dans des proportions égales dans la banque de clones du 16S ARNr libre. (...) / The free-living bacteria point of view dominates in recent research of freshwater microbial ecology, only a few studies have focused on attached bacterial communities. In present study, based on 16S rRNA gene sequences, diversity of attached and free-living bacterial community was investigated from two freshwater aquatic systems ; a mesotrophic lake Bourget and a hypereutrophic lake Villerest. The diversity of attached and free-living Actinobacteria, Betaproteobacteria and Verrucomicrobia, in relation to environmental variables was investigated from lake Bourget during two contrasting periods of phytoplankton dominance. Comparison analyses showed a phylogenetic difference between attached and free-living bacterial communities of all three studied bacterial groups. The betaI, appeared as most dominant among all clades representing phylogenetic diversity of freshwater Betaproteobacteria, for both attached and free-living fractions, contributing to 57.8% of of the total retrieved opertational taxonomic units (OTUs). For Actinobacteria, the acIV cluster was detected as dominant, followed by acI accounting for 45% and 25% of the total retrieved OTUs respectively. Similarly, freshwater Verrucomicrobia cluster namely, CRE-PA29, FukuN18, CL120-10 appeared as dominant, comprising 22.3%, 16.15% and 14.61% of the total retrieved OTUs respectively. This study allowed defining 15 new putative clades representing the freshwater bacterial divesity of Betaproteobacteria (lbI-lbVIII), Actinobacteria (acLBI) and Verrucomicrobia (CRE-PA29, FukuS27, BourFI-BourFIV). In addition, 12 clusters representing the phylogenetic diversity of Betaproteobacteria, Actinobacteria and Verrucomicrobia were exclusively comprised of OTUs from the attached fraction. The seasonal dynamics of environmental variables have been reflected as changes in distinct bacterial phylotypes for both attached and free-living communities. The attached bacterial communities of Actinobacteria showed affiliation with Chrysophyceae biomass and N-NO3, while attached Betaproteobacteria were affiliated with biomass of Chlorophyceae and phytoplankton richness. Similarly attached verrucomicrobial communities appeared to be mainly influenced by phytoplankton richness, rotifers abundances and inorganic nutrients (NNO3,SiO2). On the other hand, within free-living communities, few actinobacterial clades were found to be dependent on either nutrients or phytoplankton communities, whereas Betaproteobacteria and Verrucomicrobia were mainly associated with biological parameters (i.e. phytoplankton and copepods communities). In another study during a cyanobacterial (Microcystis sp.) bloom from lake Villerest, Betaproteobacteria, Gammaproteobacteria, Alphaproteobacteria, Bacteroidetes and Actinobacteria were detected as prevalent taxa among the 16S rRNA gene clone libraries, however, Verrucomicrobia and Deinococcus-Thermus appeared as comparatively less abundant bacterial groups in both fractions. Whereas, Gemmatimonadetes, Acidobacteria, Chloroflexi, Planctomycetes, Deltaproteobacteria, Firmicutes and Op11 were appeared as minor phyla in clone libraries of attached and free-living bacterial communities. For attached bacterial communities Betaproteobacteria (n=118) appeared as most dominant group, followed by Gammaproteobacteria (n=74) and Bacteroidetes (n=52). The phylogenetic analysis of the sequences obtained for the clone library from free-living fraction showed that most of the OTUs belonged to Betaproteobacteria (n=192) followed in decreasing order by Bacteroidetes (n=132) and Actinobacteria (n=61) whereas Gammaproteobacteria (n=42) and Alphaproteobacteria (n=42) appeared in equal proportion in free-living 16S rRNA clone libraries. (...)
34

Assessment of the functional diversity of soil microbial communities in the German Biodiversity Exploratories by metagenomics / Erschließung der funktionellen Diversität mikrobieller Bodengemeinschaften in den deutschen Biodiversitäts-Exploratorien durch Metagenomik

Will, Christiane 28 January 2011 (has links)
No description available.
35

Réponses des communautés piscicoles aux changements globaux : patrons et processus / Freshwater fish communities facing global changes : patterns and processes

