Browsing by Issue Date, starting with "2019-08"
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- Sous l’emprise de l’anodin. Les vols commerciaux et la société contemporaine chez Jean EchenozPublication . Faria, DominiqueLe voyage, traditionnellement associé à l’exotisme et conçu comme une situation propice à la transformation personnelle, est décrit dans les romans de Jean Echenoz comme banal et sans effets, surtout lorsqu’il se fait en avion. Au début du voyage sont l’aéroport et l’intérieur de l’avion, des espaces devenus stériles, dénoués de singularité et d’identité. À la fin des périples, les contrées lointaines sont perçues comme des répliques de l’espace parisien que connaissent trop bien les protagonistes. Non seulement le vol raccourcit les distances, il manque aussi de durée, ce qui empêche toute mutation intérieure : lors de leur retour, les personnages constatent que rien n’a vraiment changé, aucune évolution psychologique, aucune modification des circonstances de leur vie n’a eu lieu. C’est dû à cette conception du voyage aérien que les dénouements des récits d’Echenoz renvoient souvent à la situation de départ : au mouvement (dans le temps et dans l’espace) ne correspond plus aucun changement.
- Species–area relationships in continuous vegetation : Evidence from Palaearctic grasslandsPublication . Dengler, Jürgen; Matthews, Thomas J.; Steinbauer, Manuel J.; Wolfrum, Sebastian; Boch, Steffen; Chiarucci, Alessandro; Conradi, Timo; Dembicz, Iwona; Marcenò, Corrado; García‐Mijangos, Itziar; Nowak, Arkadiusz; Storch, David; Ulrich, Werner; Campos, Juan Antonio; Cancellieri, Laura; Carboni, Marta; Ciaschetti, Giampiero; De Frenne, Pieter; Dolezal, Jiri; Dolnik, Christian; Essl, Franz; Fantinato, Edy; Filibeck, Goffredo; Grytnes, John‐Arvid; Guarino, Riccardo; Güler, Behlül; Janišová, Monika; Klichowska, Ewelina; Kozub, Łukasz; Kuzemko, Anna; Manthey, Michael; Mimet, Anne; Naqinezhad, Alireza; Pedersen, Christian; Peet, Robert K.; Pellissier, Vincent; Pielech, Remigiusz; Potenza, Giovanna; Rosati, Leonardo; Terzi, Massimo; Valkó, Orsolya; Vynokurov, Denys; White, Hannah; Winkler, Manuela; Biurrun, IdoiaAIM: Species-area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape. Location Palaearctic grasslands and other non-forested habitats. TAXA: Vascular plants, bryophytes and lichens. METHODS: We used the GrassPlot database, containing standardized vegetation-plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2,057 nested-plot series with at least seven grain sizes ranging from 1 cm(2) to 1,024 m(2). Using nonlinear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis-Menten). Based on AICc, we tested whether the ranking of functions differed among taxonomic groups, methodological settings, biomes or vegetation types. RESULTS: The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law. MAIN CONCLUSIONS: We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis-Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area.
- Environmental filtering underpins the island species : area relationship in a subtropical anthropogenic archipelagoPublication . Liu, Jinliang; Matthews, Thomas J.; Zhong, Lei; Liu, Jiajia; Wu, Donghao; Yu, MingjianNumerous mechanisms have been proposed to explain the island species-area relationship (ISAR), including the passive sampling effect, the habitat diversity effect, ecological drift and a group of mechanisms jointly termed environmental filtering (or abiotic selection process). However, determining which of these hypotheses underpins the ISAR in a given system remains an open and controversial question, particularly with regards to the environmental filtering. The effect of environmental filtering on the ISAR for woody plants was tested on 29 islands in a subtropical land-bridge archipelago. Island area had a significant effect on species richness, while isolation was not found to have an effect. After controlling for the passive sampling effect and habitat diversity using a systematic sampling design, we found that a positive ISAR remained. After controlling for island area and isolation, species richness was significantly affected by environmental conditions (e.g. total phosphorus, soil depth and bulk density). When a null model was used that randomly assigned individuals to islands from the regional pool, the difference between the observed and expected richness was greater for smaller islands relative to larger islands. Synthesis. Our results point to an overlooked role of environmental filtering in driving the island species-area relationship (ISAR). Consequently, our study highlights the importance of considering deterministic process in future analyses of the ISAR.
