Résumé
Sanguina nivaloides is the main alga forming red snowfields in high mountains and Polar Regions. It is non-cultivable. Analysis of environmental samples by X-ray tomography, focused-ion-beam scanning-electron-microscopy, physicochemical and physiological characterization reveal adaptive traits accounting for algal capacity to reside in snow. Cysts populate liquid water at the periphery of ice, are photosynthetically active, can survive for months, and are sensitive to freezing. They harbor a wrinkled plasma membrane expanding the interface with environment. Ionomic analysis supports a cell efflux of K+, and assimilation of phosphorus. Glycerolipidomic analysis confirms a phosphate limitation. The chloroplast contains thylakoids oriented in all directions, fixes carbon in a central pyrenoid and produces starch in peripheral protuberances. Analysis of cells kept in the dark shows that starch is a short-term carbon storage. The biogenesis of cytosolic droplets shows that they are loaded with triacylglycerol and carotenoids for long-term carbon storage and protection against oxidative stress.
Auteurs, date et publication :
Auteurs Jade A. Ezzedine , Clarisse Uwizeye , Grégory Si Larbi , Gaelle Villain , Mathilde Louwagie , Marion Schilling , Pascal Hagenmuller , Benoît Gallet , Adeline Stewart , Dimitris Petroutsos , Fabienne Devime , Pascal Salze , Lucie Liger , Juliette Jouhet , Marie Dumont , Stéphane Ravanel , Alberto Amato , Jean-Gabriel Valay , Pierre-Henri Jouneau , Denis Falconet
Publication : Nature Communications
Date : 2023
Volume : 14
Issue : 1
Pages : 7500
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Flowering phenology is important in the adaptation of many plants to their local environment, but its adaptive value has not been extensively studied in herbaceous perennials. We used Arabis alpina as a model system to determine the importance of flowering phenology to fitness of a herbaceous perennial with a wide geographical range. Individual plants representative of local genetic diversity (accessions) were collected across Europe, including in Spain, the Alps and Scandinavia. The flowering behaviour of these accessions was documented in controlled conditions, in common-garden experiments at native sites and in situ in natural populations. Accessions from the Alps and Scandinavia varied in whether they required exposure to cold (vernalization) to induce flowering, and in the timing and duration of flowering. By contrast, all Spanish accessions obligately required vernalization and had a short duration of flowering. Using experimental gardens at native sites, we show that an obligate requirement for vernalization increases survival in Spain. Based on our analyses of genetic diversity and flowering behaviour across Europe, we propose that in the model herbaceous perennial A. alpina, an obligate requirement for vernalization, which is correlated with short duration of flowering, is favoured by selection in Spain where the plants experience a long growing season.
Auteurs, date et publication :
Auteurs Jörg Wunder , Andrea Fulgione , Per Toräng , Stefan Wötzel , Michel Herzog , José Ramón Obeso , Yiannis Kourmpetis , Roeland van Ham , Thomas Odong , Marco Bink , Ulla Kemi , Jon Ågren , George Coupland
Publication : Proceedings of the Royal Society B: Biological Sciences
Date : 2023
Volume : 290
Issue : 2011
Pages : 20231401
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The re-assembly of plant communities during climate warming depends on several concurrent processes. Here, we present a novel framework that integrates spatially explicit sampling, plant trait information and a warming experiment to quantify shifts in these assembly processes. By accounting for spatial distance between individuals, our framework allows separation of potential signals of environmental filtering from those of different types of competition. When applied to an elevational transplant experiment in the French Alps, we found common signals of environmental filtering and competition in all communities. Signals of environmental filtering were generally stronger in alpine than in subalpine control communities, and warming reduced this filter. Competition signals depended on treatments and traits: Symmetrical competition was dominant in control and warmed alpine communities, while hierarchical competition was present in subalpine communities. Our study highlights how distance-dependent frameworks can contribute to a better understanding of transient re-assembly dynamics during environmental change.
Auteurs, date et publication :
Auteurs Billur Bektaş , Wilfried Thuiller , Julien Renaud , Maya Guéguen , Irene Calderón-Sanou , Jean-Gabriel Valay , Marie-Pascale Colace , Tamara Münkemüller
Publication : Ecology Letters
Date : 2025
Volume : 26
Issue : 7
Pages : 1119-1131
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Only a few studies have examined responses of grassland functional diversity to management and major environmental gradients, in order to address the question of whether grassland use can promote functional divergence. For five grassland sites in Israel, Portugal, the Czech Republic, Mediterranean France, and the French Alps, where traditional grassland management is being abandoned, we quantified community-weighted means (CWM) and functional divergence (FDvg) for the three Leaf–Height–Seed (LHS) traits, individually and in combination. Responses of CWM and FDvg to land use were analyzed by mixed linear models with aridity, phosphorus, fertility, and the fractions of grasses and annuals as covariates.