Kuczynski, Lucie 15 December 2017 (has links)
La description des gradients spatiaux ainsi que la documentation des dynamiques temporelles de la biodiversité sont des piliers centraux de l'écologie moderne, en particulier dans le contexte actuel des changements globaux auquel l'intérêt porté est croissant depuis les dernières décennies. Les communautés écologiques sont désormais reconnues comme des entités issues de la sélection d'espèces à partir d'un pool régional, sélection déterminée par différents processus appelés règles d'assemblage. Les deux règles d'assemblage principalement reconnues sont les filtres environnementaux, sélectionnant des espèces similaires adaptées à un milieu, et la limite à la ressemblance, sélectionnant des espèces dont les caractéristiques n'induisent pas de compétition trop forte et permettent la coexistence. Les objectifs de ma thèse ont été de (i) comprendre les patrons spatiaux de la diversité des communautés piscicoles à large échelle, (ii) comprendre la dynamique temporelle de cette diversité et (iii) d'appréhender la dynamique temporelle des processus sous-jacents à la structuration des communautés. Pour ce faire, des données de communautés piscicoles ont été analysées, d'une part à l'échelle continentale (i.e. européenne), et d'autre part à l'échelle nationale (i.e. France) pour laquelle la dimension temporelle est également disponible (i.e. séries temporelles depuis 1966 jusqu'à 2012). La description de la diversité piscicole européenne a permis de mettre en évidence la complémentarité des facettes phylogénétique, morphologique et écologique de la diversité. De plus, le climat, et en particulier la saisonnalité des conditions climatiques, est apparu comme un déterminant majeur de la distribution spatiale de la diversité. A une échelle plus locale et en tenant compte de la temporalité des communautés, il a été mis en évidence que les communautés piscicoles françaises connaissaient actuellement une réorganisation taxonomique due aux déclins de populations et menant à une homogénéisation taxonomique globale. Bien qu'une réorganisation fonctionnelle de ces mêmes communautés ait été observée, résultant des variations démographiques des espèces d'eau chaude et de bas niveau trophique, les conséquences à large échelle restent à explorer. De plus, depuis les années 90, les filtres environnementaux se sont renforcés dans leur rôle structurant des communautés. Finalement, les travaux de cette thèse ont permis de valider des hypothèses usuellement associées aux patrons spatiaux de la diversité, comme mécanismes en lien avec les variations temporelles de la diversité. L'hypothèse de prédominance du stress (au travers des changements de saisonnalités des températures) et de préadaptation des espèces non-natives ont notamment permis de comprendre les dynamiques temporelles de diversité ainsi que des règles d'assemblage sous-jacentes à la structuration des communautés. / The description of spatial patterns as well as temporal dynamics of diversity has been a major cornerstone in modern ecology, especially in the contemporary context of global changes for which a growing concern is notable during last decades. Ecological communities are now acknowledged as the result of species that are sorted by selection from the regional pool. This selection of species is determined by several processes, namely the assembly rules. The two main assembly rules are the habitat filtering, selecting species that are able to inhabit in a given set of abiotic conditions, and the limiting similarity, selecting species for which ecological features are dissimilar in order to avoid a too strong competition and to coexist. The goals of my thesis were to (i) understand spatial patterns of freshwater fish community diversity at large scale, (ii) understand temporal dynamic of this diversity and (iii) describe temporal dynamics of the processes underlying the structuration of communities. In order to do this, data of freshwater fish communities has been analyzed first at continental scale (i.e. European) and then at national scale (i.e. France) for which temporal dimension of the data was also available (time series from 1966 to 2012). Based on the European freshwater diversity, we highlighted that phylogenetic, morphological and ecological facets were complementary. Moreover, climatic conditions, and especially their seasonality, seem to be a major driver of the spatial distribution of diversity. At finer scale and by taking into account the temporality of communities, we found that French freshwater communities experienced taxonomic reorganization due to population declines that ultimately leads to taxonomic homogenization of freshwater diversity in France. Although functional homogenization has been observed due to demographic fluctuations of warm water-dweller and low trophic level species, consequences at large scale remained to be explored. Moreover, since the 90s, habitat filtering increased as structuring force for freshwater fish communities. Finally, this thesis allowed us to validate hypothesis usually associated to spatial patterns of diversity, as mechanisms related to temporal variations of diversity. The stress dominance hypothesis (through temporal trends in temperature seasonality) and preadaption hypothesis (related to non-native species) have been used to understand temporal dynamics of diversity as well as of the assembly rules underlying structuration of communities.
36

Efeito de pertubações antrópicas crônicas sobre a diversidade da flora lenhosa da caatinga

