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Auteur Auguet, J.C.; Barberan, A.; Casamayor, E.O.
Titre Global ecological patterns in uncultured Archaea Type Article scientifique
Année 2010 Publication (up) Revue Abrégée Isme J
Volume 4 Numéro 2 Pages 182-190
Mots-Clés 16S/genetics; Archaea/classification/genetics/*physiology DNA; Ribosomal; Ribosomal/genetics *Ecosystem Multivariate Analysis Phylogeny Plankton/classification/genetics RNA; Ribosomal/genetics RNA
Résumé We have applied a global analytical approach to uncultured Archaea that for the first time reveals well-defined community patterns along broad environmental gradients and habitat types. Phylogenetic patterns and the environmental factors governing the creation and maintenance of these patterns were analyzed for c. 2000 archaeal 16S rRNA gene sequences from 67 globally distributed studies. The sequences were dereplicated at 97% identity, grouped into seven habitat types, and analyzed with both Unifrac (to explore shared phylogenetic history) and multivariate regression tree (that considers the relative abundance of the lineages or taxa) approaches. Both phylogenetic and taxon-based approaches showed salinity and not temperature as one of the principal driving forces at the global scale. Hydrothermal vents and planktonic freshwater habitats emerged as the largest reservoirs of archaeal diversity and consequently are promising environments for the discovery of new archaeal lineages. Conversely, soils were more phylogenetically clustered and archaeal diversity was the result of a high number of closely related phylotypes rather than different lineages. Applying the ecological concept of 'indicator species', we detected up to 13 indicator archaeal lineages for the seven habitats prospected. Some of these lineages (that is, hypersaline MSBL1, marine sediment FCG1 and freshwater plSA1), for which ecological importance has remained unseen to date, deserve further attention as they represent potential key archaeal groups in terms of distribution and ecological processes. Hydrothermal vents held the highest number of indicator lineages, suggesting it would be the earliest habitat colonized by Archaea. Overall, our approach provided ecological support for the often arbitrary nomenclature within uncultured Archaea, as well as phylogeographical clues on key ecological and evolutionary aspects of archaeal biology.
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Auteur Benedetti, F.; Ayata, S.-D.; Irisson, J.-O.; Adloff, F.; Guilhaumon, F.
Titre Climate change may have minor impact on zooplankton functional diversity in the Mediterranean Sea Type Article scientifique
Année 2019 Publication (up) Revue Abrégée Divers. Distrib.
Volume 25 Numéro 4 Pages 568-581
Mots-Clés biogeography; calanus-helgolandicus; climate change; communities; conservation; fish assemblages; framework; functional diversity; future; marine biodiversity; Mediterranean Sea; niche modelling; null model; ocean; trait; zooplankton
Résumé Aim To assess the impact of climate change on the functional diversity of marine zooplankton communities. Location The Mediterranean Sea. Methods We used the functional traits and geographic distributions of 106 copepod species to estimate the zooplankton functional diversity of Mediterranean surface assemblages for the 1965-1994 and 2069-2098 periods. Multiple environmental niche models were trained at the global scale to project the species habitat suitability in the Mediterranean Sea and assess their sensitivity to climate change predicted by several scenarios. Simultaneously, the species traits were used to compute a functional dendrogram from which we identified seven functional groups and estimated functional diversity through Faith's index. We compared the measured functional diversity to the one originated from null models to test if changes in functional diversity were solely driven by changes in species richness. Results All but three of the 106 species presented range contractions of varying intensity. A relatively low decrease of species richness (-7.42 on average) is predicted for 97% of the basin, with higher losses in the eastern regions. Relative sensitivity to climate change is not clustered in functional space and does not significantly vary across the seven copepod functional groups defined. Changes in functional diversity follow the same pattern and are not different from those that can be expected from changes in richness alone. Main conclusions Climate change is not expected to alter copepod functional traits distribution in the Mediterranean Sea, as the most and the least sensitive species are functionally redundant. Such redundancy should buffer the loss of ecosystem functions in Mediterranean zooplankton assemblages induced by climate change. Because the most negatively impacted species are affiliated to temperate regimes and share Atlantic biogeographic origins, our results are in line with the hypothesis of increasingly more tropical Mediterranean communities.
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Langue English Langue du Résumé Titre Original
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ISSN 1366-9516 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2582
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Auteur Auguet, J.C.; Casamayor, E.O.
