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Leroy, C.; Jauneau, A.; Martinez, Y.; Cabin-Flaman, A.; Gibouin, D.; Orivel, J.; Séjalon-Delmas, N. |
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Exploring fungus-plant N transfer in a tripartite ant-plant-fungus mutualism |
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Journal Article |
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2017 |
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Annals of Botany |
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Annals of Botany |
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120 |
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3 |
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417-426 |
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Ascomycetes; endophytic fungi; Hirtella physophora; microscopy; mutualism; myrmecophyte; NanoSIMS; stable isotope |
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Background and Aims The plant Hirtella physophora, the ant Allomerus decemarticulatus and a fungus, Trimmatostroma sp., form a tripartite association. The ants manipulate both the plant trichomes and the fungus to build galleries under the stems of their host plant used to capture prey. In addition to its structural role, the fungus also improves nutrient uptake by the host plant. But it still remains unclear whether the fungus plays an indirect or a direct role in transferring nutrients to the plant. This study aimed to trace the transfer of N from the fungus to the plant's stem tissue. • Methods Optical microscopy and transmission electron microscopy (TEM) were used to investigate the presence of fungal hyphae in the stem tissues. Then, a 15N-labelling experiment was combined with a nanoscale secondary-ion mass spectrometry (NanoSIMS 50) isotopic imaging approach to trace the movement of added 15N from the fungus to plant tissues. • Key Results The TEM images clearly showed hyphae inside the stem tissue in the cellular compartment. Also, fungal hyphae were seen perforating the wall of the parenchyma cell. The 15N provisioning of the fungus in the galleries resulted in significant enrichment of the 15N signature of the plant's leaves 1 d after the 15N-labelling solution was deposited on the fungus-bearing trap. Finally, NanoSIMS imaging proved that nitrogen was transferred biotrophically from the fungus to the stem tissue. • Conclusions This study provides evidence that the fungi are connected endophytically to an ant-plant system and actively transfer nitrogen from 15N-labelling solution to the plant's stem tissues. Overall, this study underlines how complex the trophic structure of ant-plant interactions is due to the presence of the fungus and provides insight into the possibly important nutritional aspects and tradeoffs involved in myrmecophyte-ant mutualisms. © The Author 2017. |
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Laboratoire de Recherches en Sciences Végétales, Université de Toulouse, CNRS, UPS, France |
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Export Date: 2 October 2017 |
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EcoFoG @ webmaster @ |
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767 |
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Céréghino, R.; Françoise, L.; Bonhomme, C.; Carrias, J.-F.; Compin, A.; Corbara, B.; Jassey, V.; Leflaive, J.; Rota, T.; Farjalla, V.; Leroy, C. |
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Desiccation resistance traits predict freshwater invertebrate survival and community response to drought scenarios in a Neotropical ecosystem |
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Journal Article |
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2020 |
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Ecological Indicators |
Abbreviated Journal |
Ecol. Indic. |
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119 |
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106839 |
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Climate change; Functional traits; Lt50; Macroinvertebrates; Rainforests; Biodiversity; Climate change; Driers (materials); Drought; Environmental management; Population statistics; Tanks (containers); Water; Aquatic invertebrates; Climate change adaptation; Controlled conditions; Environmental managers; Freshwater biodiversity; Freshwater invertebrates; Future climate scenarios; Laboratory conditions; Aquatic organisms; aquatic community; biodiversity; climate change; cuticle; desiccation; drought stress; invertebrate; Neotropical Region; population size; survival; French Guiana; Invertebrata |
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The intensification of dry seasons is a major threat to freshwater biodiversity in Neotropical regions. Little is known about resistance to drying stress and the underpinning traits in Neotropical freshwater species, so we don't know whether desiccation resistance allows to anticipate shifts in biological diversity under future climate scenarios. Here, we used the aquatic invertebrates that live in the rainwater-filled leaves of tank bromeliads, to examine the extent to which desiccation resistance of species measured in the laboratory predicts community response to drought intensification in nature. We measured desiccation resistance in 17 invertebrate species (>90% of the biomass usually found in bromeliads of French Guiana) by recording the median lethal time (LT50) of experimental populations exposed to controlled conditions of residual moisture. In the field, we placed rainshelters above tank bromeliads to emulate drought scenarios ranging from the ambient norm to IPCC scenarios and extreme events, and we recorded the response of functional community structure. LT50 ranged from 4.18 to 19.06 days, and was related to cuticle content and dry body mass. Among other functional indicators that represent strategies to optimize resource use under stressful conditions (e.g., habitat use, trophic specialization), LT50 was the best predictor of community structure responses along a gradient of emulated drought intensities. Therefore, species’ LT50s measured under laboratory conditions can be used to forecast aquatic community response to drying stress in nature. Anticipating how species will cope with drought has never been more important for environmental managers to support climate change adaptation. We show that desiccation resistance in freshwater invertebrates is a key indicator of potential population size and local–global range shifts, and this could be especially true in the Neotropics where species have narrow physiological tolerances for climatic variation. © 2020 Elsevier Ltd |