RIBEIRO, Elâine Maria dos Santos 25 February 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-15T14:44:30Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Elâine_Ribeiro_TESE_PPGBV.final_V2.pdf: 8805946 bytes, checksum: 49c5072b57c8b0d0264ac0e02e425dc3 (MD5) / Made available in DSpace on 2016-07-15T14:44:30Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Elâine_Ribeiro_TESE_PPGBV.final_V2.pdf: 8805946 bytes, checksum: 49c5072b57c8b0d0264ac0e02e425dc3 (MD5) Previous issue date: 2015-02-25 / FACEPE / Este estudo teve como objetivo investigar quais os efeitos de perturbações antrópicas crônicas (e.g. coleta de madeira e de produtos florestais não madeireiros, pastoreio extensivo, caça e danos causados à vegetação pela introdução de espécies exóticas que ocorrem em áreas remanescentes de floresta) sobre a diversidade taxonômica e filogenética da flora lenhosa da Caatinga. Inicialmente, investigamos como se dá a questão da perturbação crônica da flora e seus efeitos sobre a biodiversidade através da revisão de 51 artigos que tratam do tema. Verificamos que estes estudos, em sua maioria, foram realizados em países em desenvolvimento, cujas populações humanas utilizam a floresta para subsistência e comércio. Os efeitos da perturbação foram acessados principalmente ao nível de populações e comunidades, sendo a coleta de produtos florestais não madeireiros a fonte de impacto mais analisada. Os efeitos sobre a biodiversidade foram em geral negativos, mas efeitos neutros e positivos também foram registrados. O segundo capítulo traz um estudo de caso que verifica a influência das perturbações humanas crônicas sobre a diversidade e composição taxonômica da flora lenhosa da Caatinga, realizado em várias propriedades privadas na cidade de Parnamirim-PE, Brasil. Neste estudo foram amostradas comunidades lenhosas de adultos, jovens e plântulas, e como preditores da perturbação crônica utilizaram-se a densidade de pessoas e animais domésticos (caprinos e bovinos), além de indicadores de acessibilidade às áreas, como a distância ao centro urbano mais próximo, à estrada mais próxima e à propriedade rural mais próxima às parcelas amostradas. Esses preditores tiveram em geral efeitos negativos sobre a diversidade taxonômica independente do estágio ontogenético, sendo a densidade de pessoas e de animais os preditores mais importantes desses efeitos. Verificouse ainda que a composição das espécies nas áreas perturbadas foi distinta, sendo pouco representada pela abundância de espécies de madeira densa nas áreas mais perturbadas. O terceiro e último capítulo verificou como as comunidades lenhosas de adultos, jovens e plântulas da Caatinga, amostradas no capítulo anterior, são afetadas pela perturbação crônica do ponto de vista de diversidade e estrutura filogenética. Neste capítulo, utilizaram-se os mesmos preditores da perturbação citados anteriormente, porém agora combinados em um índice de perturbação crônica. A diversidade de famílias esperadas para história evolutiva da região e a distância média entre os indivíduos dessas comunidades, medida em anos, foi reduzida em ambientes mais perturbados e para todos os estágios ontogenéticos. As comunidades de jovens e de plântulas apresentaram maior grau de parentesco em áreas mais perturbadas, sendo os táxons Euphorbiaceae e Cnidoscolus responsáveis por esse aumento de parentesco. Os resultados desta tese demonstram que as perturbações antrópicas crônicas na Caatinga não podem ser negligenciadas, pois conferem efeitos negativos importantes à diversidade taxonômica e filogenética da flora lenhosa. Dessa forma, estratégias de manejo que conciliem o uso dessas florestas e a manutenção da biodiversidade da Caatinga são urgentes. / The aim of this study was to investigate the effect of chronic anthropogenic disturbances (e.g. harvesting of timber and non-timber forest products, hunting, livestock, and damage to vegetation caused by exotic species that occur in natural remnant forests) on the taxonomic and phylogenetic diversity of wood flora from Brazilian Caatinga. Initially, 51 scientific papers were revised in order to investigate how chronic anthropogenic disturbances affect the flora of natural ecosystems. Most studies were conducted at developing countries, where human populations use forest resources for subsistence and commerce. Chronic disturbance effects were accessed mainly at population and community levels, and harvesting of nontimber forest products was the disturbance source more frequently analyzed in those papers. Effects of the chronic disturbances were in general negative, however positive and neutral effects were also documented. The second chapter brings a case study that evaluates the influence of chronic disturbances on the taxonomic diversity and composition of Caatinga wood flora from private propreties at the municipality of Parnamirim-PE, Brazil. Adult, sapling and seedling of wood plant communities were sampled, and the density of people and livestock (goats and catle) near the plot were used as predictors of chronic disturbance, as well as the distances to the nearest urban centre, road and rural property. In general, these disturbance predictors showed negative effects on taxonomic diversity irrespective to ontogenetic stage. Moreover, the density of people and livestock near the plot were the main predictors of these negative effects. Species composition differed between plots with low and high level of disturbance, especially in relation to hard wood species, which were rare in the plots highly disturbed. The third and last chapter analyzed how the adult, sapling and seedling communities, surveyed previously, were affected by chronic disturbances from the viewpoint of the phylogenetic diversity and structure. In this chapter the chronic disturbance predictors described above were combined into a chronic disturbance index. The diversity of families expected to the local evolutionary history and the mean phylogenetic distance between the individuals were reduced in plots with higher level of disturbance for all ontogenetic stages. Sapling and seeedling communities had higher degree of relatedness in most disturbed sites, being Euphorbiaceas and Cinidoscolus taxa responsible for this increasing in the relatedness degree. Overall, this thesis demonstrates that chronic anthropogenic disturbance at Caatinga could not continue to be neglected, as it imposes deleterious effects to the taxonomic and phylogenetic diversity of wood plant assemblages. Management strategies conciliating forest use and the maintenance of Caatinga biodiversity are urgent.
37

