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Strain pattern and active faults' compatibility across the Western Alps revealed by 25 years of GNSS measurements
No full textUpdated GNSS solutions integrating 25 years of GNSS data allow to evaluate deformation rates of 0.1–1 mm/yr in the WesternAlps, and in particular to compare the High Durance fault (HDF) activity (internal zones) with the Belledonne Fault (BDF)(external zone). Strain rate estimates are larger across HDF (19 ± 3 nanostrain/yr EW extension) than BDF (5 ± 1 nanostrain/yr EW compression). Fault slip rates indicate dominant dextral strike-slip motion on BDF (0.2 ± 0.1 mm/yr), whileHDF exhibits major extensional motion (0.3 ± 0.1 mm/yr). These two faults represent therefore the broader kinematics of theW-Alps characterized by seismicity showing mainly extensional deformation in the internal zones (HDF) and strike-slip motionin the external zone (BDF). Finally, a rigid 3-blocks model explains 29% of the observed GNSS velocity field and confirms theHDF and BDF deformation styles and their interconnected roles in the W-Alpine deformation framework
Refining near-infrared spectroscopy for collagen quantification: A new predictive model for archaeological bone
No full textInternational audienceCollagen is a vital archaeological material, preserving biochemical signatures that provide insights into past environments, diets, and human-animal interactions. However, diagenesis can lead to rapid and inconspicuous collagen degradation. Given the variability in collagen preservation and its significance for analyses such as radiocarbon dating, stable isotope analysis, and ZooMS, researchers have developed prescreening techniques to assess collagen preservation before destructive sampling. Current prescreening approaches, including %N and C:N ratios, typically require sample destruction and access to equipped laboratories. Spectroscopic techniques such as Raman spectroscopy and Fourier Transform Infrared spectroscopy have been explored as alternatives, but they are limited in penetration depth, generalizability (at present at least), and are often still destructive, if minimally.Here, we further develop single-point near-infrared (NIR) spectroscopy as a fully non-destructive, rapid, and field-portable method for prescreening bone for collagen preservation. Unlike FTIR and Raman spectroscopic techniques, NIR light penetrates below the surface of bone, enabling assessment of internal collagen preservation without destructive sample preparation. Using Partial Least Squares Regression (PLSR) and Random Forest (RF) modeling, we trained predictive models on whole bones with known collagen yields and validated the models on an independent archaeological collection. Both PLSR and RF models, when restricted to the 2030–2060 nm range, demonstrate strong and comparable performance while avoiding wavelengths associated with consolidants in our reference library. The models outperform traditional % N-based methods in identifying suitable samples for radiocarbon dating. These models enable the high-throughput screening of large collections of bone, improving sample selection and minimizing unnecessary destructive analysis
Sediment routing and palaeogeographic evolution of the Western Alpine Foreland Basin during the early collisional stage
No full textInternational audienceIn the Western Alpine Foreland Basin (WAFB), Late Eocene and Miocene periods were characterized by longitudinal sediment routing systems: The first one was situated within the turbidite basin during the underfilled phase and exhibited a northward orientation toward the Swiss Basin, whereas the second was located in the Rhône Valley during the overfilled phase and was directed southward toward the Mediterranean Sea. The transition between these two periods occurred during the Oligocene, which corresponds to both the underfilled/ overfilled transition and the early overfilled period. In this study, we provide new fieldwork observations, seismic and well data interpretations, biostratigraphic analyses and a literature synthesis to reconstruct the palaeogeographic and source-to-sink evolution of the WAFB from Priabonian to Aquitanian. The aim is to discuss this reorganisation of sediment routing in relation to the evolution of the Alpine orogenic wedge, as well as the structural inheritance and the suite of geodynamic events that affected southeastern France during the mid-Cenozoic. We divided the WAFB sedimentary formations into four depositional sequences (S1 to S4). During the deposition of the first two sequences (Priabonian to early late Rupelian; ~37.4-28.8 Ma), the WAFB routing system was influenced by the end of the Pyrenean-Provençal orogeny, the European Cenozoic Rifting System (controlling the Rhône Valley s.l.) and the Alpine orogenic wedge (controlling the Alpine foredeep). The very first connection between the Alpine domain and the Rhône Valley is established at ~30 Ma, during the late Rupelian (S2 highstand), controlled by E-W inherited Pyrenean-Provençal structures implying a 'broken foreland'. In the meanwhile, from the Dévoluy Basin and northward, the orogenic wedge controlled a classical, although