Résumé
The outstanding species richness of Amazonia has fascinated biologists for centuries. However, the records of actual numbers and distribution of species forming its ecosystems are so incomplete that the understanding of the historical causes and regional determinants of this diversity remain speculative. Anuran clades have repeatedly been documented to harbour many unnamed species in this region, notably the Boana albopunctata species group. Considering the documented distribution and the ecology of the species of that group, we hypothesized that it diversified via successive trans-riverine dispersals during the late Miocene and Pliocene, after the formation of the modern Amazon watershed. To test this hypothesis, we gathered an extensive dataset of 16S rDNA sequences sampled throughout Amazonia and a mitogenomic dataset representative of the diversity of the Glade to (1) re-evaluate species boundaries and distributions, and (2) infer the spatio-temporal history of diversification within Amazonia. We delimited 14 Operational Taxonomic Units (OTUs) in an Amazonian Glade, i.e., 75% higher than currently recognized (14 OTUs for eight described species). Combining molecular data with morphological and acoustic data, two new species, Boana courtoisae sp. nov. from the eastern Guiana Shield and Boana eucharis sp. nov. from Southern Amazonia, are described herein. These species belong to a Glade that diversified throughout Amazonia during the last 10 Ma, thus more recently than co-distributed small terrestrial anurans but concomitantly with other more vagile vertebrates. Our time-scaled phylogeny and biogeographic analyses suggest an initial east-west divergence and confirm reciprocal trans-riverine dispersals during the last 5 Ma. The geomorphological evolution of the region and species-specific dispersal ability largely explain these distinct spatio-temporal patterns across anurans. http://www.zoobank.org/zoobank.org:act:4F8ACA9F-F6F1-4605-BD6C-6D4650AAC CBE http://www.zoobank.org/zoobank.org:act:51CC7B40-2D6B-4A9E-AF50-AB34D4CE1 042
Auteurs, date et publication :
Auteurs Antoine Fouquet , Pedro Marinho , Alexandre Rejaud , Thiago R. Carvalho , Marcel A. Caminer , Martin Jansen , Raissa N. Rainha , Miguel T. Rodrigues , Fernanda P. Werneck , Albertina P. Lima , Tomas Hrbek , Ariovaldo A. Giaretta , Pablo J. Venegas , German Chavez , Santiago Ron
Publication : SYSTEMATICS AND BIODIVERSITY
Date : 2021
Volume : 19
Issue : 4
Pages : 375-399
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesRésumé
Rice poses a major source of the toxic contaminant cadmium (Cd) for humans. Here, we elucidated the role of Cd storage forms (i.e., the chemical Cd speciation) on the dynamics of Cd within rice. In a pot trial, we grew rice on a Cd-contaminated soil in upland conditions and sampled roots and shoots parts at flowering and maturity. Cd concentrations, isotope ratios, Cd speciation (X-ray absorption spectroscopy), and micronutrient concentrations were analyzed. During grain filling, Cd and preferentially light Cd isotopes were strongly retained in roots where the Cd storage form did not change (Cd bound to thiols, Cd-S = 100%). In the same period, no net change of Cd mass occurred in roots and shoots, and the shoots became enriched in heavy isotopes (Delta Cd-114/110(maturity-flowering) = 0.14 +/- 0.04 parts per thousand). These results are consistent with a sequestration of Cd in root vacuoles that includes strong binding of Cd to thiol containing ligands that favor light isotopes, with a small fraction of Cd strongly enriched in heavy isotopes being transferred to shoots during grain filling. The Cd speciation in the shoots changed from predominantly Cd-S (72%) to Cd bound to O ligands (Cd-O, 80%) during grain filling. Cd-O may represent Cd binding to organic acids in vacuoles and/or binding to cell walls in the apoplast. Despite this change of ligands, which was attributed to plant senescence, Cd was largely immobile in the shoots since only 0.77% of Cd in the shoots were transferred into the grains. Thus, both storage forms (Cd-S and Cd-O) contributed to the retention of Cd in the straw. Cd was mainly bound to S in nodes I and grains (Cd-S > 84%), and these organs were strongly enriched in heavy isotopes compared to straw (Delta Cd-114/110(grains/nodes-)straw = 0.66-0.72 parts per thousand) and flag leaves (Delta Cd-114/110(grains/nodes-flag leaves) = 0.49-0.52 parts per thousand). Hence, xylem to phloem transfer in the node favors heavy isotopes, and the Cd-S form may persist during the transfer of Cd from node to grain. This study highlights the importance of Cd storage forms during its journey to grain and potentially into the food chain.
