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Allié, E., Pélissier, R., Engel, J., Petronelli, P., Freycon, V., Deblauwe, V., et al. (2015). Pervasive local-scale tree-soil habitat association in a tropical forest community. PLoS ONE, 10(11), e0141488.
Abstract: We examined tree-soil habitat associations in lowland forest communities at Paracou, French Guiana.We analyzed a large dataset assembling six permanent plots totaling 37.5 ha, in which extensive LIDAR-derived topographical data and soil chemical and physical data have been integrated with precise botanical determinations. Map of relative elevation from the nearest stream summarized both soil fertility and hydromorphic characteristics, with seasonally inundated bottomlands having higher soil phosphate content and base saturation, and plateaus having higher soil carbon, nitrogen and aluminum contents. We employed a statistical test of correlations between tree species density and environmental maps, by generating Monte Carlo simulations of random raster images that preserve autocorrelation of the original maps. Nearly three fourths of the 94 taxa with at least one stem per ha showed a significant correlation between tree density and relative elevation, revealing contrasted species-habitat associations in term of abundance, with seasonally inundated bottomlands (24.5% of species) and well-drained plateaus (48.9% of species). We also observed species preferences for environments with or without steep slopes (13.8% and 10.6%, respectively). We observed that closely-related species were frequently associated with different soil habitats in this region (70% of the 14 genera with congeneric species that have a significant association test) suggesting species-habitat associations have arisen multiple times in this tree community. We also tested if species with similar habitat preferences shared functional strategies. We found that seasonally inundated forest specialists tended to have smaller stature (maximum diameter) than species found on plateaus. Our results underline the importance of tree-soil habitat associations in structuring diverse communities at fine spatial scales and suggest that additional studies are needed to disentangle community assembly mechanisms related to dispersal limitation, biotic interactions and environmental filtering from species-habitat associations. Moreover, they provide a framework to generalize across tropical forest sites. © 2015 Allié et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Cottet, K., Fromentin, Y., Kritsanida, M., Grougnet, R., Odonne, G., Duplais, C., et al. (2015). Isolation of Guttiferones from Renewable Parts of Symphonia globulifera by Centrifugal Partition Chromatography. Planta Medica, 81(17), 1604–1608.
Abstract: The aim of this study was to investigate the species Symphonia globulifera, a source of polycyclic polyprenylated acyl phloroglucinols such as guttiferone A, which is known to exhibit a variety of biological activities including noticeable antileishmanial properties. Our goal was the identification and the quantification of guttiferone A in different renewable parts of S. globulifera and its preparative isolation. To the best of our knowledge, there is no data concerning its mechanism of action. Consequently, it is particularly interesting to isolate it in gram quantities in order to establish structure activity relationship studies. After performing high-performance liquid chromatography profiles detecting the presence of guttiferone A and proceeding to its quantification, a centrifugal partition chromatography methodology using a two-phase solvent system of cyclohexane/ethyl acetate/methanol/water (20 : 1 : 20 : 1, v/v/v/v) was applied to each extract. In conclusion, a centrifugal partition chromatography system has been developed to ensure a fast, reliable, and scalable way to isolate, with a high level of purity, guttiferone A from five renewable parts of S. globulifera. Moreover, this methodology can be extended to the isolation of other polycyclic polyprenylated acyl phloroglucinols such as guttiferones B, C, and D. © Georg Thieme Verlag KG Stuttgart.
Keywords: centrifugal partition chromatography; Clusiaceae; countercurrent chromatography guttiferones; PPAPs; Symphonia globulifera
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Lenoir, A., Devers, S., Touchard, A., & Dejean, A. (2016). The Guianese population of the fire ant Solenopsis saevissima is unicolonial. Insect Science, 23(5), 739–745.
