Résumé
Gut microbiome diversity and functions are jointly shaped by the host’s genetic background and environmental conditions, but the consequences of this interaction are still unclear. Unravelling the effect of the interaction between evolution and environment on the gut microbiome is particularly relevant considering the unprecedented level of human-driven disruption on the ecological and evolutionary trajectories of species. Here, we aimed to evaluate whether size-selective mortality influences the gut microbiome of medaka (Oryzias latipes), how environment conditions modulate the effect of the genetic background of medaka on their microbiota, and the association between microbiome diversity and medaka fitness. To do so, we studied two lineages of medaka that were raised under antagonistic size-selective regimes for 10 generations (i.e. the largest or the smallest breeders were removed to mimic fishing-like or natural mortality). In pond mesocosms, the two lineages were subjected to contrasting population density and light intensity (i.e. used as a proxy of primary production, hence resource availability). We observed significant differences in the gut microbiome composition and richness between the two lines, and this effect was mediated by light intensity. Indeed, the bacterial richness of fishing-like medaka (small-breeder line) was reduced by 34% under low-light conditions compared to high-light conditions, while it remained unchanged in natural mortality-selected medaka (large-breeder line). However, the observed changes in bacterial richness did not correlate with changes in growth rate or body condition, possibly due to functional redundancy among the microbial taxa residing in the gut. Given the growing evidence about the gut microbiomes importance to host health, more in-depth studies are required to fully understand the role of the microbiome in size-selected organisms and the possible ecosystem-level consequences.
Auteurs, date et publication :
Auteurs C. Evangelista , S. Kamenova , B. Diaz Pauli , J. Sandkjenn , L. A. Vøllestad , E. Edeline , P. Trosvik , EJ de Muinck
Date : 2023
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Partitioning soil organic carbon (SOC) in fractions with different biogeochemical stability is useful to better understand and predict SOC dynamics and provide information related to soil health. Multiple SOC partition schemes exist, but few of them can be implemented on large sample sets and therefore be considered relevant options for soil monitoring. The well-established particulate organic carbon (POC) vs. mineral-associated organic carbon (MAOC) physical fractionation scheme is one of them. Introduced more recently, Rock-Eval® thermal analysis coupled with the PARTYSOC machine learning model can also fractionate SOC into active (Ca) and stable SOC (Cs). A debate is emerging as to which of these methods should be recommended for soil monitoring. To investigate the complementarity or redundancy of these two fractionation schemes, we compared the quantity and environmental drivers of SOC fractions obtained on an unprecedented dataset from mainland France. About 2000 topsoil samples were recovered all over the country, presenting contrasting land cover and pedoclimatic characteristics, and analysed. We found that the environmental drivers of the fractions were clearly different, the more stable MAOC and Cs fractions being mainly driven by soil characteristics, whereas land cover and climate had a greater influence on more labile POC and Ca fractions. The stable and labile SOC fractions provided by the two methods strongly differed in quantity (MAOC/Cs=1.88 ± 0.46 and POC/Ca=0.36 ± 0.17; n=843) and drivers, suggesting that they correspond to fractions with different biogeochemical stability. We argue that, at this stage, both methods can be seen as complementary and potentially relevant for soil monitoring. As future developments, we recommend comparing how they relate to indicators of soil health such as nutrient availability or soil structural stability and how their measurements can improve the accuracy of SOC dynamics models.
Auteurs, date et publication :
Auteurs Amicie A. Delahaie , Lauric Cécillon , Marija Stojanova , Samuel Abiven , Pierre Arbelet , Dominique Arrouays , François Baudin , Antonio Bispo , Line Boulonne , Claire Chenu , Jussi Heinonsalo , Claudy Jolivet , Kristiina Karhu , Manuel Martin , Lorenza Pacini , Christopher Poeplau , Céline Ratié , Pierre Roudier , Nicolas P. A. Saby , Florence Savignac
Publication : SOIL
Date : 2024
Volume : 10
Issue : 2
Pages : 795-812
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Jaimie T.A. Dick , Ciaran Laverty , Jack J. Lennon , Daniel Barrios-O'Neill , Paul J. Mensink , J. Robert Britton , Vincent Médoc , Pieter Boets , Mhairi E. Alexander , Nigel G. Taylor , Alison M. Dunn , Melanie J. Hatcher , Paula J. Rosewarne , Steven Crookes , Hugh J. MacIsaac , Meng Xu , Anthony Ricciardi , Ryan J. Wasserman , Bruce R. Ellender , Olaf L.F. Weyl
Publication : Journal of Applied Ecology
Date : 2025
Volume : 54
Issue : 4
Pages : 1259-1267
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
In many grasslands, species with specific traits occupy unique temporal positions within communities. Such intra-annual segregation is predicted to be greatest in systems with high intra-annual climate variability because fluctuating environmental conditions provide opportunities for temporal niche partitioning among species. However, because most studies on intra-annual community dynamics have been conducted at individual sites, relationships between intra-annual climate variability and seasonal community dynamics at global scales have not yet been identified. Furthermore, the same characteristics that promote species-specific responses to fluctuations in environmental conditions may also drive species-specific responses to global change drivers such as eutrophication. Research provides evidence that eutrophication alters inter-annual plant community dynamics yet understanding of how it alters intra-annual dynamics remains limited.
