Résumé
Asexual reproduction has often been regarded as an evolutionary dead end, but asexual lineages (most notably those that are apomictic) are present in several angiosperm families and often comprise a large number of taxa, both widespread and endemic. Investigating correlations between genetic, environmental and taxonomic factors and the incidence of apomixis has represented a challenge for many years, with previous analyses frequently omitting one or more of these variables. Here, flow cytometric seed screening, cytological data and ecological variables have been integrated in a phylogenetic framework to create a comprehensive dataset for 229 of Asteraceae from the European Alps. Data were analysed using phylogenetically informed generalized linear mixed models (pMCMCglmm) where elevation, ploidy and phenology were assessed for their potential correlation with asexual reproduction and apomixis type. Although apomixis is not dominant among the species studied, our results confirm that an odd ploidy (e.g. 3x) and, to a lesser extent, an even polyploid level (i.e. 4x) significantly increase its probability, most probably due to chromosome misalignments during meiosis. The distribution of apomictic species does not correlate with elevation, and there is a weak correlation between early flowering initiation and aposporous apomixis. Although current and future changes in climate may severely impact the survival of the flora of the European Alps, asexual reproduction and polyploidization may prove to be, at least temporarily, lifelines for the survival of a species under the novel climatic conditions. Therefore, uncovering how apomicts and polyploids evolve and persist will be essential for understanding the ecology of the European Alps and hence informing future conservation strategies.
Auteurs, date et publication :
Auteurs Luca Pegoraro , Ellen C Baker , David Aeschimann , Manica Balant , Rolland Douzet , Teresa Garnatje , Maïté S Guignard , Ilia J Leitch , Andrew R Leitch , Luis Palazzesi , Jean-Paul Theurillat , Oriane Hidalgo , Jaume Pellicer
Publication : Botanical Journal of the Linnean Society
Date : 2020
Volume : 194
Issue : 4
Pages : 410-422
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Aim Plant–soil interactions can be major driving forces of community responses to environmental changes in terrestrial ecosystems. These interactions can leave signals in aboveground plant functional traits and belowground microbial activities and these signals can manifest in observed covariations. However, we know little about how these plant–soil linkages vary in response to environmental conditions at biogeographic scales for which experiments are impossible. Here, we investigate patterns of direct and indirect linkages between plant functional traits, soil microbial activities and environmental conditions in mountain grasslands along elevational gradients. Location The French Alps. Taxon Vascular plants and soil microbiota. Methods We analysed observational grassland data sampled along 14 elevational gradients across the entire French Alps (between 1500 and 2800 m of elevation). Using Graphical Lasso, we inferred a partial correlation network to tease apart direct and indirect plant–soil linkages without defining the direction of interactions a priori. Results We found tight spatial associations of plant traits with microbial activities, climate driving the former and soil properties the latter. In these plant–soil linkages, the dominance of specific plant traits was more important than their diversity. We then showed that in sites with conservative plant traits and reduced organic matter quality, soil microbes invested strongly in nutrient acquisition. Main conclusions By investigating plant–soil linkages along elevational gradients in the French Alps, we showed that plant functional traits and belowground microbial activity are tightly linked and how they depend on environmental conditions. Overall, we demonstrated how soil functioning can be integrated in studies of ecosystem shifts under environmental change at large spatial scales.
Auteurs, date et publication :
Auteurs Sarah-Sophie Weil , Camille Martinez-Almoyna , Gabin Piton , Julien Renaud , Louise Boulangeat , Arnaud Foulquier , Amélie Saillard , Philippe Choler , Jérôme Poulenard , Orchamp Consortium , Tamara Münkemüller , Wilfried Thuiller
Publication : Journal of Biogeography
Date : 2025
Volume : 48
Issue : 11
Pages : 2755-2770
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Data assimilation of snow observations significantly improves the accuracy of snow cover simulations. However, remotely-sensed snowpack observations made in areas of complex topography are typically subject to large error and biases, creating a challenge for data assimilation. To improve the reliability of ensemble snowpack simulations, this study investigated the appropriate conditions for assimilating MODIS-like synthetic surface reflectances. We used a simulation system that included the Particle Filter data assimilation technique. More than 270 ensemble simulations involving assimilation of synthetic observations were conducted in a twin experiment procedure for three snow seasons. These tests were aimed at establishing the spectral combination of MODIS-like reflectances that convey the more information in the assimilation system, rendering the most reliable snowpack simulation, and determining the maximum observation errors that the assimilation system could tolerate. The assimilation of the first seven MODIS-like bands, covering visible and near-infrared wavelengths, provided the best scores compared with any other band combination, and thus are highly recommended for use when possible. The simulation system tolerated a maximum deviation from ground truth of 5% without loss of performance. However, the assimilation of the first seven bands of true MODIS surface of reflectance fails on improving simulation results in rouged mountain areas.