Abstract: In this study, conducted in French Guiana, a part of the native range of the fire ant Solenopsis saevissima, we compared the cuticular hydrocarbon profiles of media workers with previous results based on intraspecific aggressiveness tests. We noted a strong congruence between the two studies permitting us to delimit 2 supercolonies extending over large distances (up to 54 km), a phenomenon known as unicoloniality. Solenopsis geminata workers, taken as an out-group for cluster analyses, have a very different cuticular hydrocarbon profile. Because S. saevissima has been reported outside its native range, our conclusion is that this species has the potential to become invasive because unicoloniality (i.e., the main attribute for ants to become invasive) was shown at least for the Guianese population. © 2015 Institute of Zoology, Chinese Academy of Sciences
Keywords: biological invasions; cuticular hydrocarbons; fire ants; unicoloniality
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Pavoine, S., Marcon, E., & Ricotta, C. (2016). ‘Equivalent numbers’ for species, phylogenetic or functional diversity in a nested hierarchy of multiple scales. Methods in Ecology and Evolution, 7(10), 1152–1163.
Abstract: Many recent studies have searched to integrate species’ functions and phylogenies in the measurement of biodiversity. To obtain easily interpretable measures, some researchers recommended diversity indices expressed in terms of equivalent numbers of species: the number of equally likely and maximally dissimilar species needed to produce the given value of diversity. Then, biodiversity is often calculated at three scales: within communities (α diversity), among communities (β diversity) and in a region (γ diversity). These three scales are, however, insufficient to tackle the organization of biodiversity in space because, for most organisms, there is a nested hierarchy of multiple scales characterized by different patterns and processes, from the small neighbourhood to the biosphere. We developed methodologies for analysing species, functional, taxonomic or phylogenetic diversity in a hierarchy of multiple scales using equivalent numbers of species. As an example, we analysed the taxonomic and functional diversity of macroinvertebrate assemblages in the Loire River, France, at four levels: within sites (α diversity), among sites within geological regions (β1 diversity), among geological regions (β2 diversity) and at the river scale (γ diversity). The new hierarchical approaches of biodiversity revealed very low differences among sites within regions and among regions in terms of taxonomy and functional traits (size and diet), despite moderate, significant species turnover among geological regions. We compare our framework with those other authors have developed. We argue that different definitions of α, β, γ diversities are used in the literature reflecting different points of view on biodiversity. We make recommendations on how to normalize functional (or phylogenetic) dissimilarities among species to render sites and regions comparable, and discuss the pros and cons of our approach. The hierarchical approaches of biodiversity in terms of ‘equivalent numbers’ respond to current demands to obtain intuitive, easily interpretable components of biodiversity. The approaches we propose go beyond current developments by considering a hierarchy of spatial scales and unbalanced sampling design. They will provide powerful tools to detect the ecological and evolutionary processes that act differently at different scales. © 2016 The Authors. Methods in Ecology and Evolution © 2016 British Ecological Society
Keywords: alpha diversity; beta diversity; biodiversity; community ecology; community phylogenetics; diversity apportionment; gamma diversity; quadratic entropy
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Verheyen, K., Vanhellemont, M., Auge, H., Baeten, L., Baraloto, C., Barsoum, N., et al. (2016). Contributions of a global network of tree diversity experiments to sustainable forest plantations. Ambio, 45(1), 29–41.
Abstract: The area of forest plantations is increasing worldwide helping to meet timber demand and protect natural forests. However, with global change, monospecific plantations are increasingly vulnerable to abiotic and biotic disturbances. As an adaption measure we need to move to plantations that are more diverse in genotypes, species, and structure, with a design underpinned by science. TreeDivNet, a global network of tree diversity experiments, responds to this need by assessing the advantages and disadvantages of mixed species plantations. The network currently consists of 18 experiments, distributed over 36 sites and five ecoregions. With plantations 1–15 years old, TreeDivNet can already provide relevant data for forest policy and management. In this paper, we highlight some early results on the carbon sequestration and pest resistance potential of more diverse plantations. Finally, suggestions are made for new, innovative experiments in understudied regions to complement the existing network. © 2015, Royal Swedish Academy of Sciences.