We used early-season and late-season compositional data collected from 10 grassland sites around the world to ask how intra-annual variability in precipitation and temperature as well as nutrient enrichment shape intra-annual species segregation, or seasonal β-diversity, in plant communities. We also assessed whether changes in the abundances of specific functional groups including annual forbs, perennial forbs, C3 and C4 graminoids, and legumes underpin compositional differences between early- and late-season communities and treatments. We found that intra-annual temperature variability and seasonal β-diversity were positively related but observed no relationship between intra-annual precipitation variability and seasonal β-diversity. This suggests that positive relationships between α-diversity and intra-annual temperature variability identified in earlier studies may be underpinned by the positive influence of intra-annual temperature variability on temporal segregation of species within growing seasons. We found that nutrient enrichment increased seasonal β-diversity via increased turnover of species between early- and late-season communities. This finding mirrors patterns observed at inter-annual scales and suggests fertilization can alter compositional dynamics via similar mechanisms at varied temporal scales. Finally, fertilization reduced the abundance of C4 graminoids and legumes and eliminated intra-annual differences in these groups. In contrast, fertilization resulted in intra-annual differences in C3 graminoids which were not observed in control conditions, and increased abundance of C3 graminoids and annual forbs overall. Our study provides new insight into how intra-annual climate variability and nutrient enrichment influence biodiversity and seasonal dynamics in global grasslands.
Auteurs, date et publication :
Auteurs Magda Garbowski , Elizabeth Boughton , Anne Ebeling , Philip Fay , Yann Hautier , Hanna Holz , Anke Jentsch , Stephanie Jurburg , Emma Ladouceur , Jason Martina , Timothy Ohlert , Xavier Raynaud , Christiane Roscher , Grégory Sonnier , Pedro Maximiliano Tognetti , Laura Yahdjian , Peter Wilfahrt , Stan Harpole
Date : 2023
Catégorie(s)
#CEREEP #CNRS #ENSRésumé
Responses of ecosystems to modifications of their environmental conditions are usually considered in terms of biodiversity or function. Maybe because they represent a hidden part of ecosystems, responses of ecological interactions are rarely studied. A more comprehensive view of the processes underlying the restructuring of food webs under environmental gradients appears crucial to understand how ecosystems functionalities are altered. We address this general issue in an experiment where trophic interactions are reorganized under a gradient of top–down effects (predation pressure) and bottom–up effects (nutrient availability). Unimodal relationships of species diversity are pervasive in ecology; we extend this principle to food-web topology: in our study, most topological descriptor values peak at intermediate predation intensity. The same unimodal pattern holds for network complexity, measured by entropy and scaled entropy (a measure independent of species diversity). Moreover, food web complexity is maximized at higher fish abundance when nutrient availability is increased. We infer that whereas in absence of top predators, a mechanism of competitive exclusion takes place, and indirect facilitation process underlies systems with a moderate predation pressure. These results highlight the importance of the dynamic reorganization of trophic links in response to bottom–up and top–down effects. Interaction between bottom–up and top–down forces argue for multifactorial studies of ecological effects.