Auteurs, date et publication :
Auteurs Sandra Lavorel , Francesco de Bello , Karl Grigulis , Jan Lepš , Eric Garnier , Helena Castro , Jiri Dolezal , Carly Godolets , Fabien Quétier , Aurélie Thébault
Publication : Israel Journal of Ecology & Evolution
Date : 2025
Volume : 57
Issue : 1-2
Pages : 53-72
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Karl Grigulis , Sandra Lavorel , Ute Krainer , Nicolas Legay , Catherine Baxendale , Maxime Dumont , Eva Kastl , Cindy Arnoldi , Richard D. Bardgett , Franck Poly , Thomas Pommier , Michael Schloter , Ulrike Tappeiner , Michael Bahn , Jean-Christophe Clément , Michael Hutchings
Publication : Journal of Ecology
Date : 2025
Volume : 101
Issue : 1
Pages : 47-57
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Backgrounds and Aims Leaf functional traits have been used as a basis to categoize plants across a range of resource-use specialization, from those that conserv
Auteurs, date et publication :
Auteurs Fabrice Grassein , Servane Lemauviel-Lavenant , Sandra Lavorel , Michael Bahn , Richard D. Bardgett , Marie Desclos-Theveniau , Philippe Laîné
Publication : Annals of Botany
Date : 2015
Volume : 115
Issue : 1
Pages : 107-115
Catégorie(s)
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Auteurs Florian C. Boucher , Wilfried Thuiller , Cristina Roquet , Rolland Douzet , Serge Aubert , Nadir Alvarez , Sébastien Lavergne
Publication : Evolution
Date : 2025
Volume : 66
Issue : 4
Pages : 1255-1268
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Francesco de Bello , Sandra Lavorel , Cécile H. Albert , Wilfried Thuiller , Karl Grigulis , Jiři Dolezal , Štepán Janeček , Jan Lepš
Publication : Methods in Ecology and Evolution
Date : 2025
Volume : 2
Issue : 2
Pages : 163-174
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mapping snow conditions in alpine areas is crucial for monitoring local hydrology to support water resource management decisions. Recently, the use of structure‐from‐motion multiview stereo 3‐D reconstruction (or SFM photogrammetry) to derive high‐resolution digital elevation models (DEMs) has become popular for mapping snow depth in alpine areas. In this study, methods for communicating spatial uncertainties in snow depth calculated from SFM‐derived DEMs are presented using a case study in the French Alps. A spatially varying snow depth precision estimate was determined using an error propagation model based on the precision of the acquired SFM DEMs, which was obtained from repeated unmanned aerial vehicle flights. Spatially varying snow depth detection limits were determined using Student's t distribution. It was found that snow depths as shallow as 1 to 5 cm could be detected with high confidence for most of the study area. Areas of high uncertainties were generally related to where the extent of the ground control coverage did not match in the snow‐on and snow‐off surveys and in areas with higher surface roughness. A map of the snow depth detection threshold was found to be useful for identifying areas with high uncertainties and potential biases in the SFM snow depths, such as errors due to changes in topography between DEM acquisition dates and poor SFM reconstruction.
Auteurs, date et publication :
Auteurs Jason Goetz , Alexander Brenning
Publication : Water Resources Research
Date : 2025
Volume : 55
Issue : 9
Pages : 7772-7783
Catégorie(s)
#CNRS #Lautaret #UGARésumé
In the Caryophyllaceae, seed surfaces contain cell protrusions, of varying sizes and shapes, called tubercles. Tubercles have long been described in many species, but quantitative analyses with measurements of size and shape are lacking in the literature. Based on optical photography, the seeds of Silene were classified into four types: smooth, rugose, echinate and papillose. Seeds in each of these groups have characteristic geometrical properties: smooth seeds lack tubercles and have the highest values of circularity and solidity in their lateral views, while papillose seeds have the largest tubercles and lowest values of circularity and solidity both in lateral and dorsal views. Here, tubercle width, height and slope, maximum and mean curvature values and maximum to mean curvature ratio were obtained for representative seeds of a total of 31 species, 12 belonging to Silene subg. Behenantha and 19 to S. subg. Silene. The seeds of the rugose type had lower values of curvature. Additionally, lower values of curvature were found in species of S. subg. Silene in comparison with S. subg. Behenantha. The seeds of S. subg. Behenantha had higher values of tubercle height and slope and higher values of maximum and average curvature and maximum to mean curvature ratio.
Auteurs, date et publication :
Auteurs José Luis Rodríguez-Lorenzo , José Javier Martín-Gómez , Ana Juan , Ángel Tocino , Emilio Cervantes
Publication : Plants
Date : 2023
Volume : 12
Issue : 19
Pages : 3444