Prioridades para a conservação de anfíbios da Mata Atlântica / Conservation priorities for amphibians of the Atlantic forest

Silva, Priscila Lemes de Azevedo 18 March 2014 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-09-16T13:35:24Z No. of bitstreams: 2 Tese - Priscila Lemes de Azevedo Silva - 2014.pdf: 8738399 bytes, checksum: ebb4f9ec58380c199dc16142d8009cac (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-16T15:35:18Z (GMT) No. of bitstreams: 2 Tese - Priscila Lemes de Azevedo Silva - 2014.pdf: 8738399 bytes, checksum: ebb4f9ec58380c199dc16142d8009cac (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-16T15:35:18Z (GMT). No. of bitstreams: 2 Tese - Priscila Lemes de Azevedo Silva - 2014.pdf: 8738399 bytes, checksum: ebb4f9ec58380c199dc16142d8009cac (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-03-18 / Global processes such as: habitat loss, overexploitation, invasive species and climate change are driving many species to extinction. In the face of these threats, the development of systematic planning which indicates the most important biodiversity conservation areas has become widely accepted. The establishment of protected areas is the main strategy for the protection of biodiversity and maintenance of ecosystem processes due to its feasibility and economic cost. However, species distribution can be altered by global climate change and, possibly, the current network of protected areas may not be sufficient for species representation in future scenarios. The impact of climate change on biodiversity can be anticipated by spatial prioritization for conservation through the development of dynamic conservation plans. However, it is clear that some species have a more important ecological role than others (due to their biological and life history characteristics) which includes the unique challenge of taking an integrated view of biodiversity in conservation planning into account. The Atlantic Forest is a lush biome which holds 7.7% of the world's known species of amphibians and high concentration of endemic species. However, the Atlantic Forest is also one of the most threatened tropical biomes of the world, mainly due to the loss and fragmentation of natural habitats. This thesis provides proposals for conservation efforts, considering the possible effects of climate change and also the wider aspects of biodiversity. For this, I used the available amphibian data from the Red List of Threatened Species of the International Union for Conservation of Nature, available climate models, information on protected areas by the World Database on Protected Areas, and attributes of species and the phylogenetic tree consistent with specific literature. Chapter 1 highlights a discussion on the impact of climate change and priorities for biodiversity conservation and the importance of including the functional and phylogenetic diversity in conservation efforts. Chapter 2 brings a discussion about available data for conservation studies, as well as the advantages and disadvantages of using maps of extent of occurrence in systematic planning for conservation. Chapter 3 shows the effectiveness of protected areas in maintaining species richness under climate change from consensual projections of species distribution models for amphibians inhabiting of the Atlantic Forest. In this chapter, we identified that protected areas may gain or lose species due to climate change according to the location of the current network of protected areas. Chapter 4 presents an alternative approach to complement the existence of protected areas and incorporates possible changes in species distribution. The prioritization is based mainly on the distribution of species in both present and future scenarios. This chapter outlines a conservation plan that minimizes the effects of climate change on species dispersion. Besides these effects on species dispersion, this solution also minimizes the uncertainty associated with distribution models and prioritizing areas of low uncertainty. Chapter 5 explains the spatial prioritization of conservation, including different aspects of biodiversity, such as: phylogenetic & functional diversity measures and their influence on evolutionary history and underlying ecological processes. The main objective is to identify and compare the places that contain the most information on the taxonomic, phylogenetic and functional diversity, while also indicating