Résumé
Understanding the mechanisms that drive the change of biotic assemblages over space and time is the main quest of community ecology. Assessing the relative importance of dispersal and environmental species selection in a range of organismic sizes and motilities has been a fruitful strategy. A consensus for whether spatial and environmental distances operate similarly across spatial scales and taxa, however, has yet to emerge. We used censuses of four major groups of organisms (soil bacteria, fungi, ground insects, and trees) at two observation scales (1-m2 sampling point vs. 2,500-m2 plots) in a topographically standardized sampling design replicated in two tropical rainforests with contrasting relationships between spatial distance and nutrient availability. We modeled the decay of assemblage similarity for each taxon set and site to assess the relative contributions of spatial distance and nutrient availability distance. Then, we evaluated the potentially structuring effect of tree composition over all other taxa. The similarity of nutrient content in the litter and topsoil had a stronger and more consistent selective effect than did dispersal limitation, particularly for bacteria, fungi, and trees at the plot level. Ground insects, the only group assessed with the capacity of active dispersal, had the highest species turnover and the flattest nonsignificant distance−decay relationship, suggesting that neither dispersal limitation nor nutrient availability were fundamental drivers of their community assembly at this scale of analysis. Only the fungal communities at one of our study sites were clearly coordinated with tree composition. The spatial distance at the smallest scale was more important than nutrient selection for the bacteria, fungi, and insects. The lower initial similarity and the moderate variation in composition identified by these distance-decay models, however, suggested that the effects of stochastic sampling were important at this smaller spatial scale. Our results highlight the importance of nutrients as one of the main environmental drivers of rainforest communities irrespective of organismic or propagule size and how the overriding effect of the analytical scale influences the interpretation, leading to the perception of greater importance of dispersal limitation and ecological drift over selection associated with environmental niches at decreasing observation scales.
Auteurs, date et publication :
Auteurs Guille Peguero , Miquel Ferrín , Jordi Sardans , Erik Verbruggen , Irene Ramírez-Rojas , Leandro Van Langenhove , Lore T. Verryckt , Jerome Murienne , Amaia Iribar , Lucie Zinger , Oriol Grau , Jerome Orivel , Clément Stahl , Elodie A. Courtois , Dolores Asensio , Albert Gargallo-Garriga , Joan Llusià , Olga Margalef , Romà Ogaya , Andreas Richter
Publication : Ecology
Date : 2025
Volume : 103
Issue : 2
Pages : e03599
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Meryem Mojtahid , Pauline Depuydt , Aurélia Mouret , Fatine Rihani , Sandrine Le Houedec , Sarah Fiorini , Simon Chollet , Florent Massol , Francis Dohou , Helena L. Filipsson , Wim Boer , Gert-Jan Reichart , Sophie Quinchard , Carole La , Christine Barras
Date : 2022
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #PLANAQUARésumé
Epigenetic mechanisms are believed to play key roles in the establishment of cell-specific transcription programs. Accordingly, the modified bases 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) have been observed in DNA of genomic regulatory regions such as enhancers, and oxidation of 5mC into 5hmC by Ten-eleven translocation (TET) proteins correlates with enhancer activation. However, the functional relationship between cytosine modifications and the chromatin architecture of enhancers remains elusive. To gain insights into their function, 5mC and 5hmC levels were perturbed by inhibiting DNA methyltransferases and TETs during differentiation of mouse embryonal carcinoma cells into neural progenitors, and chromatin characteristics of enhancers bound by the pioneer transcription factors FOXA1, MEIS1, and PBX1 were interrogated. In a large fraction of the tested enhancers, inhibition of DNA methylation was associated with a significant increase in monomethylation of H3K4, a characteristic mark of enhancer priming. In addition, at some specific enhancers, 5mC oxidation by TETs facilitated chromatin opening, a process that may stabilize MEIS1 binding to these genomic regions.
