Résumé
Anthropogenic change in the abundance or identity of dominant top predators may induce reorganizations in whole food webs. Predicting these reorganizations requires identifying the biological rules that govern trophic niches. However, we still lack a detailed understanding of the respective contributions of body size, behaviour (e.g. match between predator hunting mode and prey antipredator strategy), phylogeny and/or ontogeny in determining both the presence and strength of trophic interactions. Here, we address this question by measuring zooplankton numerical response to fish predators in lake enclosures. We compared the fit to zooplankton count data of models grouping zooplankters based either on 1) body sizes, 2) antipredator behaviour, 3) body size combined with antipredator behaviour, or on 4) phylogeny combined with ontogeny (i.e. different life stages of copepods). Body size was a better predictor of zooplankton numerical response to fish than antipredator behaviour, but combining body size and behaviour provided even better predictions. Models based on phylogeny combined with ontogeny clearly outperformed those based on other zooplankton grouping rules, except when phylogeny was poorly resolved. Removing ontogenetic information plagued the predictive power of the highly-resolved (genus-level) phylogenetic grouping but not of medium-resolved or poorly-resolved phylogenetic grouping. Our results support the recent use of phylogeny as a superior surrogate for traits controlling trophic niches, and further highlight the added value of combining phylogeny with ontogenetic traits. Further improvements in our mechanistic understanding of how trophic networks are shaped are bound to uncovering the trophic traits captured by phylogeny and ontogeny, but that currently remain hidden to us. This article is protected by copyright. All rights reserved.
Auteurs, date et publication :
Auteurs Florian Vincent , Andrea Bertolo , Gérard Lacroix , Maud Mouchet , Eric Edeline
Publication : Oikos
Date : 2025
Volume : n/a
Issue : n/a
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Stephanie C Bodin , Jean-François Molino , Guillaume Odonne , Laurent Bremond
Publication : Vegetation History and Archaeobotany
Date : 2025
Pages : 1-14
Catégorie(s)
#CNRS #FORET NouraguesRésumé
The leaf economics spectrum (LES) is based on a suite of leaf traits related to plant functioning and ranges from resource-conservative to resource-acquisitive strategies. However, the relationships with root traits, and the associated belowground plant functioning such as N uptake, including nitrate (NO3−) and ammonium (NH4+), is still poorly known. Additionally, environmental variations occurring both in time and in space could uncouple LES from root traits. We explored, in subalpine grasslands, the relationships between leaf and root morphological traits for three dominant perennial grass species, and to what extent they contribute to the whole-plant economics spectrum. We also investigated the link between this spectrum and NO3− and NH4+ uptake rates, as well as the variations of uptake across four grasslands differing by the land-use history at peak biomass and in autumn. Although poorly correlated with leaf traits, root traits contributed to an economic spectrum at the whole plant level. Higher NH4+ and NO3− uptake abilities were associated with the resource-acquisitive strategy. Nonetheless, NH4+ and NO3−-uptake within species varied between land-uses and with sampling time, suggesting that LES and plant traits are good, but still incomplete, descriptors of plant functioning. Although the NH4+:NO3− uptake ratio was different between plant species in our study, they all showed a preference for NH4+, and particularly the most conservative species. Soil environmental variations between grasslands and sampling times may also drive to some extent the NH4+ and NO3− uptake ability of species. Our results support the current efforts to build a more general framework including above- and below-ground processes when studying plant community functioning.
Auteurs, date et publication :
Auteurs Nicolas Legay , Fabrice Grassein , Cindy Arnoldi , Raphael Segura , Philippe Laîné , Sandra Lavorel , Jean-Christophe Clément
Publication : Oikos
Date : 2025
Volume : 129
Issue : 6
Pages : 830-841
Catégorie(s)
#CNRS #Lautaret #UGARésumé
In the processes controlling ecosystem fertility, fungi are increasingly acknowledged as key drivers. However, our understanding of the rules behind fungal community assembly regarding the effect of soil fertility level remains limited. Using soil samples from typical tea plantations spanning c. 2167 km north-east to south-west across China, we investigated the assemblage complexity and assembly processes of 140 fungal communities along a soil fertility gradient. The community dissimilarities of total fungi and fungal functional guilds increased with increasing soil fertility index dissimilarity. The symbiotrophs were more sensitive to variations in soil fertility compared with pathotrophs and saprotrophs. Fungal networks were larger and showed higher connectivity as well as greater potential for inter-module connection in more fertile soils. Environmental factors had a slightly greater influence on fungal community composition than spatial factors. Species abundance fitted the Zipf–Mandelbrot distribution (niche-based mechanisms), which provided evidence for deterministic-based processes. Overall, the soil fungal communities in tea plantations responded in a deterministic manner to soil fertility, with high fertility correlated with complex fungal community assemblages. This study provides new insights that might contribute to predictions of fungal community complexity.