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ECOFOG, AgroParisTech, CIRAD, CNRS, INRA, Université de Guyane, Université des Antilles, Campus Agronomique, Kourou, 97379, France |
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Elsevier B.V. |
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1470160x (Issn) |
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EcoFoG @ webmaster @ |
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941 |
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Denis, T.; Herault, B.; Jaouen, G.; Brunaux, O.; Guitet, S.; Richard-Hansen, C. |
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Black Curassow habitat relationships in terra firme forests of the Guiana Shield: A multiscale approach |
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Journal Article |
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2016 |
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The Condor |
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The Condor |
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118 |
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2 |
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253-273 |
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ABSTRACT The Black Curassow (Crax alector) is a large game bird with Vulnerable conservation status found in north-central South America. We examined its distributional pattern across French Guiana using a large number of environmental descriptors at 3 scales of analysis: landscape, forest type, and microhabitat. We used a hierarchical model with temporary emigration and imperfect detection for data collected by standard distance sampling methods at 35 study sites. At the landscape scale, Black Curassow density decreased with hunting pressure and increased with steeper slopes in both hunted and unhunted areas. Topography appeared to be a good proxy for Black Curassow ecological requirements and probably reflected habitat quality. At the forest scale, population density was negatively correlated with the abundance of palms and Mimosoideae and positively correlated with the abundance of Lauraceae. Botanical families did not directly influence Black Curassow distribution, but rather determined spatial patterns by being markers of a particular forest type. At the microhabitat scale, Black Curassows used hilltops more frequently than other parts of the local topographical gradient. Our multiscale analysis shows that this species' distribution can be explained by biotic or abiotic conditions, regardless of the scale. For conservation, we recommend maintaining connectivity between Black Curassow populations separated by hunted areas. Our predicted densities could be used to adapt hunting quotas across French Guiana's forests. We show that combining field and remote sensing data helps to understand the ecological processes responsible for Black Curassow habitat relationships. |
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American Ornithological Society |
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0010-5422 |
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doi: 10.1650/CONDOR-15-28.1 |
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EcoFoG @ webmaster @ |
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714 |
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Agrawal, Anurag A. ; Boroczky, Katalin ; Haribal, Meena ; Hastings, Amy P. ; White, Ronald, A. ; Jiang, Ren-Wang ; Duplais, Christophe |
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Cardenolides, toxicity, and the costs of sequestration in the coevolutionary interaction between monarchs and milkweeds |
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2021 |
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PNAS |
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118 |
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16 |
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e2024463118 |
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For highly specialized insect herbivores, plant chemical defenses are often co-opted as cues for oviposition and sequestration. In such interactions, can plants evolve novel defenses, pushing herbivores to trade off benefits of specialization with costs of coping with toxins? We tested how variation in milkweed toxins (cardenolides) impacted monarch butterfly ( Danaus plexippus ) growth, sequestration, and oviposition when consuming tropical milkweed ( Asclepias curassavica ), one of two critical host plants worldwide. The most abundant leaf toxin, highly apolar and thiazolidine ring–containing voruscharin, accounted for 40% of leaf cardenolides, negatively predicted caterpillar growth, and was not sequestered. Using whole plants and purified voruscharin, we show that monarch caterpillars convert voruscharin to calotropin and calactin in vivo, imposing a burden on growth. As shown by in vitro experiments, this conversion is facilitated by temperature and alkaline pH. We next employed toxin-target site experiments with isolated cardenolides and the monarch’s neural Na + /K + -ATPase, revealing that voruscharin is highly inhibitory compared with several standards and sequestered cardenolides. The monarch’s typical >50-fold enhanced resistance to cardenolides compared with sensitive animals was absent for voruscharin, suggesting highly specific plant defense. Finally, oviposition was greatest on intermediate cardenolide plants, supporting the notion of a trade-off between benefits and costs of sequestration for this highly specialized herbivore. There is apparently ample opportunity for continued coevolution between monarchs and milkweeds, although the diffuse nature of the interaction, due to migration and interaction with multiple milkweeds, may limit the ability of monarchs to counteradapt. |
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National Academy of Sciences |