Auteurs, date et publication :
Auteurs Elise A. Mahé , Thierry Madigou , Aurélien A. Sérandour , Maud Bizot , Stéphane Avner , Frédéric Chalmel , Gaëlle Palierne , Raphaël Métivier , Gilles Salbert
Publication : Genome Research
Date : 2017
Volume : 27
Issue : 6
Pages : 947-958
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
The poor constraint of forest Above Ground Biomass (AGB) is responsible, in part, for large uncertainties in modelling future climate scenarios. Terrestrial Laser Scanning (TLS) can be used to derive unbiased and nondestructive estimates of tree structure and volume and can, therefore, be used to address key uncertainties in forest AGB estimates. Here we review our experience of TLS sampling strategies from 27 campaigns conducted over the past 5 years, across tropical and temperate forest plots, where data was captured with a RIEGL VZ-400 laser scanner. The focus is on strategies to derive Geometrical Modelling metrics (e.g. tree volume) over forest plots (≥1 ha) which require the accurate co-registration of 10s to 100s of individual point clouds. We recommend a 10 m × 10 m sampling grid as an approach to produce a point cloud with a uniform point distribution, that can resolve higher order branches (down to a few cm in diameter) towards the top of 30+ m canopies and can be captured in a timely fashion i.e. ∼3–6 days per ha. A data acquisition protocol, such as presented here, would facilitate data interoperability and inter-comparison of metrics between instruments/groups, from plot to plot and over time.
Auteurs, date et publication :
Auteurs Phil Wilkes , Alvaro Lau , Mathias Disney , Kim Calders , Andrew Burt , Jose Gonzalez de Tanago , Harm Bartholomeus , Benjamin Brede , Martin Herold
Publication : Remote Sensing of Environment
Date : 2025
Volume : 196
Pages : 140-153
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Locally, plant species richness supports many ecosystem functions. Yet, the mechanisms driving these often-positive biodiversity–ecosystem functioning relationships are not well understood. Spatial resource partitioning across vertical resource gradients is one of the main hypothesized causes for enhanced ecosystem functioning in more biodiverse grasslands. Spatial resource partitioning occurs if species differ in where they acquire resources and can happen both above- and belowground. However, studies investigating spatial resource partitioning in grasslands provide inconsistent evidence. We present the results of a meta-analysis of 21 datasets from experimental species-richness gradients in grasslands. We test the hypothesis that increasing spatial resource partitioning along vertical resource gradients enhances ecosystem functioning in diverse grassland plant communities above- and belowground. To test this hypothesis, we asked three questions: 1. Does species richness enhance biomass production or community resource uptake across sites? 2. Is there evidence of spatial resource partitioning as indicated by resource tracer uptake and biomass allocation above- and belowground? 3. Is evidence of spatial resource partitioning correlated with increased biomass production or community resource uptake? Although plant species richness enhanced community nitrogen and potassium uptake and biomass production above- and belowground, we found that plant communities did not meet our criteria for spatial resource partitioning, though they did invest in significantly more aboveground biomass in higher canopy layers in mixture relative to monoculture. Furthermore, the extent of spatial resource partitioning across studies was not positively correlated with either biomass production or community resource uptake. Our results suggest that spatial resource partitioning across vertical resource gradients alone does not offer a general explanation for enhanced ecosystem functioning in more diverse temperate grasslands.
