Résumé
Aim Although soil biodiversity is extremely rich and spatially variable, both in terms of species and trophic groups, we still know little about its main drivers. Here, we contrast four long-standing hypotheses to explain the spatial variation of soil multi-trophic diversity: energy, physiological tolerance, habitat heterogeneity and resource heterogeneity. Location French Alps. Methods We built on a large-scale observatory across the French Alps (Orchamp) made of seventeen elevational gradients ( 90 plots) ranging from low to very high altitude (280–3,160 m), and encompassing large variations in climate, vegetation and pedological conditions. Biodiversity measurements of 36 soil trophic groups were obtained through environmental DNA metabarcoding. Using a machine learning approach, we assessed (1) the relative importance of predictors linked to different ecological hypotheses in explaining overall multi-trophic soil biodiversity and (2) the consistency of the response curves across trophic groups. Results We showed that predictors associated with the four hypotheses had a statistically significant influence on soil multi-trophic diversity, with the strongest support for the energy and physiological tolerance hypotheses. Physiological tolerance explained spatial variation in soil diversity consistently across trophic groups, and was an especially strong predictor for bacteria, protists and microfauna. The effect of energy was more group-specific, with energy input through soil organic matter strongly affecting groups related to the detritus channel. Habitat and resource heterogeneity had overall weaker and more specific impacts on biodiversity with habitat heterogeneity affecting mostly autotrophs, and resource heterogeneity affecting bacterivores, phytophagous insects, enchytraeids and saprotrophic fungi. Main Conclusions Despite the variability of responses to the environmental drivers found across soil trophic groups, major commonalities on the ecological processes structuring soil biodiversity emerged. We conclude that among the major ecological hypotheses traditionally applied to aboveground organisms, some are particularly relevant to predict the spatial variation in soil biodiversity across the major soil trophic groups.
Auteurs, date et publication :
Auteurs Irene Calderón-Sanou , Lucie Zinger , Mickael Hedde , Camille Martinez-Almoyna , Amelie Saillard , Julien Renaud , Ludovic Gielly , Norine Khedim , Clement Lionnet , Marc Ohlmann , Orchamp Consortium , Tamara Münkemüller , Wilfried Thuiller
Publication : Diversity and Distributions
Date : 2025
Volume : 28
Issue : 12
Pages : 2549-2564
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Intraspecific competition at the larval stage is an important ecological factor affecting life-history, adaptation and evolutionary trajectory in holometabolous insects. However, the molecular pathways underpinning these ecological processes are poorly characterized. We reared Drosophila melanogaster at three egg densities (5, 60, and 300 eggs/mL) and sequenced the transcriptomes of pooled third-instar larvae. We also examined emergence time, egg-to-adult viability, adult mass, and adult sex-ratio at each density. Medium crowding had minor detrimental effects on adult phenotypes compared to low density and yielded 24 differentially expressed genes (DEGs), including several chitinase enzymes. In contrast, high crowding had substantial detrimental effects on adult phenotypes and yielded 2107 DEGs. Among these, upregulated gene sets were enriched in sugar, steroid and amino acid metabolism as well as DNA replication pathways, whereas downregulated gene sets were enriched in ABC transporters, taurine, Toll/Imd signaling, and P450 xenobiotics metabolism pathways. Overall, our findings show that larval crowding has a large consistent effect on several molecular pathways (i.e., core responses) with few pathways displaying density-specific regulation (i.e., idiosyncratic responses). This provides important insights into how holometabolous insects respond to intraspecific competition during development.
Auteurs, date et publication :
Auteurs Juliano Morimoto , Marius Wenzel , Davina Derous , Youn Henry , Herve Colinet
Publication : Insect Science
Date : 2025
Volume : n/a
Issue : n/a
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
Ecological interactions are being affected at unprecedented rates by human activities in tropical forests. Yet, the continuity of ecological functions provided by animals, such as seed dispersal, is crucial for forest regeneration and species resilience to anthropogenic pressures. The construction of new roads in tropical forests is one of the main boosters of habitat destruction as it facilitates human access to previously isolated areas and increases defaunation and loss of ecological functions. It, therefore, becomes increasingly urgent to rapidly assess how recently opened roads and associated anthropogenic activities affect ecological processes in natural habitats, so that appropriate management measures to conserve diversity can be taken. In this study, we aimed to evaluate the effects of anthropogenic pressures on the health status of a mature rainforest crossed by a newly opened road in French Guiana. For this, we combined different methods to conduct a rapid assessment of the forest’s health status. Firstly, we evaluated the activity of frugivores using camera traps deployed in four forest patches located near (<1 km) ecological corridors preserved as canopy bridges over the road during the fruiting periods of four animal-dispersed tree species. Secondly, we analyzed the fate of seeds enclosed in animal-dispersed tropical fruits by calculating the proportions of fruits consumed and seeds removed (either dispersed or predated) by frugivores. Results show that the proportion of fruits opened and consumed was lower in the forest areas located near the road than in the control forest, and this difference was more significant for plant species strictly dependent on large-bodied primates for seed dispersal than for species relying on both primates and birds. Camera traps showed the presence of small primates and kinkajous feeding on Virola fruits in the forest impacted by the road, where large primates were absent. It is thus likely that smaller frugivores exert a compensatory effect that maintains ecological functions near the road. Despite efforts made to preserve forest continuity through ecological corridors, anthropogenic pressures associated with road proximity are affecting wildlife and disrupting associated ecological functions crucial for plant regeneration, contributing to further forest degradation.