Keywords: Biodiversity experiments; Ecological restoration; Functional biodiversity research; Plantation forest; Sustainable forest management
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Kunstler, G., Falster, D., Coomes, D. A., Hui, F., Kooyman, R. M., Laughlin, D. C., et al. (2016). Plant functional traits have globally consistent effects on competition. Nature, 529(7585), 204–207.
Abstract: Phenotypic traits and their associated trade-offs have been shown to have globally consistent effects on individual plant physiological functions, but how these effects scale up to influence competition, a key driver of community assembly in terrestrial vegetation, has remained unclear. Here we use growth data from more than 3 million trees in over 140,000 plots across the world to show how three key functional traits – wood density, specific leaf area and maximum height – consistently influence competitive interactions. Fast maximum growth of a species was correlated negatively with its wood density in all biomes, and positively with its specific leaf area in most biomes. Low wood density was also correlated with a low ability to tolerate competition and a low competitive effect on neighbours, while high specific leaf area was correlated with a low competitive effect. Thus, traits generate trade-offs between performance with competition versus performance without competition, a fundamental ingredient in the classical hypothesis that the coexistence of plant species is enabled via differentiation in their successional strategies. Competition within species was stronger than between species, but an increase in trait dissimilarity between species had little influence in weakening competition. No benefit of dissimilarity was detected for specific leaf area or wood density, and only a weak benefit for maximum height. Our trait-based approach to modelling competition makes generalization possible across the forest ecosystems of the world and their highly diverse species composition. © 2016 Macmillan Publishers Limited. All rights reserved.
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Rodríguez-Pérez, H., Hilaire, S., & Mesléard, F. (2016). Temporary pond ecosystem functioning shifts mediated by the exotic red swamp crayfish (Procambarus clarkii): a mesocosm study. Hydrobiologia, 767(1), 333–345.
Abstract: Temporary ponds, acknowledged for their conservation value, are colonized by the invasive crayfish Procambarus clarkii. We have tested the consequences of this colonization for the ecosystem under two contrasted scenarios: one single individual arrival or three individuals arrival. We recreated the temporary pond ecosystem in 1 m2 tanks to investigate the impact of the two crayfish densities. We studied the macrophyte community composition and abundance, chlorophyll a and total suspended solids concentrations, and the diversity and functional composition of micro-crustacean and macro-invertebrate communities. We observed a reduction of macrophyte biomass in experimental crayfish mesocosms in comparison with control tanks, nearly 80 and 40% less in 3 and 1 crayfish/m2 tanks, respectively. The macrophyte community shifted, followed by a filamentous algae development, an increase of bare sediment and turbidity in crayfish tanks. The macro-invertebrate community suffered a richness loss of 28 and 22%, in 3 and 1 crayfish/m2 tanks, respectively. Functionally, macro-invertebrate diversity reduction most strongly affected the grazer, detritivore and predator trophic groups. Microcrustaceans seemed not to be affected by the introduction of the crayfish. The introduction of the crayfish greatly altered the ecosystem structure and subsequently the ecosystem functioning. © 2015, Springer International Publishing Switzerland.
Keywords: Ecosystem functioning; Exotic crayfish; Procambarus clarkii; Temporary pond
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Touchard, A., Aili, S. R., Fox, E. G. P., Escoubas, P., Orivel, J., Nicholson, G. M., et al. (2016). The biochemical toxin arsenal from ant venoms. Toxins, 8(1), 30.