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EcoFoG @ webmaster @ |
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1014 |
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Verbeeck, H.; Peylin, P.; Bacour, C.; Bonal, D.; Steppe, K.; Ciais, P. |
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Seasonal patterns of CO2 fluxes in Amazon forests: Fusion of eddy covariance data and the ORCHIDEE model |
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2011 |
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Journal Of Geophysical Research-Biogeosciences |
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J. Geophys. Res.-Biogeosci. |
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116 |
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2 |
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G02018 |
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[1] In some regions of the Amazon, global biogeophysical models have difficulties in reproducing measured seasonal patterns of net ecosystem exchange (NEE) of carbon dioxide. The global process-based biosphere model Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) used in this study showed that a standard model parameterization produces seasonal NEE patterns that are opposite in phase to the eddy flux data of the tropical evergreen forest at the Tapajos km 67 site (Brazil), like many other global models. However, we optimized several key parameters of ORCHIDEE using eddy covariance data of the Tapajos km 67 site in order to identify the driving factors of the seasonal variations in CO2 flux in this tropical forest ecosystem. The validity of the retrieved parameter values was evaluated for two other flux tower sites in the Amazon. The different tested optimization scenarios showed that only a few parameters substantially improve the fit to NEE and latent heat data. Our results confirm that these forests have the ability to maintain high transpiration and photosynthesis during the dry season in association with a large soil depth (D-soil = 10 m) and a rooting system density that decreases almost linearly with depth (H-root = 0.1). Previous analyses of seasonal variations in eddy covariance fluxes indicated that higher GPP levels were reached in the dry season compared to the wet season. Our optimization analysis suggests that this pattern could be caused by a leaf flush at the start of the dry season increasing the photosynthetic capacity of the canopy. Nevertheless, the current model structure is not yet able to simulate such a leaf flush, and we therefore suggest improving the ORCHIDEE model by including a specific phenology module that is driven by light availability for the tropical evergreen plant functional types. In addition, our results highlight both the potential and the limitations of flux data to improve global terrestrial models. Several parameters were not identifiable, and the risk of overfitting of the model was illustrated. Nevertheless, we conclude that these models can be improved substantially by assimilating site level flux data over the tropics. |
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[Verbeeck, Hans; Steppe, Kathy] Univ Ghent, Plant Ecol Lab, Dept Appl Ecol & Environm Biol, Fac Biosci Engn, B-9000 Ghent, Belgium, Email: hans.verbeeck@ugent.be |
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Amer Geophysical Union |
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0148-0227 |
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ISI:000290933500002 |
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EcoFoG @ webmaster @ |
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321 |
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Houel, E.; Rodrigues, A.M.S.; Jahn-Oyac, A.; Bessière, J.-M.; Eparvier, V.; Deharo, E.; Stien, D. |
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In vitro antidermatophytic activity of Otacanthus azureus (Linden) Ronse essential oil alone and in combination with azoles |
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Journal Article |
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2014 |
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Journal of Applied Microbiology |
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J. Appl. Microbiol. |
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116 |
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2 |
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288-294 |
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Antifungal activity; Azoles; Dermatophytes; Essential oil; Otacanthus azureus; Synergy |
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Aims: We determined the chemical composition and investigated the antifungal activity of Otacanthus azureus (Linden) Ronse essential oil (EO) against a range of dermatophytes alone or in combination with azole antifungals. Methods and Results: Aerial parts of the plant were steam-distilled and the obtained oil was analysed by gas chromatography/mass spectrometry and 1H-NMR. It was shown to be largely composed of sesquiterpenes, with the main component being β-copaen-4-α-ol. Using broth microdilution techniques, this oil was found to have remarkable in vitro antifungal activities. Minimum inhibitory concentrations as low as 4 μg ml-1 were recorded. The analysis of the combined effect of the O. azureus EO with azoles using chequerboard assays revealed a synergism between the EO and ketoconazole, fluconazole or itraconazole against Trichophyton mentagrophytes. Notably, the O. azureus essential oil showed low cytotoxicity to VERO cells. Conclusions: The O. azureus essential oil alone or in combination with azoles is a promising antifungal agent in the treatment for human dermatomycoses caused by filamentous fungi. Significance and Impact of the Study: There is much interest in the study of essential oils for the discovery of new antimicrobial drugs. This study has highlighted the antidermatophytic activity of the O. azureus EO. © 2013 The Society for Applied Microbiology. |
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Institut de Recherche pour le Développement (IRD), UMR 152 Pharma-DEV, Toulouse, France |
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13645072 (Issn) |