Auteurs, date et publication :
Auteurs Junjie Guo , Ning Ling , Zhaojie Chen , Chao Xue , Ling Li , Lisheng Liu , Limin Gao , Min Wang , Jianyun Ruan , Shiwei Guo , Philippe Vandenkoornhuyse , Qirong Shen
Publication : New Phytologist
Date : 2025
Volume : 226
Issue : 1
Pages : 232-243
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
Dispersal limitation may drive the structure of fungal microbiota of plant roots at small spatial scales. Fungal root microorganisms disperse through the plant rooting systems from hosts to hosts. Due to a pronounced host-preference effect, the composition of endophytic root microbiota may follow plant distribution. A given plant community may hence include a matrix of host-plant species that represent various habitat permeabilities to fungal dispersal in the floristic landscape. We experimentally tested the effect of host-plant isolation on endophytic fungal assemblages (Ascomycota, Basidiomycota, Glomeromycotina) inhabiting Brachypodium pinnatum roots. We calculated host-plant isolation using Euclidean distance (distance-based dispersal limitation) and resistance distance (functional-based dispersal limitation), based on host presences. All fungal groups were more influenced by the resistance distance between B. pinnatum than by the Euclidean distance. Fungal dispersal was hence strongly related to the spatial distribution of the host plants. The fungal groups displayed however different responses (in richness, abundance, and composition) to host isolation. Additionally, fungal assemblages were more strongly controlled by the degree of connectivity between host plants during the prior year than by current connectivity. This discrepancy may be due to changes in plant species coverage in a year and/or to the delay of dispersal response of fungi. This study it the first to demonstrate how small-scale host-plant distributions mediate connectivity in microorganisms. The consequences of plant distributions for the permeability of the floristic landscape to fungi dispersal appear to control fungal assemblages, but with possibly different mechanisms for the different fungal groups.
Auteurs, date et publication :
Auteurs Cendrine Mony , Nathan Vannier , Philomène Brunellière , Marine Biget , Sophie Coudouel , Philippe Vandenkoornhuyse
Publication : Ecology
Date : 2025
Volume : 101
Issue : 4
Pages : e02976
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
Anticipating the genetic and phenotypic changes induced by natural or artificial selection requires reliable estimates of trait evolvabilities (genetic variances and covariances). However, whether or not multivariate quantitative genetics models are able to predict precisely the evolution of traits of interest, especially fitness-related, life history traits, remains an open empirical question. Here, we assessed to what extent the response to bivariate artificial selection on both body size and maturity in the medaka Oryzias latipes, a model fish species, fits the theoretical predictions. Three lines (Large, Small, and Control lines) were differentially selected for body length at 75 days of age, conditional on maturity. As maturity and body size were phenotypically correlated, this selection procedure generated a bi-dimensional selection pattern on two life history traits. After removal of nonheritable trends and noise with a random effect (“animal”) model, the observed selection response did not match the expected bidirectional response. For body size, Large and Control lines responded along selection gradients (larger body size and stasis, respectively), but, surprisingly, the Small did not evolve a smaller body length and remained identical to the Control line throughout the experiment. The magnitude of the empirical response was smaller than the theoretical prediction in both selected directions. For maturity, the response was opposite to the expectation (the Large line evolved late maturity compared to the Control line, while the Small line evolved early maturity, while the opposite pattern was predicted due to the strong positive genetic correlation between both traits). The mismatch between predicted and observed response was substantial and could not be explained by usual sources of uncertainties (including sampling effects, genetic drift, and error in G matrix estimates).
Auteurs, date et publication :
Auteurs Arnaud Le Rouzic , Clémentine Renneville , Alexis Millot , Simon Agostini , David Carmignac , Éric Édeline
Publication : Ecology and Evolution
Date : 2025
Volume : n/a
Issue : n/a
Catégorie(s)
#ANR-Citation #CNRS #ENS #PLANAQUARésumé
Abstract Aim Locally abundant species are usually widespread, and this pattern has been related to properties of the niches and traits of species. However, such explanations fail to account for the potential of traits to determine species niches and often overlook statistical artefacts. Here, we examine how trait distinctiveness determines the abilities of species to exploit either common habitats (niche position) or a range of habitats (niche breadth) and how niche position and breadth, in turn, affect abundance and occupancy. We also examine how statistical artefacts moderate these relationships. Location Sixteen sites in the Neotropics. Time period 1993?2014. Major taxa studied Aquatic invertebrates from tank bromeliads. Methods We measured the environmental niche position and breadth of each species and calculated its trait distinctiveness as the average trait difference from all other species at each site. Then, we used a combination of structural equation models and a meta-analytical approach to test trait?niche relationships and a null model to control for statistical artefacts. Results The trait distinctiveness of each species was unrelated to its niche properties, abundance and occupancy. In contrast, niche position was the main predictor of abundance and occupancy; species that used the most common environmental conditions found across bromeliads were locally abundant and widespread. Contributions of niche breadth to such patterns were attributable to statistical artefacts, indicating that effects of niche breadth might have been overestimated in previous studies. Main conclusions Our study reveals the generality of niche position in explaining one of the most common ecological patterns. The robustness of this result is underscored by the geographical extent of our study and our control of statistical artefacts. We call for a similar examination across other systems, which is an essential task to understand the drivers of commonness across the tree of life.