- Taxonomic divergence and functional convergence in Iberian spider forest communities : Insights from beta diversity partitioningPublication . Carvalho, José Carlos; Malumbres-Olarte, Jagoba; Arnedo, Miquel A.; Crespo, Luís C.; Domenech, Marc; Cardoso, PedroAIM: The main aims were to determine: (a) the relative contribution of species replacement and richness difference from components to overall taxonomic (TD beta) and functional (FD beta) beta diversity of spider communities; (b) the degree to which TD beta and FD beta components can be explained by the environmental or geographic predictors; (c) whether FD beta components were lower than expected given the underlying TD beta variation. LOCATION: This study was carried out in 22 oak forest sites across the Iberian Peninsula. The area comprises two biogeographic regions, Eurosiberian (North) and Mediterranean (Centre and South). METHODS: Spiders were sampled using a standardized protocol. A species x traits matrix was constructed. Total taxonomic (TD beta(total)) and total functional (FD beta(total)) beta diversity were calculated, by pairwise comparisons, and partitioned into their replacement (beta(repl)) and richness difference (beta(rich)) components. Mantel tests were used to relate taxonomic and functional dissimilarity with environmental and geographic distances. A spatial eigenfunction model was constructed and the variation in TD beta and FD beta explained by environment and geographic predictors was quantified. Null models were used to test if FD beta was higher or lower than expected given TD beta. RESULTS: beta(repl) was the dominant component contributing to 84.2% and 72.8% for TD beta(total) and FD beta(total), respectively. TD beta(total) and FD beta(total) (and their replacement components) were higher between- than within-biogeographic regions. TD beta(total) and TD beta(repl) were positively correlated with environmental and geographic distances, even when controlling for a biogeographic effect, but their functional counterparts were only correlated with environmental distance. Variation partitioning showed that pure environmental and spatially structured environmental effects had a small contribution to beta diversity, except for TD beta(rich). The observed slopes of the regressions of FD beta(total) and FD beta(repl) in relation to environmental distance were slower than the null model expectations. MAIN CONCLUSIONS: Spider assemblage variation was mainly determined by the replacement, and not the net loss, of species and traits. TD beta was influenced by niche filtering and dispersal limitation, whereas FD beta was mainly generated by niche filtering. A high level of functional convergence among spider communities, despite the high taxonomic divergence, revealed the signal of replacement of species performing similar functions across sites.
- Escrita feminina vs escrita feministaPublication . Gil, Ana Cristina Correia, dir.; Fialho, Adolfo Fernando da Fonte, ed.
- Fatty acid composition, TLC screening, ATR-FTIR analysis, anti-cholinesterase activity, and in vitro cytotoxicity to A549 tumor cell line of extracts of 3 macroalgae collected in MadeiraPublication . Nunes, Nuno; Rosa, Gonçalo P.; Ferraz, Sónia; Barreto, Maria do Carmo; Carvalho, Miguel A. A. Pinheiro deThree macroalgae collected at Madeira Island were included in this study to determine their potential for drug, nutraceutical, food, or supplement application. Fatty acid content was higher in Zonaria tournefortii (12.32 mg g⁻¹ dw) with 16.58% of PUFAs, eicosapentaenoic acid (C20:5 omega 3), and arachidonic acid (20:4 omega 6) having concentrations of 2.59 and 1.17%, respectively. The anti-thrombogenic and anti-atherogenicity potential was higher for Z. tournefortii due to relevant fatty acids in the biochemical composition this macroalgae. Lipid classes were assessed in the lipid extract and neutral lipids (NL) were in higher yield in Asparagopsis taxiformis (51.16%) and lower in Z. tournefortii (26.96%). The glycolipids (GL) were between 36.03 and 16.11% in Z. tournefortii and Ulva lactuca. Phospholipids (PL) fraction varied from 35.91 and 31.60% in A. taxiformis and Z. tournefortii. TLC screening identified that U. lactuca contains phytol and cholesterol in its NL, digalactosyldiacylglycerol in its GL, and cardiolipin and L-alpha-phosphatidylcholine in its PL. Zonaria tournefortii contains phytol and cholesterol in its NL classes, and the PL classes contain L-alpha-phosphatidylethanolamine and 1-(3-sn-phosphatidyl)-rac-glycerol. The macroalgae A. taxiformis revealed cholesterol in its NL fraction and the same phospholipids as Z. tournefortii in its PL fraction. ATR-FTIR analysis enabled a "fingerprint" spectra and important sulfation absorption bands were identified, revealing the functional polysaccharides within these macroalgae. Anti-cholinesterasic activity was assessed in A. taxiformis, with a low IC50 for AChE (8.92 +/- 0.43 mu g mL⁻¹) and BuChE (13.96 +/- 0.32 mu g mL⁻¹), demonstrating dual inhibitory activity, justifying the interest to identify the active principle which may be the scaffold of a novel drug.
- Uma permanência forçada em São Miguel : Marion Hartley na encruzilhada de identidadesPublication . Silva, Leonor Sampaio daA popularidade do tema da diáspora acentua-se numa época em que a mobilidade reaviva reflexões sobre identidade (Hall) e convida a discutir os nexos entre estado e nação (Safran). O artigo que se segue procura demonstrar como o tema da diáspora pode conviver com a literatura de viagens e infiltrar-se em universos textuais e sociais imprevistos, nomeadamente quando os viajantes são surpreendidos pelo rumo que toma a viagem que empreenderam. De igual modo, procurar-se-á relacionar a reflexão resultante do encontro de culturas com a importância do género epistolar para o autoconhecimento e a procura de integração social e de bem-estar pessoal. O ponto de partida é o conjunto de cartas escritas por Marion Hartley entre 1916 e 1919 a uma amiga americana. O enquadramento teórico baseia-se em reflexões sobre identidade no quadro dos encontros multiculturais e interculturais. Um dos objetivos é contribuir para repensar o conceito de diáspora, de modo a que ele inclua um leque mais alargado de experiências que ajudam a formar a consciência de si a partir de sentimentos de pertença e de exclusão vividos em contexto de viagem.