Auteurs, date et publication :
Auteurs Opale Coutant , Olivier Boissier , Manon Ducrettet , Aurélie Albert-Daviaud , Axelle Bouiges , Caroline Marques Dracxler , François Feer , Irene Mendoza , Eric Guilbert , Pierre-Michel Forget
Publication : Frontiers in Ecology and Evolution
Date : 2025
Volume : 10
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Current theory predicts that the intensity of biotic interactions, particularly herbivory, decreases with increasing latitude and elevation. However, recent studies have revealed substantial variation in both the latitudinal and elevational patterns of herbivory. This variation is often attributed to differences in study design and the type of data collected by different researchers. Here, we used a similar sampling protocol along elevational gradients in six mountain ranges, located at different latitudes within temperate Eurasia, to uncover the sources of variation in elevational patterns in insect herbivory on woody plant leaves. We discovered a considerable variation in elevational patterns among different mountain ranges; nevertheless, herbivory generally decreased with increasing elevation at both the community-wide and individual plant species levels. This decrease was mostly due to openly living defoliators, whereas no significant association was detected between herbivory and elevation among insects living within plant tissues (i.e., miners and gallers). The elevational decrease in herbivory was significant for deciduous plants but not for evergreen plants, and for tall plants but not for low-stature plants. The community-wide herbivory increased with increases in both specific leaf area and leaf size. The strength of the negative correlation between herbivory and elevation increased from lower to higher latitudes. We conclude that despite the predicted overall decrease with elevation, elevational gradients in herbivory demonstrate considerable variation, and this variation is mostly associated with herbivore feeding habits, some plant traits, and latitude of the mountain range.
Auteurs, date et publication :
Auteurs Mikhail V. Kozlov , Vitali Zverev , Elena L. Zvereva
Publication : Ecology and Evolution
Date : 2025
Volume : 12
Issue : 11
Pages : e9468
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Many anuran species remain to be formally named and described in Amazonia, notably in the Guiana Shield, and particularly in megadiverse groups such as Pristimantis. Several species in the Guiana Shield region have been confused with Pristimantis marmoratus and P. ockendeni. Hylodes grandoculis, a taxon previously placed in the synonymy of P. marmoratus, may be available for one of these species. To disentangle this confusing situation, we examined the external morphology and osteology (via µ-CT scans) of the holotype of H. grandoculis, the holotype of Pristimantis marmoratus, and of recently collected material for which we also analyzed molecular, acoustic, and morphological variation. We concluded that some populations from Suriname and northern Pará, Brazil, are distinct from P. marmoratus and correspond to Pristimantis grandoculis. Other populations, from French Guiana, are closely related to P. grandoculis but their status remains ambiguous. Finally, some populations, from French Guiana and Amapá, Brazil, are conspicuously distinct from both P. marmoratus and P. grandoculis and are described herein as P. crepitaculus sp. nov. A third species, belonging to a “trans-amazon complex”, occurs in southern Suriname, Guyana, and Brazil and remains undescribed. Pristimantis grandoculis and related populations from French Guiana lack external tympanum, columella, pharyngeal ostia, vocal slits and do not vocalize. This represents a rare, perhaps unique, example of a deaf and mute species of frogs from the Amazonian lowlands.
Auteurs, date et publication :
Auteurs Antoine Fouquet , Pedro Peloso , Rawien Jairam , Albertina P. Lima , Alexander T. Mônico , Raffael Ernst , Philippe J. R. Kok
Publication : Organisms Diversity & Evolution
Date : 2025
Volume : 22
Issue : 4
Pages : 1065-1098
Catégorie(s)
#CNRS #FORET NouraguesRésumé
The biogeography of neotropical fungi remains poorly understood. Here, we reconstruct the origins and diversification of neotropical lineages in one of the largest clades of ectomycorrhizal fungi in the globally widespread family Russulaceae.