thin, foreland basin characterized by a northward sediment routing connected to the Northern Alpine Foreland Basin. Most of the S3 sequence (Latest Rupelian to middle Chattian; ~28.8-23.25 Ma) corresponds to a decrease of clastic Alpine inputs throughout SE France caused by a reorganisation of the drainage network related with the exhumation of the southern External Crystalline Massifs. S3 highstand and S4 sequence (late Chattian to Aquitanian; from ~23.25 Ma) correspond to the establishment of a longitudinal sediment routing system in the Rhône Valley, with material flowing southwards toward the Gulf of Lion, and supplied by the Palaeo-Isère to the north and potentially by the Palaeo-Durance to the south. This final stage in the reorganisation of the drainage network is clearly associated with the post-rift phase of the Gulf of Lion, which facilitated the opening of a new sink and the ultimate southward migration of the sedimentary area
The black-chinned tilapia Sarotherodon melanotheron, a model for environmental genomics and aquaculture resilience in the Western African's context of climate change
No full textInternational audienceThe euryhaline black-chinned tilapia (Sarotherodon melanotheron, Rüppell, 1852) has long been recognised as a valuable local resource in West African aquaculture and artisanal fisheries. Its production contributes to food security, the local economy and farmer’s incomes. Initial research on this species focused on understanding its biology and ecology in the field and in controlled conditions, and then on evaluating and improving practices to increase local production. More recently, the scope of this research has expanded to include investigations integrating molecular approaches in wild populations, such as population genetics and genomics studies, as well as ecophysiological and functional transcriptomics. Additionally, issues related to climate change have been incorporated. In the range of the black-chinned tilapia, the increase in salinity observed in so-called ‘inverse estuaries’ in Senegal, where hypersaline conditions of up to 130 psu may prevail throughout the year, has attracted significant attention. Even for a euryhaline species such as S. melanotheron, such conditions impose substantial energetic costs, resulting in observed phenotypic and adaptive changes to the fish’s biological and life-history traits. Salinity is a major issue in tilapia aquaculture. Improved production could be achieved by selecting strains from populations that are tolerant to salinity, or by hybridising with less tolerant tilapia species that demonstrate better growth performance. This study reviews and summarises knowledge acquired on S. melanotheron over several decades, paying particular attention to the northern subspecies, S. m. heudelotii. Current research limitations consist of: (i) the status of the species itself, comprising subspecies that are still too poorly characterized; (ii) the interaction between salinity and other parameters, particularly hypoxia; (iii) the impact of climate change on the entire species range, involving multiple environmental parameters in Western Africa; and (iv) limited access to resources in Africa, hindering local and regional development
Plant conservation in a changing Mediterranean world
No full textInternational audienceSocietal Impact Statement The Mediterranean is one of five climatic regions on the planet characterised by a prolonged summer drought, exceptional plant diversity and high rates of endemism. We provide a framework to link the ecology of plant species conservation in the context of rapid and extreme climate deregulation to a philosophical typology of temporal attitudes (i.e., past, present and future). We argue that we must go beyond the historical heritage approach to embrace conservation action in a changing world. We review pragmatic and original ways to deepen social awareness for plant conservation, aligned with the three temporal themes. It is time to bring plants to the forefront of conservation action. Summary In this Thomas Review, we provide a structure that links ecological science of plant species conservation to a philosophical typology of temporal attitudes of scientists, i.e. ways of considering the inscription of one's action in time, with a preference for a temporal dimension in the past, the present or the future. We developed this framework to illustrate original ways of deepening social awareness for plant conservation. In section 1, we widen ecological and evolutionary foundations for plant conservation based on the historical floristic heritage to embrace the need to protect species at their range limits and the need to monitor the effects of extreme climate events. The processes that shape diversity and adaptation are central to this approach. Section 2 describes three temporal attitudes associated with the above three conservation themes. The remembrance attitude is characterised by its interest in the long‐term history of plant diversity. The anticipation attitude relies on climate scenarios and expected species distribution changes. Finally, a prudent attitude consists of making regular observations of ongoing change that