Auteurs, date et publication :
Auteurs Matthias Wiggenhauser , Anne-Marie Aucour , Philippe Telouk , Hester Blommaert , Geraldine Sarret
Publication : FRONTIERS IN PLANT SCIENCE
Date : 2021
Volume : 12
Catégorie(s)
#ANR-Citation #CNRS #Lautaret #UGARésumé
Microorganisms associated with plants are determinant for their fitness, but also in the case of vine grapes, for the quality and quantity of the wine. Plant microbiota is, however highly variable in space despite deterministic recruitment from the soil reservoir. Therefore, understanding the drivers that shape this microbiota is a key issue. Most studies that have analysed microorganisms associated with vines have been conducted at large scales (e.g., over 100 km) and have analysed the bulk soil and the rhizosphere. In this study, we focused on the root-microbiota endosphere, the most intimate fraction of microorganisms associated with plants. We sampled vine roots in 37 fields distributed throughout a vineyard to investigate drivers shaping the grapevine microbiota at the α- (i.e., within-field) and γ- (i.e., between-field) diversity scales. We demonstrated that vine endospheric microbiota differed according to both the edaphic and plant-specific parameters including cultivar type and age. This work supports the idea of an existing microbial terroir occurring within a domain and offers a new perspective for winemakers to include the microbial terroir in their management practices.
Auteurs, date et publication :
Auteurs Marine Biget , Cendrine Mony , Marc Aubry , Olivier Jambon , Achim Quaiser , Véronique Chable , Sabrina Pernet , Philippe Vandenkoornhuyse
Publication : OENO One
Date : 2021
Volume : 55
Issue : 3
Pages : 299-315
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
According to animal signalling theory, social costs incurred by aggressive conspecifics are one mechanism maintaining signal honesty. Although our understanding of signal evolution has much improved for pigment-based colours, the mechanisms maintaining the honesty of structural colour signals, such as ultraviolet (UV), remain elusive. Here, we used the common lizard (Zootoca vivipara) to test whether the honesty of UV-reflecting signals displayed on male throats is under social control. To do so, we staged agonistic interactions between non-manipulated focal males and opponents of either larger or smaller body size. We manipulated the UV component of the male throat colour patch to create small cheaters with UV-enhanced throats, large cheaters with UV-reduced throats, and their respective controls. In support of a conventional signal hypothesis, focal males were aggressive towards large cheaters and became submissive when these large cheaters retaliated, and were less submissive against small cheaters. However, that focal males were not more aggressive towards small cheaters contradicts our initial predictions. We confirm that male UV reflectance and bite force were good predictors of contest outcomes in control conditions. Overall, we provide partial evidence suggesting that social costs enforce UV signal honesty in common lizards.
Auteurs, date et publication :
Auteurs Anna Kawamoto , Jean-Francois Le Galliard , Arnaud Badiane
Publication : BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY
Date : 2021
Volume : 133
Issue : 4
Pages : 1126-1138
Catégorie(s)
#ANR-Citation #CEREEP #CNRS #ENSRésumé
Tropical forests are biodiversity hotspots, but it is not well understood how this diversity is structured and maintained. One hypothesis rests on the generation of a range of metabolic niches, with varied composition, supporting a high species diversity. Characterizing soil metabolomes can reveal fine-scale differences in composition and potentially help explain variation across these habitats. In particular, little is known about canopy soils, which are unique habitats that are likely to be sources of additional biodiversity and biogeochemical cycling in tropical forests. We studied the effects of diverse tree species and epiphytes on soil metabolomic profiles of forest floor and canopy suspended soils in a French Guianese rainforest. We found that the metabolomic profiles of canopy suspended soils were distinct from those of forest floor soils, differing between epiphyte-associated and non-epiphyte suspended soils, and the metabolomic profiles of suspended soils varied with host tree species, regardless of association with epiphyte. Thus, tree species is a key driver of rainforest suspended soil metabolomics. We found greater abundance of metabolites in suspended soils, particularly in groups associated with plants, such as phenolic compounds, and with metabolic pathways related to amino acids, nucleotides, and energy metabolism, due to the greater relative proportion of tree and epiphyte organic material derived from litter and root exudates, indicating a strong legacy of parent biological material. Our study provides evidence for the role of tree and epiphyte species in canopy soil metabolomic composition and in maintaining the high levels of soil metabolome diversity in this tropical rainforest. It is likely that a wide array of canopy microsite-level environmental conditions, which reflect interactions between trees and epiphytes, increase the microscale diversity in suspended soil metabolomes.