Auteurs, date et publication :
Auteurs Jan Hackel , Terry W. Henkel , Pierre‐Arthur Moreau , Eske De Crop , Annemieke Verbeken , Mariana Sà , Bart Buyck , Maria‐Alice Neves , Aída Vasco‐Palacios , Felipe Wartchow , Heidy Schimann , Fabian Carriconde , Sigisfredo Garnica , Régis Courtecuisse , Monique Gardes , Sophie Manzi , Eliane Louisanna , Mélanie Roy
Publication : New Phytologist
Date : 2025
Volume : 236
Issue : 2
Pages : 698-713
Catégorie(s)
#CNRS #FORET NouraguesRésumé
We here establish a new genus in the nymphalid butterfly subtribe Euptychiina, Cisandina Nakahara & Espeland, n. gen. to harbor five species hitherto placed within two polyphyletic genera, namely Magneuptychia Forster, 1964 and Euptychoides Forster, 1964. We compiled data from over 350 specimens in 17 public and private collections, as well as DNA sequence data for all relevant species, to revise the species-level classification of this new genus. According to our multi-locus molecular phylogeny estimated with the maximum likelihood approach, Cisandina lea n. comb., Cisandina philippa n. comb. & reinst. stat., Cisandina fida n. comb., Cisandina sanmarcos n. comb., and Cisandina trinitensis n. comb. are proposed as new taxonomic combinations, since these species are distantly related to the type species of Magneuptychia and Euptychoides and cannot reasonably be accommodated in any other genus. Lectotypes are designated for Papilio lea Cramer, 1777, Papilio junia Cramer, 1780, Euptychia philippa Butler, 1867, and Eupytchia fida Weymer, 1911. Two new species of Cisandina n. gen. are named and described herein, C. esmeralda Nakahara & Barbosa, n. sp. and C. castanya Lamas & Nakahara, n. sp., increasing the described species diversity of the genus to seven. The immature stages of C. castanya n. sp. and C. philippa n. comb. & reinst. stat. are documented along with their natural hostplants, representing the first two species of the genus with known life history information. We describe a new subspecies, Cisandina fida directa Nakahara & Willmott, n. ssp., based on a limited number of specimens from southern Ecuador and central Peru. We were unable to obtain genetic data for the nominate race of C. fida n. comb., and thus, this taxonomic hypothesis is currently based solely on phenotypic characters.
Auteurs, date et publication :
Auteurs Shinichi Nakahara , Maryzender Rodríguez-Melgarejo , Kaylin Kleckner , Thalia Corahua-Espinoza , Rafael Tejeira , Marianne Espeland , Mirna M Casagrande , Eduardo P Barbosa , Joseph See , Geoffrey Gallice , Gerardo Lamas , Keith R Willmott , Marko Mutanen
Publication : Insect Systematics and Diversity
Date : 2022
Volume : 6
Issue : 1
Pages : 2
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Organic matter management is key to sustain ecosystem services provided by soils. However, it is rarely considered in a holistic view, considering local resources, agro-environmental effects and harmonization with farmers’ needs. Organic inputs, like compost and biochar, could represent a sustainable solution to massive current challenges associated to the intensification of agriculture, in particular for tropical regions. Here we assess the potential of agricultural residues as a resource for farmer communities in southwestern India to reduce their dependency on external inputs and sustain ecosystem services. We propose a novel joint evaluation of farmers’ aspirations together with agro-environmental effects of organic inputs on soils. Our soil quality evaluation showed that biochar alone or with compost did not improve unilaterally soils in the tropics (Anthroposol, Ferralsol and Vertisol). Many organic inputs led to an initial decrease in water-holding capacities of control soils (-27.3%: coconut shell biochar with compost on Anthroposol). Responses to organic matter inputs for carbon were strongest for Ferralsols (+33.4% with rice husk biochar), and mostly positive for Anthroposols and Vertisols (+12.5% to +13.8% respectively). Soil pH responses were surprisingly negative for Ferralsols and only positive if biochar was applied alone (between -5.6% to +1.9%). For Anthroposols and Vertisols, highest increases were achieved with rice husk biochar + vermicomposts (+7.2% and +5.2% respectively). Our socio-economic evaluation showed that farmers with a stronger economical position showed greater interest towards technology like biochar (factor 1.3 to 1.6 higher for farmers cultivating Anthroposols and/or Vertisols compared to Ferralsols), while poorer farmers more skepticism, which may lead to an increased economical gap within rural communities if technologies are not implemented with long-term guidance. These results advocate for an interdisciplinary evaluation of agricultural technology prior to its implementation as a development tool in the field.