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Export Date: 9 February 2014; Source: Scopus; Coden: Jamif; Language of Original Document: English; Correspondence Address: Houël, E.; CNRS – UMR Ecologie des Forêts de Guyane (EcoFoG), Institut Pasteur de la Guyane, 23 Avenue Pasteur, BP6010, 97306 Cayenne Cedex, French Guiana; email: emeline.houel@ecofog.gf |
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EcoFoG @ webmaster @ |
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526 |
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Bekaert, E.; Robert, F.; Lippens, P.E.; Menetrier, M. |
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Li-7 NMR Knight Shifts in Li-Sn Compounds: MAS NMR Measurements and Correlation with DFT Calculations |
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Journal Article |
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2010 |
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Journal of Physical Chemistry C |
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J. Phys. Chem. C |
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114 |
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14 |
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6749-6754 |
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Several Li-Sn crystalline phases, LiSn. Li7Sn3, Li5Sn7, Li13Sn5, Li7Sn2, and Li22Sn5. were prepared by ball-milling and studied by Li-7 MAS NMR spectroscopy with silica as a chiming agent to avoid field penetration limitations All phases except for LiSn exhibit exchanged NMR signals at room temperature for the various types of Li present in the unit cells. in the 10 to 100 ppm range. Electronic structure calculations based on first-principles method led to a lather good correlation between the participation of the Li 2s orbital to the density of states (DOS) at the Fermi level and the corresponding NMR Knight shift for the two Li crystallographic types in the case of LiSn, and for the weighted average of the different crystallographic types in the case of the NMR-exchanged signals for the other compounds |
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[Bekaert, Emilie; Menetrier, Michel] Univ Bordeaux, CNRS, ICMCB, F-33608 Pessac, France |
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AMER CHEMICAL SOC |
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1932-7447 |
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ISI:000276341700075 |
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EcoFoG @ eric.marcon @ |
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Leroy, C.; Carrias, J.-F.; Corbara, B.; Pélozuelo, L.; Dezerald, O.; Brouard, O.; Dejean, A.; Céréghino, R. |
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Mutualistic ants contribute to tank-bromeliad nutrition |
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Journal Article |
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2013 |
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Annals of Botany |
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Ann. Bot. |
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112 |
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5 |
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919-926 |
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δ15N; Algae; ants; Bromeliaceae; food webs; Formicinae; French Guiana; mutualistic interactions; nitrogen; phytotelmata; stable isotopes; tank bromeliad |
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Background and AimsEpiphytism imposes physiological constraints resulting from the lack of access to the nutrient sources available to ground-rooted plants. A conspicuous adaptation in response to that lack is the phytotelm (plant-held waters) of tank-bromeliad species that are often nutrient-rich. Associations with terrestrial invertebrates also result in higher plant nutrient acquisition. Assuming that tank-bromeliads rely on reservoir-assisted nutrition, it was hypothesized that the dual association with mutualistic ants and the phytotelm food web provides greater nutritional benefits to the plant compared with those bromeliads involved in only one of these two associations.MethodsQuantitative (water volume, amount of fine particulate organic matter, predator/prey ratio, algal density) and qualitative variables (ant-association and photosynthetic pathways) were compared for eight tank- and one tankless-bromeliad morphospecies from French Guiana. An analysis was also made of which of these variables affect nitrogen acquisition (leaf N and δ15N).Key ResultsAll variables were significantly different between tank-bromeliad species. Leaf N concentrations and leaf δ15N were both positively correlated with the presence of mutualistic ants. The amount of fine particulate organic matter and predator/prey ratio had a positive and negative effect on leaf δ15N, respectively. Water volume was positively correlated with leaf N concentration whereas algal density was negatively correlated. Finally, the photosynthetic pathway (C3 vs. CAM) was positively correlated with leaf N concentration with a slightly higher N concentration for C 3-Tillandsioideae compared with CAM-Bromelioideae.ConclusionsThe study suggests that some of the differences in N nutrition between bromeliad species can be explained by the presence of mutualistic ants. From a nutritional standpoint, it is more advantageous for a bromeliad to use myrmecotrophy via its roots than to use carnivory via its tank. The results highlight a gap in our knowledge of the reciprocal interactions between bromeliads and the various trophic levels (from bacteria to large metazoan predators) that intervene in reservoir-assisted nutrition. © The Author 2013. |
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CNRS, UMR 8172, Écologie des Forêts de Guyane, Campus Agronomique, F-97379 Kourou cedex, France |
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Export Date: 9 September 2013; Source: Scopus; Coden: Anboa; doi: 10.1093/aob/mct147; Language of Original Document: English; Correspondence Address: Leroy, C.; IRD, UMR AMAP (BotAnique et BioinforMatique de l'Architecture des Plantes), Boulevard de la Lironde, TA A-51/PS2, F-34398 Montpellier Cedex 5, France; email: celine.leroy@ird.fr |