Auteurs, date et publication :
Auteurs Benoit Gauzens , Stéphane Legendre , Xavier Lazzaro , Gérard Lacroix
Publication : Oikos
Date : 2016
Volume : 125
Issue : 4
Pages : 595-603
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Kejun Zou , Elisa Thébault , Gérard Lacroix , Sébastien Barot , Shawn Leroux
Publication : Functional Ecology
Date : 2025
Volume : 30
Issue : 8
Pages : 1454-1465
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs LoïC Harrault , Beatrice Allard , Michael Danger , Florence Maunoury-Danger , Alexis Guilpart , Gerard Lacroix
Publication : Freshwater Biology
Date : 2025
Volume : 57
Issue : 11
Pages : 2390-2400
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Loïc Harrault , Béatrice Allard , Jacques Mériguet , David Carmignac , Samuel Perret , Sylvain Huon , Eric Edeline , Gérard Lacroix
Date : 2025
Volume : 15
Catégorie(s)
#⛔ No DOI found #CNRS #ENS #PLANAQUARésumé
In the subsurface, water content, gas solubility, organic mater
degradation as well as plant and microorganism respiration control
gas fluxes between soil and the atmosphere. Indeed, all of this
controls the partial pressures of major gas species, such as O2 and
CO2 , which controls in turn the advective and diffusive transport of
all the gaseous species, including the inert gases. Because these
processes vary in intensity with time and space, it is very
challenging to define where, when and how to measure gas fluxes
between soil and the atmosphere. This is equaly important for
detection of anomalous fluxes as well as for the calculation of
relevant mass budgets. We focus here on inert gases because of their
relevance as tracers for a large variety of processes. An
experimental setup was developed and validated at the ECOTRON
IleDeFrance research center. It is composed of a 60-cm high and 40-cm
diameter sand column placed under controlled conditions (water
content, temperature, pressure, light) in a climatic chamber. Plants
are grown at the top of the column. An inert gas (SF6) is injected at
the bottom and its flux is continuously monitored at the surface. A
similar experimental setup is run without plants. Effects of
watering, daytime/nighttime plant activity, cut out of leaves, plant
destruction as well as of other solicitations are determined and
discussed. First-order models are proposed and their results are
compared to the experimental data. These models are based on
consumption of O2 , production of CO2 with a higher solubility in
water and their effects on inert gas advection-dispersion.
Auteurs, date et publication :
Auteurs Clément Alibert , Eric Pili , Pierre Barré , Florent Massol
Date : 2018
Volume : 20
Pages : 2177
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Climate change that we are facing is expected to influence multiple environmental processes, including weathering and
soil formation. While temperature and partial pressure of CO2 in the atmosphere are expected to directly influence
dissolution, in the soils their effect is compounded by plant response to environmental change. In order to evaluate effect
of temperature and CO on rock dissolution, plant growth and nutrient uptake, we conducted mesocosm experiments
2where we exposed three different plants grown in unweathered basalt tephra, as well as unplanted but not sterilized
control, to following conditions: two different CO2 levels, 400 ppm and 800 ppm, and two climate regimes, with ambient
(21-25°C) and elevated (25-30°C) temperatures. Tight control on the environmental variables was possible by conducting
experiments at the ECOTRON Ile-De-France facility, France. Studied plants included velvet mesquite (Prosopis velutina),
green spangletop (Leptochloa dubia), and alfalfa (Medicago sativa). Both mesquite and alfalfa were inoculated with the
nitrogen-fixing bacteria. Pore water solution and leachates were collected at set intervals and analyzed to determine pH,
conductivity, and concentrations of C, N, and lithogenic elements. At the end of the experiment, all plant biomass was
collected, dried, weighed, and subsamples digested to determine nutrient uptake by the plants. Soils were also analyzed
for changes in organic and inorganic C and total N content. We observed significant increase in solution concentrations for
several lithogenic elements, such as Si, Mg, and P with increase in temperature. Concentrations in the biomass were also
increased for many elements. However, biomass production was smaller at elevated temperature for alfalfa, resulting in
less treatment difference when total uptake by the plants was compared. Fewer effects of elevated CO were measured;
2among them was greater carbonate precipitation in the soil. This study indicates that climate change would affect both abiotic and biotic components of soil formation.
Auteurs, date et publication :
Auteurs K. Dontsova , Sabrina Juarez , E. Villasenor , J.-F. Le Galliard , Simon Chollet , Mathieu Llavata , Florent Massol , E. Hunt , Pierre Barré , D. Daval , A. Gelabert , G. Barron-Gafford , J. van Haren , P. Troch , R. Ferriere
Date : 2025