Auteurs, date et publication :
Auteurs Kathryn Barry , Jasper Van Ruijven , Liesje Mommer , Yongfei Bai , Carl Beierkuhnlein , Nina Buchmann , Hans De Kroon , Anne Ebeling , Nico Eisenhauer , Claudia Guimaraes-Steinicke , Anke Hildebrandt , Forest Isbell , Alexandru Milcu , Carsten Neßhöver , Peter Reich , Christiane Roscher , Leopold Sauheitl , Michael Scherer-Lorenzen , Bernhard Schmid , David Tilman
Date : 2025
Catégorie(s)
#CNRS #Ecotron de MontpellierAuteurs, date et publication :
Auteurs Antoine Fouquet , QUENTIN Martinez , LAUREN Zeidler , Elodie A Courtois , PHILIPPE Gaucher , Michel Blanc , JUCIVALDO DIAS Lima , SERGIO MARQUES Souza , MIGUEL T Rodrigues , PHILIPPE JR Kok
Publication : Zootaxa
Date : 2025
Volume : 4084
Issue : 1
Pages : 79-104
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Upon advances in sequencing techniques, more and more morphologically identical organisms are identified as cryptic species. Often, mutualistic interactions are proposed as drivers of diversification. Species of the neotropical parabiotic ant association between Crematogaster levior and Camponotus femoratus are known for highly diverse cuticular hydrocarbon (CHC) profiles, which in insects serve as desiccation barrier but also as communication cues. In the present study, we investigated the association of the ants’ CHC profiles with genotypes and morphological traits, and discovered cryptic species pairs in both genera. To assess putative niche differentiation between the cryptic species, we conducted an environmental association study that included various climate variables, canopy cover, and mutualistic plant species. Although mostly sympatric, the two Camponotus species seem to prefer different climate niches. However in the two Crematogaster species, we could not detect any differences in niche preference. The strong differentiation in the CHC profiles may thus suggest a possible role during speciation itself either by inducing assortative mating or by reinforcing sexual selection after the speciation event. We did not detect any further niche differences in the environmental parameters tested. Thus, it remains open how the cryptic species avoid competitive exclusion, with scope for further investigations.
Auteurs, date et publication :
Auteurs Juliane Hartke , Philipp P. Sprenger , Jacqueline Sahm , Helena Winterberg , Jérôme Orivel , Hannes Baur , Till Beuerle , Thomas Schmitt , Barbara Feldmeyer , Florian Menzel
Publication : Ecology and Evolution
Date : 2025
Volume : 9
Issue : 16
Pages : 9160-9176
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouAuteurs, date et publication :
Auteurs Flavia A Esteves , Brian L Fisher
Publication : ZooKeys
Date : 2025
Volume : 1074
Pages : 83
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Brigitte Vinçon-Leite , Yi Hong , Viet Tran Khac , Denis Plec , Chenlu Li , Philippe Dubois , Mohamed Saad , Bruno J Lemaire , Gabriel Hmimina , Kamel Soudani , others
Date : 2025
Catégorie(s)
#⛔ No DOI found #CNRS #ENS #PLANAQUARésumé
Abstract Most genetic alterations that drive melanoma development and resistance to targeted therapy have been uncovered. In contrast, and despite their increasingly recognized contribution, little is known about the non-genetic mechanisms that drive these processes. Here, we performed in vivo gain-of-function CRISPR screens and identified SMAD3, BIRC3, and SLC9A5 as key actors of BRAFi resistance. We show that their expression levels increase during acquisition of BRAFi resistance and remain high in persister cells and during relapse. The upregulation of the SMAD3 transcriptional activity (SMAD3-signature) promotes a mesenchymal-like phenotype and BRAFi resistance by acting as an upstream transcriptional regulator of potent BRAFi-resistance genes such as EGFR and AXL. This SMAD3-signature predicts resistance to both current melanoma therapies in different cohorts. Critically, chemical inhibition of SMAD3 may constitute amenable target for melanoma since it efficiently abrogates persister cells survival. Interestingly, decrease of SMAD3 activity can also be reached by inhibiting the Aryl hydrocarbon Receptor (AhR), another druggable transcription factor governing SMAD3 expression level. Our work highlights novel drug vulnerabilities that can be exploited to develop long-lasting antimelanoma therapies.
Auteurs, date et publication :
Auteurs Arthur Gautron
Publication : EMBO Molecular Medicine
Date : 2021
Volume : 13
Issue : 5
Pages : e13466