the conservation priorities for each biogeographical region of the Atlantic Forest. In conclusion, we present our new and original ideas for conservation and discuss the future prospects and predictions in this area. / Processos globais como a perda de habitat, a superexploração, a invasão de espécies exóticas e as mudanças climáticas estão conduzindo muitas espécies à extinção. Nesse contexto, o desenvolvimento de um planejamento sistemático que indique as áreas mais importantes para a conservação da biodiversidade tem sido amplamente aceito. O estabelecimento de áreas protegidas é a principal estratégia para proteção da biodiversidade e a manutenção dos processos ecossistêmicos devido à viabilidade e ao custo econômico. Todavia, a distribuição das espécies pode ser alterada pelas mudanças climáticas global e, possivelmente, a atual rede de áreas protegidas pode não ser suficiente para representar as espécies no futuro. A priorização espacial para a conservação pode antecipar os impactos das mudanças climáticas sobre a biodiversidade, além de mitigar tais impactos por meio do desenvolvimento de planos dinâmicos de conservação. No entanto, é evidente que algumas espécies têm um papel ecológico mais importante que outras devido às suas características biológicas e à história de vida, portanto, um novo desafio é adotar uma visão integrada da biodiversidade no planejamento da conservação. A Mata Atlântica é um exuberante bioma que detém 7,7% das espécies de anfíbios conhecidas do mundo e grande concentração de espécies endêmicas. Contudo, a Mata Atlântica é também um dos biomas tropicais mais ameaçados do mundo, sobretudo devido à perda e fragmentação dos hábitats naturais. Esta tese fornece propostas para os esforços de conservação, considerando os possíveis efeitos das mudanças climáticas e também os amplos aspectos da biodiversidade. Para tanto, utilizei os dados de anfíbios disponíveis na Lista Vermelha de Espécies Ameaçadas da União Internacional para a Conservação da Natureza para toda a Mata Atlântica,modelos climáticos disponíveis e informações sobre áreas protegidas oferecidas pelo World Database on Protected Areas. Os atributos das espécies e a árvore filogenética estão de acordo coma literatura específica. O capítulo 1 apresenta uma discussão sobre os impactos das mudanças climáticas e as prioridades para a conservação da biodiversidade. Ainda, é discutida a importância de incluir a diversidade funcional e filogenética nos esforços de conservação. O capítulo 2 apresenta os tipos de dados disponíveis para estudos de conservação, além das vantagens e das desvantagens do uso de mapas de extensão de ocorrência no planejamento sistemático para a conservação. O capítulo 3 apresenta a avaliação da eficiência das áreas protegidas em manter a riqueza de espécies no contexto de mudanças climáticas a partir de projeções consensuais dos modelos de distribuição das espécies para anfíbios da Mata Atlântica. Essa avaliação identifica se uma área protegida poderá ganhar ou perder espécies devido às mudanças climáticas considerando a localização da rede atual das áreas protegidas. O capítulo 4 apresenta uma abordagem alternativa para complementar a atual rede de áreas protegidas e incorpora as possíveis mudanças na distribuição das espécies. A priorização baseia-se, principalmente, na distribuição das espécies tanto no presente quanto no futuro e busca minimizar os efeitos dessa mudança na distribuição das espécies a partir de uma medida de dispersão no contexto de mudanças climáticas. Além da medida de dispersão, a solução também minimiza a incerteza associada aos modelos de distribuição, priorizando locais de baixa incerteza. O capítulo 5 apresenta a priorização espacial da conservação, incluindo diferentes aspectos da biodiversidade tal como a diversidade filogenética e funcional cujas medidas inferem tanto a história evolutiva quanto os processos ecológicos subjacentes. O principal objetivo é identificar e comparar os locais que conservam a maior informação sobre a diversidade taxonômica, filogenética e funcional quanto possível. Além disso, são indicadas as prioridades para a conservação para cada região biogeográfica da Mata Atlântica. Finalmente, em sua conclusão, são apresentadas as principais novidades da tese e discutidos os rumos para futuros trabalhos.
38

Diversité et structure du zooplancton : importance pour la conservation de la biodiversité aquatique en zone urbaine