Auteurs, date et publication :
Auteurs Nicholas A. C. Marino , Régis Céréghino , Benjamin Gilbert , Jana S. Petermann , Diane S. Srivastava , Paula M. de Omena , Fabiola Ospina Bautista , Laura Melissa Guzman , Gustavo Q. Romero , M. Kurtis Trzcinski , Ignacio M. Barberis , Bruno Corbara , Vanderlei J. Debastiani , Olivier Dézerald , Pavel Kratina , Céline Leroy , Arthur Andrew M. MacDonald , Guillermo Montero , Valério D. Pillar , Barbara A. Richardson
Publication : Global Ecology and Biogeography
Date : 2025
Volume : 29
Issue : 2
Pages : 295-308
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Termites are important plant biomass decomposers. Their digestive activity typically relies on prokaryotes and protozoa present in their guts. In some cases, such as in fungus-growing termites, digestion also relies on ectosymbiosis with specific fungal taxa. To date, the mycobiome of termites has yet to be investigated in detail. We evaluated the specificity of whole-termite associated fungal communities in three wood-feeding termite species. We showed that the whole-termite fungal community spectra are stable over diverse environments, regardless of the host species, and differ markedly from the wood in which they nest. The core mycobiome is similar to that found in other ecologically related insects and consists of a narrow spectrum of common filamentous fungi and yeasts, known for their stress tolerance and their ability to decompose plant biomass. The observed patterns suggest that a number of fungal strains may have a symbiotic relationship with termites, and our results set the stage for future investigations into the interactions between fungi, termites, and their other gut microbiota.
Auteurs, date et publication :
Auteurs Tomáš Větrovský , Patrik Soukup , Petr Stiblik , Kateřina Votýpková , Amrita Chakraborty , Iñaki Odriozola Larrañaga , David Sillam-Dussès , Nathan Lo , Thomas Bourguignon , Petr Baldrian , Jan Šobotník , Miroslav Kolařík
Publication : Fungal Ecology
Date : 2025
Volume : 48
Pages : 100991
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Modulations of advective gas fluxes at the soil–atmosphere interface were investigated using an enhanced experimental setup developed to perform tracer gas percolation experiments through unsaturated soil columns under well-controlled conditions associated with long-term and high-resolution monitoring. The setup design includes the effect of watering and evaporation cycles, barometric pressure fluctuations, variations in the injection pressure, and plant metabolism. Although injected at a constant flux at the base of the columns, SF6 surface fluxes varied on a timescale of hours to days. These modulations are controlled by (a) barometric pressure, (b) water content and distribution, and (c) plant metabolism. All three mainly act on the pressure gradient. Surface gas fluxes decrease under drying conditions, which increases gas porosity and the relative gas permeability and lowers the pressure gradient. Respiration of plant roots is shown to be responsible for daytime–nighttime oscillations of the tracer flux. During nighttime, O2 consumption and CO2 production locally lowers the pressure gradient up to the root zone due to the higher solubility of CO2 in pore water, resulting in an increased SF6 flux at the surface. During daytime, enhanced water loss by evapotranspiration associated with photosynthesis dominated the respiration effect and resulted in decreasing surface gas fluxes, as generally shown for drying conditions. Surface gas fluxes are therefore controlled by combined physical, chemical, and biological processes. This has important consequences, notably when discrete flux measurements are integrated in space and/or in time to quantify emissions or when used for detecting, identifying, or monitoring underground gas sources.
Auteurs, date et publication :
Auteurs Clement Alibert , Eric Pili , Pierre Barre , Florent Massol , Simon Chollet
Publication : Vadose Zone Journal
Date : 2025
Volume : 19
Issue : 1
Pages : e20018
Catégorie(s)
#ANR-Citation #CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Jean-Pierre Vacher , Sophie Manzi , Miguel Trefaut Rodrigues , Antoine Fouquet
Publication : Mitochondrial DNA Part B
Date : 2025
Volume : 5
Issue : 3
Pages : 3088-3090