Auteurs, date et publication :
Auteurs Albert Gargallo-Garriga , Jordi Sardans , Abdulwahed Fahad Alrefaei , Karel Klem , Lucia Fuchslueger , Irene Ramírez-Rojas , Julian Donald , Celine Leroy , Leandro Van Langenhove , Erik Verbruggen , Ivan A. Janssens , Otmar Urban , Josep Peñuelas
Publication : Metabolites
Date : 2021
Volume : 11
Issue : 11
Pages : 718
Catégorie(s)
#CNRS #FORET NouraguesRésumé
This contribution focuses on scientific mediation implemented within scientific tourism initiatives in mountain areas. Three case studies in the French Alps support this research: the Jardin Alpin du Lautaret of the University of Grenoble Alpes, the CREA Mont-Blanc, a private research center organizing participatory science and student travel abroad programs and the scientific hut to hut trekking routes in the Écrins National Park, organized jointly with a scientific research project (Labex ITEM, Reflab). Scientific tourism and mediation are first defined. Next, a quantitative and qualitative approach (with interviews and participant observations) allows us to understand the impact and role of scientific mediation within tourism. Results show a high level of interest of the issue within involved publics and a close connection between experience and knowledge. It appears that it is also a tool for public awareness of the challenges of our modern societies.
Auteurs, date et publication :
Auteurs Yannick Vialette , Pascal Mao , Fabien Bourlon
Publication : Journal of Alpine Research | Revue de géographie alpine
Date : 2021
Issue : 109-2
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Abstract. Continental atmospheric relative humidity is a major climate parameter whose variability is poorly understood by global climate models. Models' improvement relies on model–data comparisons for past periods. However, there are no truly quantitative indicators of relative humidity for the pre-instrumental period. Previous studies highlighted a quantitative relationship between the triple oxygen isotope composition of phytoliths, particularly the 17O excess of phytoliths, and atmospheric relative humidity. Here, as part of a series of calibrations, we examine the respective controls of soil water isotope composition, temperature, CO2 concentration and relative humidity on phytolith 17O excess. For that purpose, the grass species Festuca arundinacea was grown in growth chambers where these parameters were varying. The setup was designed to control the evolution of the triple oxygen isotope composition of phytoliths and all the water compartments of the soil–plant–atmosphere continuum. Different analytical techniques (cavity ring-down spectroscopy and isotope ratio mass spectrometry) were used to analyze water and silica. An inter-laboratory comparison allowed to strengthen the isotope data matching. Water and phytolith isotope compositions were compared to previous datasets obtained from growth chamber and natural tropical sites. The results show that the δ′18O value of the source water governs the starting point from which the triple oxygen isotope composition of leaf water, phytolith-forming water and phytoliths evolves. However, since the 17O excess varies little in the growth chamber and natural source waters, this has no impact on the strong relative humidity dependency of the 17O excess of phytoliths, demonstrated for the 40 %–80% relative humidity range. This relative humidity dependency is not impacted by changes in air temperature or CO2 concentration either. A relative humidity proxy equation is proposed. Each per meg of change in phytolith 17O excess reflects a change in atmospheric relative humidity of ca. 0.2 %. The ±15 per meg reproducibility on the measurement of phytolith 17O excess corresponds to a ±3.6 % precision on the reconstructed relative humidity. The low sensitivity of phytolith 17O excess to climate parameters other than relative humidity makes it particularly suitable for quantitative reconstructions of continental relative humidity changes in the past.
Auteurs, date et publication :
Auteurs Clément Outrequin , Anne Alexandre , Christine Vallet-Coulomb , Clément Piel , Sébastien Devidal , Amaelle Landais , Martine Couapel , Jean-Charles Mazur , Christophe Peugeot , Monique Pierre , Frédéric Prié , Jacques Roy , Corinne Sonzogni , Claudia Voigt
Publication : Climate of the Past
Date : 2021
Volume : 17
Issue : 5
Pages : 1881-1902
Catégorie(s)
#ANR-Citation #CNRS #Ecotron de MontpellierRésumé
Increasing temperature and drought can result in leaf dehydration and defoliation even in drought-adapted tree species such as the Mediterranean evergreen Quercus ilex L. The stomatal regulation of leaf water potential plays a central role in avoiding this phenomenon and is constrained by a suite of leaf traits including hydraulic conductance and vulnerability, hydraulic capacitance, minimum conductance to water vapour, osmotic potential and cell wall elasticity. We investigated whether the plasticity in these traits may improve leaf tolerance to drought in two long-term rainfall exclusion experiments in Mediterranean forests. Osmotic adjustment was observed to lower the water potential at turgor loss in the rainfall-exclusion treatments, thus suggesting a stomatal closure at more negative water potentials and a more anisohydric behaviour in drier conditions. Conversely, leaf hydraulic conductance and vulnerability did not exhibit any plasticity between treatments so the hydraulic safety margins were narrower in the rainfall-exclusion treatments. The sequence of leaf responses to seasonal drought and dehydration was conserved among treatments and sites but trees were more likely to suffer losses of turgor and hydraulic functioning in the rainfall-exclusion treatments. We conclude that leaf plasticity might help the trees to tolerate moderate drought but not to resist severe water stress.