Mimouni, El-Amine 06 1900 (has links)
L'écologie urbaine est un nouveau champ de recherche qui cherche à comprendre les structures et les patrons des communautés et des écosystèmes situés dans des paysages urbains. Les petits plans d’eau sont connus comme des écosystèmes aquatiques qui peuvent contenir une biodiversité considérable pour plusieurs groupes taxonomiques (oiseaux, amphibiens, macroinvertébrés), ce qui en fait des écosystèmes intéressants pour les études de conservation. Cependant, la biodiversité du zooplancton, un élément central des réseaux trophiques aquatiques, n’est pas entièrement connue pour les plans d’eaux urbains et devrait être mieux décrite et comprise. Cette étude a évalué les patrons de biodiversité des communautés zooplanctoniques dans des plans d’eau urbains sur l’Ile de Montréal et leurs sources de variation. Des suggestions pour l’évaluation et la conservation de la biodiversité sont aussi discutées. La biodiversité zooplanctonique des plans d’eaux urbains s’est avérée être assez élevée, avec les cladocères et les rotifères montrant les contributions à la diversité gamma et bêta les plus élevées. Sur l’ensemble des plans d’eau, il y avait une corrélation négative entre les contributions à la bêta diversité des cladocères et des rotifères. Au niveau de chaque plan d'eau, la zone littorale colonisée par des macrophytes s'est avérée être un habitat important pour la biodiversité zooplactonique, contribuant considérablement à la richesse en taxons, souvent avec une différente composition en espèces. Les communautés zooplanctoniques répondaient aux facteurs ascendants et descendants, mais aussi aux pratiques d’entretien, car le fait de vider les plans d’eau en hiver affecte la composition des communautés zooplanctoniques. Les communautés de cladocères dans ces plans d’eau possédaient des quantités variables de diversité phylogénétique, ce qui permet de les classer afin de prioriser les sites à préserver par rapport à la diversité phylogénétique. Le choix des sites à préserver afin de maximiser la diversité phylogénétique devrait être correctement établi, afin d’eviter de faire des choix sous-optimaux. Cependant, pour des taxons tels que les cladocères, pour lesquels les relations phylogénétiques demeurent difficiles à établir, placer une confiance absolue dans un seul arbre est une procédure dangereuse. L’incorporation de l’incertitude phylogénétique a démontré que, lorsqu’elle est prise en compte, plusieurs différences potentielles entre la diversité phylogenétique ne sont plus supportées. Les patrons de composition des communautés différaient entre les plans d’eau, les mois et les zones d’échantillonnage. Etant donné les intéractions sont significatives entres ces facters; ceci indique que tous ces facteurs devraient êtres considérés. L’urbanisation ne semblait pas sélectionner pour un type unique de composition des groupes alimentaires, étant donné que les communautés pouvaient changer entres des assemblages de types alimentaires différents. Les variables environnementales, surtout la couverture du plan d’eau en macrophytes, étaient des facteurs importants pour la biodiversité zooplanctonique, affectant la richesse spécifique de divers groupes taxonomiques et alimentaires. Ces variables affectaient aussi la composition des communautés, mais dans une moindre mesure, étant des variables explicatives modestes, ce qui indiquerait le besoin de considérer d’autres processus. / Urban ecology is an emerging research field that seeks to understand the structures and patterns of communities and ecosystems located in urban landscapes. Small waterbodies are known as aquatic ecosystems that can harbour notable biodiversity for various taxonomic groups (birds, amphibians, macroinvertebrates), making them interesting ecosystems for conservation studies. However, the biodiversity of zooplankton, a central element of aquatic trophic networks, is still not entirely known for urban waterbodies and should be better described and understood. This study examined the biodiversity patterns of zooplanktonic communities in urban waterbodies on the Island of Montreal and their sources of variation. Suggestions for biodiversity assessment and for biodiversity preservation are also discussed. Zooplankton biodiversity urban waterbodies proved to be quite high, with cladoceran and rotifer taxa showing the highest contributions to gamma and beta diversity. Across waterbodies, there was a negative correlation between the contributions to cladoceran and rotifer beta diversity. Within waterbodies, the littoral zone showing macrophytes proved to be an important habitat for zooplankton biodiversity, considerably contributing species richness, often with a different species composition. Zooplankton communities responded to bottom-up and top-down forces, but also management practices, as waterbody emptying in winter affected zooplankton community composition. Cladoceran communities in these waterbodies showed varying amounts of phylogenetic diversity, which allowed them to be ranked in order to prioritize sites to preserve with regards to phylogenetic diversity. Selection of sites to preserve in order to maximize phylogenetic diversity should be properly guided, in order to avoid making suboptimal choices. However, for taxa such as Cladocera, for which phylogenetic relationships remain difficult to establish, placing absolute confidence in a single tree is a dangerous procedure. Incorporation of phylogenetic uncertainty showed that, when it is taken into account, then several potential differences in phylogenetic diversity were not supported anymore. Community composition patterns differed between waterbodies, months and sampling zones. Due to the presence of significant interactions between these factors, this indicates that all these factors should be considered. Urbanization did not seem to select for a single type of feeding group composition, as communities in waterbodies could shift between assemblages with different feeding types. Environmental variables, especially waterbody macrophyte coverage, were important factors for zooplankton biodiversity, positively affected species richness of various taxonomic groups and feeding groups. These variables also affected community composition, but to a lesser extent, being modest predictor variables, indicating the need to consider other processes.
39

