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Auteur Mouillot, D.; De Bortoli, J.; Leprieur, F.; Parravicini, V.; Kulbicki, M.; Bellwood, D.R. url  doi
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  Titre The challenge of delineating biogeographical regions: nestedness matters for Indo-Pacific coral reef fishes Type Article scientifique
  Année 2013 Publication Revue Abrégée Journal of Biogeography  
  Volume 40 Numéro 12 Pages 2228-2237  
  Mots-Clés (up) -diversity; Archipelago; Coral Triangle; Indo-Australian; Pae; beta-diversity; biodiversity hotspots; conservation; delineation; dissimilarity; dung beetles; endemicity; evolutionary history; global; historical biogeography; nestedness; parsimony analysis; partitioning; patterns; reef fish assemblages; spatial-patterns; turnover  
  Résumé AimThe delineation of regions is a critical procedure in biogeography, but there is still no consensus about the best approach. Traditionally, a compositional dissimilarity index and a clustering algorithm are used to partition locations into regions. However, the choice of index and algorithm may have a profound impact on the final result, particularly when locations display different levels of species richness and when they are nested within each other. Our objective was to estimate the influence of species nestedness among locations on the delineation of biogeographical regions. LocationAs a case study, we used coral reef fishes (families Chaetodontidae, Pomacentridae and Labridae) from the Indo-Pacific, where a large richness gradient extends, often as a series of nested assemblages, from the species-rich Indo-Australian Archipelago (Coral Triangle) to species-poor peripheral locations. MethodsWe used the turnover and nestedness components of the SOrensen and Jaccard dissimilarity indices to estimate the effect of nestedness on the delineation of biogeographical regions. In addition, we compared the results with those obtained using a parsimony analysis of endemicity (PAE). ResultsLow Mantel correlation values revealed that the PAE method assembled locations in a very different way than methods based on dissimilarity indices for Indo-Pacific coral reef fishes. We also found that nestedness mattered when delineating biogeographical units because, for both the SOrensen and the Jaccard indices, reef fish assemblages were grouped differently depending on whether we used the turnover component of each index or the complete index, including the nestedness component. The turnover component ignored variation in species richness attributable to differences in habitat area between locations, and permitted a delineation based solely on species replacement. Main conclusionsWe demonstrate that the choice of the component used to measure dissimilarity between species assemblages is critical, because it may strongly influence regional delineations, at least for Indo-Pacific coral reef fishes. We conclude that the two components of the dissimilarity indices can reveal complementary insights into the role that history may have played in shaping extant patterns of biodiversity.  
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  ISSN 0305-0270 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 879  
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Auteur Bouvier, T.; Venail, P.; Pommier, T.; Bouvier, C.; Barbera, C.; Mouquet, N. url  doi
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  Titre Contrasted Effects of Diversity and Immigration on Ecological Insurance in Marine Bacterioplankton Communities Type Article scientifique
  Année 2012 Publication Revue Abrégée PLoS One  
  Volume 7 Numéro 6 Pages  
  Mots-Clés (up) 16s ribosomal-rna; bacterial communities; biodiversity; dispersal; fresh-water; gradient gel-electrophoresis; metacommunities; predictability; productivity; stability  
  Résumé The ecological insurance hypothesis predicts a positive effect of species richness on ecosystem functioning in a variable environment. This effect stems from temporal and spatial complementarity among species within metacommunities coupled with optimal levels of dispersal. Despite its importance in the context of global change by human activities, empirical evidence for ecological insurance remains scarce and controversial. Here we use natural aquatic bacterial communities to explore some of the predictions of the spatial and temporal aspects of the ecological insurance hypothesis. Addressing ecological insurance with bacterioplankton is of strong relevance given their central role in fundamental ecosystem processes. Our experimental set up consisted of water and bacterioplankton communities from two contrasting coastal lagoons. In order to mimic environmental fluctuations, the bacterioplankton community from one lagoon was successively transferred between tanks containing water from each of the two lagoons. We manipulated initial bacterial diversity for experimental communities and immigration during the experiment. We found that the abundance and production of bacterioplankton communities was higher and more stable (lower temporal variance) for treatments with high initial bacterial diversity. Immigration was only marginally beneficial to bacterial communities, probably because microbial communities operate at different time scales compared to the frequency of perturbation selected in this study, and of their intrinsic high physiologic plasticity. Such local “physiological insurance” may have a strong significance for the maintenance of bacterial abundance and production in the face of environmental perturbations.  
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  ISSN 1932-6203 ISBN Médium  
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Auteur Caro, A.; Escalas, A.; Bouvier, C.; Grousset, E.; Lautredou-Audouy, N.; Roques, C.; Charmantier, M.; Gros, O. url  doi
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  Titre Epibiotic bacterial community of Sphaeroma serratum (Crustacea, Isopoda): relationship with molt status Type Article scientifique
  Année 2012 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.  