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EcoFoG @ webmaster @ |
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501 |
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Brousseau, L.; Bonal, D.; Cigna, J.; Scotti, I. |
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Highly local environmental variability promotes intrapopulation divergence of quantitative traits: An example from tropical rain forest trees |
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Journal Article |
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2013 |
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Annals of Botany |
Abbreviated Journal |
Ann. Bot. |
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112 |
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6 |
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1169-1179 |
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common garden experiment; E. grandiflora; ecological traits; Eperua falcata; habitat mosaics; intrapopulation divergence; maternal family inheritance |
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Background and AimsIn habitat mosaics, plant populations face environmental heterogeneity over short geographical distances. Such steep environmental gradients can induce ecological divergence. Lowland rainforests of the Guiana Shield are characterized by sharp, short-distance environmental variations related to topography and soil characteristics (from waterlogged bottomlands on hydromorphic soils to well-drained terra firme on ferralitic soils). Continuous plant populations distributed along such gradients are an interesting system to study intrapopulation divergence at highly local scales. This study tested (1) whether conspecific populations growing in different habitats diverge at functional traits, and (2) whether they diverge in the same way as congeneric species having different habitat preferences.MethodsPhenotypic differentiation was studied within continuous populations occupying different habitats for two congeneric, sympatric, and ecologically divergent tree species (Eperua falcata and E. grandiflora, Fabaceae). Over 3000 seeds collected from three habitats were germinated and grown in a common garden experiment, and 23 morphological, biomass, resource allocation and physiological traits were measured.Key ResultsIn both species, seedling populations native of different habitats displayed phenotypic divergence for several traits (including seedling growth, biomass allocation, leaf chemistry, photosynthesis and carbon isotope composition). This may occur through heritable genetic variation or other maternally inherited effects. For a sub-set of traits, the intraspecific divergence associated with environmental variation coincided with interspecific divergence. Conclusions The results indicate that mother trees from different habitats transmit divergent trait values to their progeny, and suggest that local environmental variation selects for different trait optima even at a very local spatial scale. Traits for which differentiation within species follows the same pattern as differentiation between species indicate that the same ecological processes underlie intra- and interspecific variation. © 2013 The Author. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. |
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Université de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestières, Vandœuvre-lès-Nancy, France |
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Export Date: 17 October 2013; Source: Scopus; Coden: Anboa; doi: 10.1093/aob/mct176; Language of Original Document: English; Correspondence Address: Scotti, I.; INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou cedex, French Guiana; email: ivan.scotti@ecofog.gf |
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EcoFoG @ webmaster @ |
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505 |
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Vastra, M.; Salvin, P.; Roos, C. |
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MIC of carbon steel in Amazonian environment: Electrochemical, biological and surface analyses |
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2016 |
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International Biodeterioration and Biodegradation |
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International Biodeterioration and Biodegradation |
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112 |
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98-107 |
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Biology; Electrochemistry; Mic; Short term; Surface analyses |
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In this study, the corrosion of S355 carbon steel was monitored for 50 days in equatorial environment. The experiments were conducted under three complementary approaches in a natural environment: (i) bacterial diversity was assessed with Miseq sequencing, (ii) observations of the surface and identifications of deposit compounds were realised with scanning electron microscopy (SEM), Raman spectrometry and EDX analyses, (iii) electrochemical measurements were used to calculate corrosion rate and to identify the phenomena which control corrosion. The results showed that the bacterial population had changed over immersion time from a dominance of β-proteobacteria to α-proteobacteria. This evolution decreased charge transfer resistance at the metal/deposit from 41.6 to 20.8 Ω/cm2 in 50 days, caused an increase in the corrosion rate by a factor of 2, from 0.13 to 0.27 mm/year. Surface analyses showed a progressive appearance of MIC markers in the deposit such as iron sulphide and manganese oxides that were detected after 30 days of immersion in the natural environment. In conclusion, this study describes in detail, the first stage of MIC activity on carbon steel surface in an equatorial brackish water, under aerobic conditions. © 2016 Elsevier Ltd. |
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Laboratoire des Matériaux et Molécules en Milieu Agressif, Université des Antilles, UMR ECOFOG, Campus Universitaire, Schœlcher, Martinique |
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Export Date: 1 June 2016 |
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