Metagenomic Analyses of Glacier Ice / Metagenomanalysen von Gletschereis

Simon, Carola 21 January 2009 (has links)
No description available.
40

The Macroecology of Island Floras

Weigelt, Patrick 17 December 2013 (has links)
Marine Inseln beherbergen einen großen Teil der biologischen Vielfalt unseres Planeten und weisen gleichzeitig einen hohen Anteil endemischer Arten auf. Inselbiota sind allerdings zudem besonders anfällig für anthropogene Einflüsse wie den globalen Klimawandel, Habitatverlust und invasive Arten. Für ihren Erhalt ist es daher wichtig, die ökologischen Prozesse auf Inseln detailliert zu verstehen. Aufgrund ihrer definierten Größe und isolierten Lage eignen sich Inseln als Modellsysteme in der ökologischen und evolutionären Forschung. Der Großteil der bisherigen Inselstudien hat sich allerdings mit kleinräumigen Mustern befasst, so dass standardisierte globale Daten zu den biogeographischen Eigenschaften und eine makroökologische Synthese ihrer Biota bislang fehlen. In dieser Arbeit stelle ich eine physische und bioklimatische Charakterisierung der Inseln der Welt vor und behandle die Frage, wie abiotische Inseleigenschaften die Diversität von Inselfloren beeinflussen. Ich bearbeite zwei Hauptaspekte dieser Fragestellung: Zuerst konzentriere ich mich auf historische und heutige Klimabedingungen und physische Inseleigenschaften als Triebfedern von Pflanzendiversitätsmustern auf Inseln. Hierbei setze ich einen Schwerpunkt auf die räumliche Anordnung von Inseln und Struktur von Archipelen. Als Zweites behandle ich taxon-spezifische Unterschiede in der Antwort von Diversitätsmustern auf abiotische Faktoren. Hierzu stelle ich eine globale Datenbank mit historischen und heutigen Klimabedingungen und physischen Eigenschaften, wie Fläche, Isolation und Geologie, von 17883 Inseln größer als 1 km² vor. Mit Hilfe von Ordinations- und Klassifikationsverfahren charakterisiere und klassifiziere ich die Inseln in einem multidimensionalen Umweltraum. Außerdem entwickele ich einen Satz von ökologisch relevanten Maßen zur Beschreibung von Isolation von Inseln und ihrer räumlichen Anordnung in Archipelen, darunter Maße zu Trittstein-Inseln, Wind- und Meeresströmungen, klimatischer Ähnlichkeit, Distanzen zwischen Inseln und umgebender Landfläche. Diese Maße berücksichtigen verschiedene Aspekte von Isolation, welche Immigration, Artbildung und Aussterben auf Inseln sowie Austausch zwischen Inseln beeinflussen. Um abiotische Bedingungen mit biotischen Eigenschaften von Inselfloren in Verbindung zu bringen, nutze ich eine für diese Arbeit erstellte Datenbank aus 1295 Insel-Artenlisten, die insgesamt ca. 45000 heimische Gefäßpflanzenarten umfassen. Dies ist der umfassendste und erste globale Datensatz für Pflanzen auf Inseln, der Artidentitäten anstatt lediglich Artenzahlen beinhaltet. Die globale Insel-Charakterisierung bestätigt quantitativ, dass sich Inseln in bioklimatischen und physischen Eigenschaften vom Festland unterscheiden. Inseln sind im Durchschnitt signifikant kühler, feuchter und weniger saisonal geprägt als das Festland. Die weiteren Ergebnisse zeigen, dass eine sorgfältige Beschreibung der räumlich-physischen Eigenschaften von Inseln und Archipelen nötig ist, um die Diversitätsmuster ihrer Biota zu verstehen. Isolation ist nach Inselfläche der zweitwichtigste Einflussfaktor für den Gefäßpflanzenartenreichtum auf Inseln. Von den verglichenen Isolationsmaßen eignet sich der Anteil an umgebender Landfläche am besten zur Erklärung der Artenzahlen. Außerdem erhöht sich durch die Berücksichtigung von Trittsteininseln, großen Inseln als Quell-Landflächen und klimatischer Ähnlichkeit der Quell-Landflächen die Vorhersagekraft der Modelle. Isolation spielt eine geringere Rolle auf großen Inseln, wo in situ Diversifizierung den negativen Effekt von Isolation auf Immigration