relies on an iterative temporality of a continually renewed present. In section 3, we illustrate pragmatic and original ways to deepen social awareness for plant conservation in line with the three temporal themes. We conclude with a comment on the uncertainties surrounding conservation science and the need for confidence to act locally.El Mediterráneo es una de las cinco regiones climáticas del planeta caracterizadas por una prolongada sequía estival, una diversidad vegetal excepcional y altos índices de endemismo. En un contexto de desregulación climática acelerada y extrema, proponemos un marco para vincular la ecología de la conservación de especies vegetales con una tipología filosófica de actitudes temporales (pasado, presente y futuro). Sostenemos que es necesario superar un enfoque rígido centrado en el patrimonio natural y estructurar acciones de conservación adecuadas a un mundo en transformación. Examinamos medios pragmáticos y originales para fortalecer la concientización social sobre la conservación de las plantas en relación con estas tres dimensiones temporales. Ha llegado el momento de situar a las plantas en el centro de las estrategias de conservación.La Méditerranée est l'une des cinq régions climatiques de la planète caractérisées par une sécheresse estivale prolongée, une diversité végétale exceptionnelle et des taux élevés d'endémisme. Dans un contexte de dérégulation climatique accélérée et extrême, nous proposons un cadre pour relier l'écologie de la conservation des espèces végétales, à une typologie philosophique des attitudes temporelles (passé, présent et futur). Nous défendons l'idée qu'il faut dépasser une approche figée du patrimoine naturel et structurer des actions de conservation dans un monde en mutation. Nous passons en revue des moyens pragmatiques et originaux de renforcer la sensibilisation sociale à la conservation des plantes, en lien avec ces trois dimensions temporelles. Le moment est venu de mettre les plantes au cœur des stratégies de conservation.Il Mediterraneo è una delle cinque regioni climatiche del pianeta caratterizzate da una siccità estiva prolungata, un'eccezionale diversità vegetale e alti tassi di endemismo. In un contesto di sregolamento climatico, rapido ed estremo, proponiamo un quadro per collegare l'ecologia della conservazione delle specie vegetali a una tipologia filosofica delle attitudini temporali (passato, presente e futuro). Sosteniamo che occorre superare un approccio statico al patrimonio naturale e strutturare azioni di conservazione in un mondo in trasformazione. Esaminiamo modalità pragmatiche e originali per rafforzare la consapevolezza sociale sulla conservazione delle piante, in relazione a queste tre dimensioni temporali. È giunto il momento di mettere le piante al centro delle strategie di conservazione
Seeing yew for the forest: a call to action for improving conservation and restoration of the European yew (Taxus baccata L.)
No full textInternational audienceThe European yew (Taxus baccata L.) is a long-lived conifer of ecological, cultural, and historical importance across Eurasia. Despite its remarkable resilience, wide distribution, and symbolic importance, the species has experienced a long-term decline due to a complex interplay of climatic fluctuations, megafaunal extinctions, human exploitation, and insufficient regeneration. Recent studies in palaeoecology, archaeology, dendroecology, and conservation have revealed a species with greater ecological plasticity and a broader historical distribution than previously assumed. However, many fundamental questions remain unresolved, particularly regarding its biogeographical history, population dynamics, recruitment processes, and the drivers of its decline.This review stems from prior investigations of yew in the French Pyrenees and, more broadly, across Europe. These efforts led to a transdisciplinary seminar and opened a collaboration uniting >30 researchers across Eurasia. By synthesizing a wide array of data and perspectives, the article highlights key knowledge gaps and outlines emerging research priorities. These are organized thematically—past, present, and future—and include 25 questions on the species' ecological niche, life-history strategies, human interactions, genetic resilience, and conservation under global change. The article advocates for a shift towards integrative and long-term conservation strategies that embrace the historical legacies of yew populations, the general ecology of the species along with local ecological context dependence, and the urgency of future threats. By identifying pressing research needs, this review seeks to lay the foundation for new collaborative initiatives and to support evidence-based conservation of this emblematic yet understudied species
Opinion note on nonlinearity in induced polarization