Auteurs, date et publication :
Auteurs Severin-Luca Bellè , Jean Riotte , Norman Backhaus , Muddu Sekhar , Pascal Jouquet , Samuel Abiven
Publication : PLOS ONE
Date : 2022
Volume : 17
Issue : 1
Pages : e0263302
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Abstract. Terrestrial biosphere models typically use the biochemical model of Farquhar, von Caemmerer, and Berry (1980) to simulate photosynthesis, which requires accurate values of photosynthetic capacity of different biomes. However, data on tropical forests are sparse and highly variable due to the high species diversity, and it is still highly uncertain how these tropical forests respond to nutrient limitation in terms of C uptake. Tropical forests often grow on soils low in phosphorus (P) and are, in general, assumed to be P rather than nitrogen (N) limited. However, the relevance of P as a control of photosynthetic capacity is still debated. Here, we provide a comprehensive dataset of vertical profiles of photosynthetic capacity and important leaf traits, including leaf N and P concentrations, from two 3-year, large-scale nutrient addition experiments conducted in two tropical rainforests in French Guiana. These data present a unique source of information to further improve model representations of the roles of N, P, and other leaf nutrients in photosynthesis in tropical forests. To further facilitate the use of our data in syntheses and model studies, we provide an elaborate list of ancillary data, including important soil properties and nutrients, along with the leaf data. As environmental drivers are key to improve our understanding of carbon (C) and nutrient cycle interactions, this comprehensive dataset will aid to further enhance our understanding of how nutrient availability interacts with C uptake in tropical forests. The data are available at https://doi.org/10.5281/zenodo.5638236 (Verryckt, 2021).
Auteurs, date et publication :
Auteurs Lore T. Verryckt , Sara Vicca , Leandro Van Langenhove , Clément Stahl , Dolores Asensio , Ifigenia Urbina , Romà Ogaya , Joan Llusià , Oriol Grau , Guille Peguero , Albert Gargallo-Garriga , Elodie A. Courtois , Olga Margalef , Miguel Portillo-Estrada , Philippe Ciais , Michael Obersteiner , Lucia Fuchslueger , Laynara F. Lugli , Pere-Roc Fernandez-Garberí , Helena Vallicrosa
Publication : Earth System Science Data
Date : 2022
Volume : 14
Issue : 1
Pages : 5-18
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Production, emission, and absorption of biogenic volatile organic compounds (BVOCs) in ecosystem soils and associated impacts of nutrient availability are unclear; thus, predictions of effects of global change on source-sink dynamic under increased atmospheric N deposition and nutrition imbalances are limited. Here, we report the dynamics of soil BVOCs under field conditions from two undisturbed tropical rainforests from French Guiana. We analyzed effects of experimental soil applications of nitrogen (N), phosphorus (P), and N + P on soil BVOC exchanges (in particular of total terpenes, monoterpenes, and sesquiterpenes), to determine source and sink dynamics between seasons (dry and wet) and elevations (upper and lower elevations corresponding to top of the hills (30 m high) and bottom of the valley). We identified 45 soil terpenoids compounds emitted to the atmosphere, comprising 26 monoterpenes and 19 sesquiterpenes; of these, it was possible to identify 13 and 7 compounds, respectively. Under ambient conditions, soils acted as sinks of these BVOCs, with greatest soil uptake recorded for sesquiterpenes at upper elevations during the wet season (-282 μg m-2 h-1). Fertilization shifted soils from a sink to source, with greatest levels of terpene emissions recorded at upper elevations during the wet season, following the addition of N (monoterpenes: 406 μg m-2 h-1) and P (sesquiterpenes: 210 μg m-2 h-1). Total soil terpene emission rates were negatively correlated with total atmospheric terpene concentrations. These results indicate likely shifts in tropical soils from sink to source of atmospheric terpenes under projected increases in N deposition under global change, with potential impacts on regional-scale atmospheric chemistry balance and ecosystem function.
Auteurs, date et publication :
Auteurs Joan Llusià , Dolores Asensio , Jordi Sardans , Iolanda Filella , Guille Peguero , Oriol Grau , Romà Ogaya , Albert Gargallo-Garriga , Lore T. Verryckt , Leandro Van Langenhove , Laëtitia M. Brechet , Elodie Courtois , Clément Stahl , Ivan A. Janssens , Josep Peñuelas
Publication : Science of The Total Environment
Date : 2022
Volume : 802
Pages : 149769