ausgleicht. Die räumliche Struktur innerhalb von Archipelen ist von besonderer Bedeutung für β-Diversität, d.h. für den Unterschied in der Artenzusammensetzung der Inseln. Außerdem beeinflusst sie indirekt, durch den Effekt auf die β-Diversität, auch die γ-Diversität, d.h. die Diversität des gesamten Archipels. Die Ergebnisse heben die enorme Bedeutung der relativen räumlichen Position von Inseln zueinander für Diversitätsmuster auf Inseln hervor und zeigen die Notwendigkeit für Inselforschung und Naturschutz, Inseln im Kontext ihres Archipels zu betrachten. Die Ergebnisse für Farne auf südostasiatischen Inseln zeigen, dass die Bedeutung von physischen Inseleigenschaften für Diversität kontinuierlich mit der Größe der betrachteten Untersuchungsfläche von der Insel- bis zur Plotebene abnimmt, wohingegen der Einfluss von lokalen Umweltbedingungen zunimmt. Lokale Artgemeinschaften sind häufig gesättigt, wodurch die Anzahl an Arten, die aus dem regionalen Artenbestand einwandern können, limitiert wird. Um Vorhersagen über lokalen Artenreichtum zu machen, ist es daher wichtig, die Skalenabhängigkeit der Effekte des regionalen Artenbestandes zu berücksichtigen. Großgruppen von Pflanzen unterscheiden sich in ihrer Ausbreitungsfähigkeit, ihrem Genfluss, Artbildungsraten und Anpassungen an das Klima. Dementsprechend zeigen die vergleichenden Analysen zwischen taxonomischen Pflanzengruppen deutliche Unterschiede in der Reaktion von Artenreichtum und phylogenetischen Diversitätsmustern auf abiotische Faktoren. Die Arten-Fläche-Beziehung, d.h. die Zunahme von Artendiversität mit zunehmender Fläche, variiert zwischen den Pflanzengruppen. Die Steigung der Arten-Fläche-Beziehung ist für Spermatophyten größer als für Pteridophyten und Bryophyten, wohingegen der y-Achsenabschnitt kleiner ist. Unter der Annahme, dass Merkmale und klimatische Anpassungen innerhalb von taxonomischen Gruppen phylogenetisch konserviert sind, führen die Filterwirkung von Ausbreitungsbarrieren und Umwelteigenschaften sowie in situ Artbildung zu Gemeinschaften eng verwandter Arten (phylogenetic clustering). Die Ergebnisse zeigen, dass physische und bioklimatische Inseleigenschaften, die mit der Filterwirkung und Artbildung in Verbindung stehen, die phylogenetische Struktur von Inselgemeinschaften beeinflussen. Die Stärke und Richtung der Zusammenhänge variieren zwischen taxonomischen Gruppen. Abiotische Faktoren erklären mehr Variation in phylogenetischer Diversität für alle Angiospermen und Palmen als für Farne, was auf Grund höherer Ausbreitungsfähigkeit und größerer Verbreitungsgebiete von Farnen den Erwartungen entspricht. Die abiotische Charakterisierung und Klassifizierung der weltweiten Inseln und die zugehörigen Daten ermöglichen eine integrativere Berücksichtigung von Inseln in der makroökologischen Forschung. In dieser Arbeit präsentiere ich die ersten Vorhersagen globaler Pflanzenartenvielfalt auf Inseln und die ersten Analysen zu unterschiedlichen Diversitätskomponenten (α, β, γ und phylogenetische Diversität) von Inselsystemen und ihren abiotischen Einflussfaktoren auf globalem Maßstab. Ich zeige, dass Zusammenhänge zwischen Umweltfaktoren und Artenzahl sowie phylogenetischen Eigenschaften von Inselgemeinschaften zwischen unterschiedlichen taxonomischen Gruppen in Abhängigkeit ihrer vorwiegenden Ausbreitungs- und Artbildungseigenschaften variieren können. Dies ist eine neue Sichtweise in der makroökologischen Inselforschung, die Rückschlüsse auf die Mechanismen hinter Diversitätsmustern von Pflanzen auf Inseln erlaubt. Ein detailliertes Verständnis davon, wie Diversität unterschiedlicher Pflanzengruppen durch Immigration und Diversifizierung auf Inseln entsteht, dürfte auch das Verständnis globaler Diversitätsmuster im Allgemeinen verbessern.

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