Auteurs, date et publication :
Auteurs Jean-Marc Limousin , Amélie Roussel , Jesús Rodríguez-Calcerrada , José M. Torres-Ruiz , Myriam Moreno , Laura Garcia de Jalon , Jean-Marc Ourcival , Guillaume Simioni , Hervé Cochard , Nicolas Martin-StPaul
Publication : Plant, Cell & Environment
Date : 2025
Volume : 45
Issue : 7
Pages : 1967-1984
Catégorie(s)
#CNRS #FORET PuechabonRésumé
The outstanding diversity of Amazonian forests is predicted to be the result of several processes. While tree lineages have dispersed repeatedly across the Amazon, interactions between plants and insects may be the principal mechanism structuring the communities at local scales. Using metabolomic and phylogenetic approaches, we investigated the patterns of historical assembly of plant communities across the Amazon based on the Neotropical genus of trees Inga (Leguminosae) at four, widely separated sites. Our results show a low degree of phylogenetic structure and a mixing of chemotypes across the whole Amazon basin, suggesting that although biogeography may play a role, the metacommunity for any local community in the Amazon is the entire basin. Yet, local communities are assembled by ecological processes, with the suite of Inga at a given site more divergent in chemical defences than expected by chance Synthesis. To our knowledge, this is the first study to present metabolomic data for nearly 100 species in a diverse Neotropical plant clade across the whole Amazonia. Our results demonstrate a role for plant–herbivore interactions in shaping the clade's community assembly at a local scale, and suggest that the high alpha diversity in Amazonian tree communities must be due in part to the interactions of diverse tree lineages with their natural enemies providing a high number of niche dimensions.
Auteurs, date et publication :
Auteurs María-José Endara , Abrianna J. Soule , Dale L. Forrister , Kyle G. Dexter , R. Toby Pennington , James A. Nicholls , Oriane Loiseau , Thomas A. Kursar , Phyllis D. Coley
Publication : Journal of Ecology
Date : 2025
Volume : 110
Issue : 1
Pages : 34-45
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Relationships between tree size and water use indicate how soil water is partitioned between differently sized individuals, and hence competition for water. These relationships are rarely examined, let alone whether there is consistency in shape across populations. Competition for water among plants is often assumed to be size-symmetric, i.e., exponents (b1) of power functions (water use ∝ biomassb1) equal to 1, with all sizes using the same amount of water proportionally to their size. We tested the hypothesis that b1 actually varies greatly, and based on allometric theory, that b1 is only centered around 1 when size is quantified as basal area or sapwood area (not diameter). We also examined whether b1 varies spatially and temporally in relation to stand structure (height and density) and climate. Tree water use ∝ sizeb1 power functions were fitted for 80 species and 103 sites using the global SAPFLUXNET database. The b1 were centered around 1 when tree size was given as basal area or sapwood area, but not as diameter. The 95% confidence intervals of b1 included the theoretical predictions for the scaling of plant vascular networks. b1 changed through time within a given stand for the species with the longest time series, such that larger trees gained an advantage during warmer and wetter conditions. Spatial comparisons across the entire dataset showed that b1 correlated only weakly (R2 < 12%) with stand structure or climate, suggesting that inter-specific variability in b1 and hence the symmetry of competition for water may be largely related to inter-specific differences in tree architecture or physiology rather than to climate or stand structure. In conclusion, size-symmetric competition for water (b1 ≈ 1) may only be assumed when size is quantified as basal area or sapwood area, and when describing a general pattern across forest types and species. There is substantial deviation in b1 between individual stands and species.
Auteurs, date et publication :
Auteurs David I Forrester , Jean-Marc Limousin , Sebastian Pfautsch
Publication : Tree Physiology
Date : 2025
Volume : 42
Issue : 10
Pages : 1916-1927