Titre Partitioning of Thaumarchaeota populations along environmental gradients in high mountain lakes Type Article scientifique
Année 2013 Publication (up) Revue Abrégée FEMS Microbiology Ecology
Volume 84 Numéro 1 Pages 154-164
Mots-Clés amoA gene Euryarchaeota Freshwater Nitrogen Plankton SAGMGC
Résumé We investigated the spatial distribution and diversity of ammonia-oxidizing Archaea (AOA) across gradients of pH, trophic status and altitude in a set of high mountain lakes (Limnological Observatory of the Pyrenees, north-east Spain). Both phylogeny- and taxonomy-based approaches revealed well-defined AOA community patterns with pH as the main potential driving environmental factor. The I.1a and SAGMGC-1 Thaumarchaeota clusters, and their potentially associated amoA gene variants (clusters Fresh 5 and Soil/Fresh 1, respectively) showed highest relative abundances in the most oligotrophic lakes. Euryarchaeota (i.e. HV-Fresh cluster, Methanomicrobiales and Thermoplasmatales) dominated in lakes with higher trophic status. Phylogenetic diversity (PD) in Pyrenean lakes was 1.5- to 2.3-fold higher than the PD from an equivalent number of globally distributed marine and soil sites. We observed segregated distributions for SAGMGC-1, preferentially distributed in the lakes with the lowest pH (< 5) and the highest nitrite concentration (> 0.12 μm), and I.1a in lakes with lower nitrite and dissolved organic carbon concentrations below 0.5 mg L-1. Overall, these results showed strong selection by local environmental conditions, unveiled new ecological niches for freshwater SAGMGC-1 in low pH oligotrophic lakes, and suggested specific and successful adaptations of planktonic archaea to the high mountain lakes landscape. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
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Auteur Catherine, A.; Selma, M.; Mouillot, D.; Troussellier, M.; Bernard, C.
Titre Patterns and multi-scale drivers of phytoplankton species richness in temperate peri-urban lakes Type Article scientifique
Année 2016 Publication (up) Revue Abrégée Science of The Total Environment
Volume 559 Numéro Pages 74-83
Mots-Clés Lake- and catchment-scale; Phytoplankton; Productivity–diversity relationship; Random forest; Residuals analysis; species richness
Résumé Local species richness (SR) is a key characteristic affecting ecosystem functioning. Yet, the mechanisms regulating phytoplankton diversity in freshwater ecosystems are not fully understood, especially in peri-urban environments where anthropogenic pressures strongly impact the quality of aquatic ecosystems. To address this issue, we sampled the phytoplankton communities of 50 lakes in the Paris area (France) characterized by a large gradient of physico-chemical and catchment-scale characteristics. We used large phytoplankton datasets to describe phytoplankton diversity patterns and applied a machine-learning algorithm to test the degree to which species richness patterns are potentially controlled by environmental factors. Selected environmental factors were studied at two scales: the lake-scale (e.g. nutrients concentrations, water temperature, lake depth) and the catchment-scale (e.g. catchment, landscape and climate variables). Then, we used a variance partitioning approach to evaluate the interaction between lake-scale and catchment-scale variables in explaining local species richness. Finally, we analysed the residuals of predictive models to identify potential vectors of improvement of phytoplankton species richness predictive models. Lake-scale and catchment-scale drivers provided similar predictive accuracy of local species richness (R2 = 0.458 and 0.424, respectively). Both models suggested that seasonal temperature variations and nutrient supply strongly modulate local species richness. Integrating lake- and catchment-scale predictors in a single predictive model did not provide increased predictive accuracy; therefore suggesting that the catchment-scale model probably explains observed species richness variations through the impact of catchment-scale variables on in-lake water quality characteristics. Models based on catchment characteristics, which include simple and easy to obtain variables, provide a meaningful way of predicting phytoplankton species richness in temperate lakes. This approach may prove useful and cost-effective for the management and conservation of aquatic ecosystems.
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ISSN 0048-9697 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1566
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Auteur Maloufi, S.; Catherine, A.; Mouillot, D.; Louvard, C.; Couté, A.; Bernard, C.; Troussellier, M.
Titre Environmental heterogeneity among lakes promotes hyper β-diversity across phytoplankton communities Type Article scientifique
Année 2016 Publication (up) Revue Abrégée Freshw Biol
Volume 61 Numéro 5 Pages 633-645
Mots-Clés environmental heterogeneity; meta-community ecology; Phytoplankton; species sorting; turnover
Résumé * The extent to which stochastic and deterministic processes influence variations in species communities across space and time remains a central question in theoretical and applied ecology. Despite their high dispersal ability, the composition of phytoplankton communities displays striking spatial variations among lakes even at small spatial scale. * To investigate the mechanisms underlying the distribution of phytoplankton species, we evaluate the contribution of stochastic, spatial and environmental processes in determining β-diversity patterns of phytoplankton at a regional scale. Phytoplankton communities were surveyed in 50 different lakes from north-central France, a region characterised by strong environmental heterogeneity. * The regional species pool was characterised by extremely high β-diversity levels, which were mainly explained by species replacement (i.e. turnover) rather than by differences in species richness (i.e. nestedness). Null models of random species distribution and spatial processes failed to explain observed β-diversity patterns. At the opposite, local environmental conditions strongly influenced the degree of uniqueness of local phytoplankton communities, with the most contrasted environments, including human-dominated areas, promoting highly distinct phytoplankton communities. * Our results suggest that species-sorting mechanisms that arise from variations in local environmental conditions drive high species turnover at the region scale. Thus, in a landscape strongly impacted by cultural eutrophication, further anthropogenic impacts on aquatic ecosystems would likely induce regional homogenisation of phytoplankton communities. Overall, our study supports the fact that the management of lakes and reservoirs in anthropic landscapes should aim at maintaining environmental heterogeneity while preventing further eutrophication in order to favour the maintenance of high phytoplankton β- and γ-diversity.
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ISSN 1365-2427 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1569
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