Auteurs, date et publication :
Auteurs J. Revuelto , B. Cluzet , N. Duran , M. Fructus , M. Lafaysse , E. Cosme , M. Dumont
Publication : Journal of Hydrology
Date : 2025
Volume : 603
Pages : 126966
Catégorie(s)
#CNRS #Lautaret #UGARésumé
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
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
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
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
Subalpine grasslands support biodiversity, agriculture, and tourism but their resilience to extreme climatic events is challenged accelerating their vulnerability to tipping points. Microbial communities, central in ecosystem functioning, are usually considered more resistant and highly resilient to extreme events albeit their functional redundancy and strong selection by local harsh climatic conditions. This study explored the soil microbial responses upon recurrent spring‐summer droughts associated with early snowmelt in subalpine grasslands mesocosms set‐up at the Lautaret Pass (French Alps). Potential soil microbial respiration, nitrification and denitrification activities were monitored over a period of two growing seasons along with quantification of related gene abundances. Impacts of simulated spring‐summer drought and early snowmelt were quantified to assess their resistance and recovery. Results revealed that droughts had a low and short‐term adverse impact on bacterial total respiration supporting their hypothesized high resilience, i.e. resistance and ability to recover. Nitrification and abundances of the corresponding functional guilds showed relatively strong resistance to summer droughts but declined in response to early snowmelt. This resistance of nitrification was paralleled by the recovery of denitrification and abundances of denitrifying communities from all climatic extremes, except from the summer droughts where nitrifiers were collapsed. Denitrification and respective functional groups faced high impact of applied stresses with strong reduction in abundance and activity. Although, consequently lower denitrifiers' competition for nitrate may be positive for plant biomass production, warnings exist when considering the potential nitrate leaching as well as risks of greenhouses gases emission such as N
2
O from these ecosystems.
Auteurs, date et publication :
Auteurs Farhan Hafeez , Jean‐Christophe Clément , Lionel Bernard , Franck Poly , Thomas Pommier
Publication : Oikos
Date : 2025
Volume : 2023
Issue : 7
Pages : e09836
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mountain grasslands contain large stocks of soil organic carbon (SOC), of which a good part is in labile particulate form. This labile SOC may be protected by cold climate that limits microbial activity. Strong climate change in mountain regions threatens to destabilize these SOC stocks. However, so far the climate response of SOC stocks in mountain grasslands remains highly uncertain, under either warming or cooling conditions. To overcome this knowledge gap, we studied the effect of pedoclimatic regime changes on topsoil (0–10 cm) SOC in two complementary experiments: 3 °C of warming or cooling by reciprocal transplanting to an alpine (2450 m a.s.l.) and a subalpine (1950 m a.s.l.) grassland and 1 °C of warming by open-top chambers in the same grasslands. Topsoil SOC stocks were higher at the alpine site than at the subalpine site, and the biogeochemical signature of the soil organic matter (SOM) also differed between the two study sites. SOM was O-enriched, H-depleted, and more thermally stable at the warmer subalpine site. After three years, abrupt warming by transplanting tended to decrease topsoil SOC content. The remaining SOC was characterized by a more thermostable signature. This result suggests the preferential depletion of labile SOC upon experimental topsoil warming. Cooling did not modify overall SOC content but uphill transplanted topsoils showed a more thermolabile biogeochemical signature. In contrast, open-top chamber warming of alpine and subalpine topsoils caused limited changes to SOC stocks and SOM biogeochemical signature, possibly because the induced pedoclimatic change was more limited and more gradual compared to the warming by transplantating which reduced the annual snow cover period by around 60 days and increased cumulative degree days by a factor of ten as compared to the OTC-induced warming. Gradual temperature changes may take longer to become effective than a shock transplant treatment. We conclude that SOC in mountain grassland topsoils can be highly reactive to climate shocks.
Auteurs, date et publication :
Auteurs Khedim Norine , Poulenard Jérôme , Cecillon Lauric , Baudin François , Barre Pierre , Saillard Amélie , Billur Bektaş , Grigulis Karl , Lavorel Sandra , Münkemüller Tamara , Choler Philippe
Publication : Geoderma
Date : 2023
Volume : 429
Pages : 116238
Catégorie(s)
#ANR-Citation #CNRS #Lautaret #UGARésumé
Seed morphological description is traditionally based on adjectives, which originated from the comparison with other shapes, including geometric figures. Nevertheless, descriptions based on this feature are not quantitative and measurements giving the percentage of similarity of seeds with reference figures are not available in the literature. Lateral views of Silene seeds resemble the cardioid and cardioid-derived figures. Dorsal views, nonetheless, resemble ellipses and derivatives, allowing seed shape quantification by comparison with defined geometric figures. In this work, we apply already-described models as well as new models to the morphological analysis of 51 Silene species. Our data revealed the existence of a link between lateral and dorsal models. Lateral models closed in the hilum region (models LM2 and LM4) were associated with those convex models of the dorsal seed views (DM1-DM4, DM10). Lateral models more open around the hilum region adjusted to seeds characterized as dorso canaliculata type better, i.e., to those geometric models with partial concavities in their dorsal views. The relationship between lateral and dorsal models, as well as between the models to their utility in taxonomy, is discussed.
Auteurs, date et publication :
Auteurs José Javier Martín-Gómez , José Luis Rodríguez-Lorenzo , Bohuslav Janoušek , Ana Juan , Emilio Cervantes
Publication : Taxonomy
Date : 2023
Volume : 3
Issue : 1
Pages : 109-132