Abstract: Ants (Formicidae) represent a taxonomically diverse group of hymenopterans with over 13,000 extant species, the majority of which inject or spray secretions from a venom gland. The evolutionary success of ants is mostly due to their unique eusociality that has permitted them to develop complex collaborative strategies, partly involving their venom secretions, to defend their nest against predators, microbial pathogens, ant competitors, and to hunt prey. Activities of ant venom include paralytic, cytolytic, haemolytic, allergenic, pro-inflammatory, insecticidal, antimicrobial, and pain-producing pharmacologic activities, while non-toxic functions include roles in chemical communication involving trail and sex pheromones, deterrents, and aggregators. While these diverse activities in ant venoms have until now been largely understudied due to the small venom yield from ants, modern analytical and venomic techniques are beginning to reveal the diversity of toxin structure and function. As such, ant venoms are distinct from other venomous animals, not only rich in linear, dimeric and disulfide-bonded peptides and bioactive proteins, but also other volatile and non-volatile compounds such as alkaloids and hydrocarbons. The present review details the unique structures and pharmacologies of known ant venom proteinaceous and alkaloidal toxins and their potential as a source of novel bioinsecticides and therapeutic agents. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
Keywords: Alkaloids; Ant venom; Enzymes; Formic acid; Peptides; Toxins; Venom biochemistry
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Doughty, C. E., Wolf, A., Baraloto, C., & Malhi, Y. (2016). Interdependency of plants and animals in controlling the sodium balance of ecosystems and the impacts of global defaunation. Ecography, 39(2), 204–212.
Abstract: Sodium, an element which is needed by animals but often toxic in high concentrations to plants, may be deficient and limit animal abundance in inland continental regions, but may be overabundant and limit plant productivity in coastal regions. Here we present data from 50 independent plots (including leaf data from more than 2480 individual trees) showing that leaves in the Amazon basin uptake high amounts of sodium (Na) in a manner more similar to the essential cation potassium (K) than to the toxic cation aluminium (Al). Leaf Na increases linearly with soil Na concentrations, and there is no apparent mechanism for selective exclusion of Na in comparison to K, a key attribute of halophytes. This indicates that the Amazon basin is broadly non-halophytic and increased sodium concentrations in non-halophyte plants often decrease plant productivity. Total Na concentrations are ∼ 10 times higher in coastal regions than inland regions. Such concentration gradients in nutrients may have been reduced in the past because large animals that were abundant in the Pleistocene have been hypothesized to play a large role in reducing nutrient concentration gradients at continental scales. We use a diffusion model and a Na loss rate based on empirical data to estimate that large animals may have moved significant quantities of Na inland away from coastal regions in the Amazon Basin. Therefore, our simple model suggests that large animals may play an important, yet diminishing, role in maintaining the sodium balance of the planet. © 2016 Nordic Society Oikos.
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Roy, M., Schimann, H., Braga-Neto, R., Da Silva, R. A. E., Duque, J., Frame, D., et al. (2016). Diversity and Distribution of Ectomycorrhizal Fungi from Amazonian Lowland White-sand Forests in Brazil and French Guiana. Biotropica, 48(1), 90–100.
Abstract: White-sand forests are thought to host many ectomycorrhizal fungi, as demonstrated by the numerous fruiting body collections made by Rolf Singer in the lower Rio Negro in the late 1970s. Despite recognition of the importance of ectomycorrhizal fungi in white-sand forests, there has not yet been a systematic examination of diversity and taxonomic composition across white-sand forests, or more widely across lowland Amazonian forests. In an effort to broaden our view of ectomycorrhizal fungal diversity and distribution on white-sand forests, we collected ectomycorrhizal fruiting bodies in 10 plots of white-sand forests in Brazil and French Guiana between 2012 and 2014. We collected 221 specimens and 62 morphospecies, from the 10 plots, confirming that all studied white-sand forests host ectomycorrhizal fungi. Additionally, we searched for taxa associated with white sands among specimens deposited in Brazilian herbaria. We report 1006 unique ectomycorrhizal specimen records in 18 Brazilian herbaria, of which 137 specimens and 64 species are reported from white-sand forests, mainly in the state of Amazonas, Brazil. Russulaceae and Amanitaceae were frequent in all habitats, and Cortinarius were more frequent on white sands. Our results highlight the high diversity and heterogeneity of ectomycorrhizal communities on white-sand forests, and the wide distribution of ectomycorrhizal fungi throughout Brazil, irrespective of soil type. © 2016 The Association for Tropical Biology and Conservation.
Keywords: campina; campinarana; Amanitaceae; Amanitaceae; Boletaceae; Boletaceae; Campina; Campinarana; Herbarium; Herbário; Russulaceae; Russulaceae
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