  Volume 457 Numéro Pages 11-27  
  Mots-Clés (up) 16s ribosomal-rna; Crustacean; DGGE band pattern; Epibiotic biofilm; Molt cycle; Sphaeroma; fish; gastropod; gradient gel-electrophoresis; hydrothermal-vent; in-situ hybridization; mid-atlantic ridge; oxidizing bacteria; phylogenetic diversity; riftia-pachyptila; shrimp rimicaris-exoculata; urothoe-poseidonis  
  Résumé Sphaeroma serratum is a marine isopod species that inhabits seashores from Europe to West Africa. The individuals live under stones in direct contact with reduced sediments and harbour a diverse bacterial community on the cuticle of their pleopods. We investigated the diversity of these epibiotic bacteria on male (pubescent and senescent) and female specimens with electron microscopic observations and molecular tools. The microbial community of S. serratum was shown to be composed of at least 5 bacterial morphotypes observed on the pleopodal cuticle in all male specimens. Using fluorescence in situ hybridization, we identified 5 major phylogenetic groups (alpha-, beta-, gamma- and delta-Proteobacteria and Archaea) whereas denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments of epibiotic bacteria revealed 50 bands. The bacterial community associated with S. serratum seems more diverse than in other marine crustaceans, such as Rimicaris. The relative diversity of this bacterial community was also studied in relation to the molt cycle. The comparison of DGGE band patterns of several individuals from female, pubescent male and senescent male groups revealed that the bacterial community diversity was dependent on the sex and the age of the individuals and more generally on the molt status.  
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  ISSN 0171-8630 ISBN Médium  
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Auteur Auguet, J.C.; Montanie, H.; Hartmann, H.J.; Lebaron, P.; Casamayor, E.O.; Catala, P.; Delmas, D. doi  openurl
  Titre Potential effect of freshwater virus on the structure and activity of bacterial communities in the Marennes-Oleron Bay (France) Type Article scientifique
  Année 2009 Publication Revue Abrégée Microb Ecol  
  Volume 57 Numéro 2 Pages 295-306  
  Mots-Clés (up) 16S/genetics Seasons Seawater/microbiology/virology Viruses/*growth & development *Water Microbiology; Bacteria/genetics/*growth & development/*virology Biodiversity Colony Count; Bacterial/genetics France Fresh Water/virology Polymorphism; Microbial DNA Fingerprinting DNA; Ribosomal; Single-Stranded Conformational Population Dynamics RNA  
  Résumé Batch culture experiments using viral enrichment were conducted to test the response of a coastal bacterial community to autochthonous (i.e., co-existing) or allochthonous riverine viruses. The effects of viral infections on bacterial dynamics and activity were assessed by epifluorescence microscopy and thymidine incorporation, respectively, whereas the effect of viral infection on bacterial community composition was examined by polymerase chain reaction-single strand conformation polymorphism 16S ribosomal RNA fingerprinting. The percentages of high nucleic acid-containing cells, evaluated by flow cytometry, were significantly correlated (r2=0.91, n=12, p<0.0001) to bacterial production, making this value a good predictor of active cell dynamics along the study. While confinement and temperature were the two principal experimental factors affecting bacterial community composition and dynamics, respectively, additions of freshwater viruses had significant effects on coastal bacterial communities. Thus, foreign viruses significantly reduced net bacterial population increase as compared to the enrichment treated with inactivated virus. Moreover, freshwater viruses recurrently and specifically affected bacterial community composition, as compared to addition of autochthonous viruses. In most cases, the combined treatment viruses and freshwater dissolved organic matter helped to maintain or even enhance species richness in coastal bacterial communities in agreement to the 'killing the winner' hypothesis. Thus, riverine virus input could potentially influence bacterial community composition of the coastal bay albeit with modest modification of bulk bacterial growth.  
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Auteur Auguet, J.C.; Nomokonova, N.; Camarero, L.; Casamayor, E.O. doi  openurl
  Titre Seasonal changes of freshwater ammonia-oxidizing archaeal assemblages and nitrogen species in oligotrophic alpine lakes Type Article scientifique
  Année 2011 Publication Revue Abrégée Appl Environ Microbiol  
  Volume 77 Numéro 6 Pages 1937-1945  
  Mots-Clés (up) 16S/genetics Seasons Spain; Ammonia/*metabolism Archaea/classification/genetics/*metabolism Biodiversity Fresh Water Molecular Sequence Data Nitrogen/*metabolism Oxidoreductases/genetics Phylogeny Polymerase Chain Reaction RNA; Ribosomal  
  Résumé The annual changes in the composition and abundance of ammonia-oxidizing archaea (AOA) were analyzed monthly in surface waters of three high mountain lakes within the Limnological Observatory of the Pyrenees (LOOP; northeast Spain) using both 16S rRNA and functional (ammonia monooxygenase gene, amoA) gene sequencing as well as quantitative PCR amplification. The set of biological data was related to changes in nitrogen species and to other relevant environmental variables. The whole archaeal assemblage was dominated by phylotypes closely related to the crenarchaeal 1.1a group (58% +/- 18% of total 16S rRNA gene sequences), and consistent structural changes were detected during the study. Water temperature was the environmental variable that better explained spring, summer, and winter (ice-covered lakes) archaeal assemblage structure. The amoA gene was detected year round, and seasonal changes in amoA gene composition were well correlated with changes in the archaeal 16S rRNA gene pool. In addition, copy numbers of both the specific 1.1a group 16 rRNA and archaeal amoA genes were well correlated, suggesting that most freshwater 1.1a Crenarchaeota had the potential to carry out ammonia oxidation. Seasonal changes in the diversity and abundance of AOA (i.e., amoA) were better explained by temporal changes in ammonium, the substrate for nitrification, and mostly nitrite, the product of ammonia oxidation. Lacustrine amoA gene sequences grouped in coherent freshwater phylogenetic clusters, suggesting that freshwater habitats harbor typical amoA-containing ecotypes, which is different from soils and seas. We observed within the freshwater amoA gene sequence pool a high genetic divergence (translating to up to 32% amino acid divergence) between the spring and the remaining AOA assemblages. This suggests that different AOA ecotypes are adapted to different temporal ecological niches in these lakes.  
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