No full textInternational audienceThe extension of direct current resistivity methods to induced polarization methods has enriched the tools available for subsurface exploration. This enrichment involves an increase in the number of parameters used in the models, as well as addressing different physical phenomena than those observed with direct current. Accounting for nonlinearities, if they exist, can further enhance the sophistication of our models. Nonlinearities are often observed, particularly in laboratory experiments. However, we question their origin, and the experiment described here suggests that the nonlinearities observed under typical experimental conditions may be artifacts related to the electrodes, rather than reflecting the actual response of the subsurface. Indeed, we first replaced the polarizable injection electrodes with non-polarizable electrodes. The nonlinearities observed due to the presence of harmonics were significantly reduced. Then, we replaced the voltage control with a current control, which completely eliminated the nonlinearities still present. We know that it is impossible to prove the non-existence of a phenomenon that does not exist. This fundamental epistemological principle (as pointed out by Russell and Popper) means that we are not claiming that nonlinearity does not exist. We are simply describing an experiment that can raise doubts about its existence
Surface albedo and thermal radiation dynamics under conservation and conventional agriculture in subhumid Zimbabwe
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/614360/) * Autres projets (id;sigle;titre): 101138269;ACCURATE;(EU) Albedo, Conservation agriCUltuRe and climATe bEnefit// FOOD/2021/424–933;RAIZ;(EU) Promoting agroecological intensification for resilience building in Zimbabwe//International audienceWhile conservation agriculture (CA) has been widely evaluated for its biogeochemical effects (e.g soil organic carbon sequestration and greenhouse gas emissions) for climate mitigation, its biogeophysical impacts related to changes in surface albedo remain understudied. This study assessed the biogeophysical effects of CA cropping systems with maize (Zea mays L.) in Zimbabwe. Measurements were conducted continuously over two cropping years at two long-term experiments with contrasting soil characteristics, on an abruptic Lixisol and on a xanthic Ferralsol. The dynamics of surface albedo, longwave radiation, leaf area index, soil moisture and temperature were monitored under three different treatments: conventional tillage (CT, tilled to ~15 cm), no-tillage (NT) and no-tillage with mulch (NTM, 2.5 t DM ha⁻¹). Our results revealed that, on the Ferralsol, NT and NTM significantly (p < 0.05) increased mean annual albedo (0.17) relative to CT (0.16), resulting in a negative instantaneous radiative forcing (iRF) and indicating a net cooling effect. iRF was stronger in 2021/22 (NT: -0.83 ± 0.17 W m-2; NTM: -1.43 ± 0.7 W m-2) than in 2022/23 (NT: -0.43 ± 0.09 W m-2; NTM: -1.03 ± 0.21 W m-2). Conversely, on the Lixisol, while NT increased surface albedo (0.27 vs. CT: 0.24), NTM significantly reduced albedo (0.23), causing positive iRF (warming). iRF was -3.34 ± 0.69 W m-2 and -2.78 ± 0.77 W m-2 for NT in the first and second cropping year, respectively, and increased from 1.14 ± 0.21 W -2 (2021/22) to 2.77 ± 0.41 W m-2 (2022/ 23) under NTM. Overall, our results suggest that the soil background albedo is an important site characteristic that needs to be considered and demonstrates the importance of considering biogeophysical effects when promoting practices of CA for climate change mitigation
Role of behaviour change in controlling the 2022 Paris mpox outbreak
No full textInternational audienceThe 2022 mpox outbreak led to a rapid case surge among men-who-have-sex-with-men (MSM) in previously unaffected regions, followed by a sudden decline, whose drivers remain unclear. We developed a network model of mpox transmission among MSM based on sexual behaviour data, focusing on the Paris region epidemic. Our analysis tested three drivers for the decline: postexposure prophylaxis (PEP) vaccination; immunity among highly active MSM; and behavioural adaptations, either uniform in the population or based on individual risk factors. Behavioural changes adopted by 49% (95% CI 47-51%) of MSM, regardless of risk factors, best explained the decline, preventing an estimated 68% (15-99%) of potential cases in summer 2022. To validate model predictions, we analyzed data from the 2023 ERAS survey and found that 46% (45-48%) of MSM in the region reported reducing their number of sexual partners during that period-closely matching model estimates. In contrast, PEP vaccination and immunity among highly active MSM were insufficient to halt the outbreak. Both model predictions and survey results underscore the role of widespread, spontaneous behavioural adaptations, regardless of risk profile, in driving the epidemic downturn. These findings highlight the importance of effective risk communication and community engagement in outbreak managemen
The evolution of drought characteristics in semi-arid Africa over the last four decades
No full textInternational audiencetudy regionSemi-arid Africa, covering six subregions: the Mediterranean (MED), Sahel, North Eastern Africa (NEAF), South Eastern Africa (SEAF), Southern Africa (SAF), and Madagascar (MDG).Study focusWe analyse drought duration, intensity, and severity from 1979 to 2024 across semi-arid Africa. Using Climate Prediction Center (CPC, 0.5°) precipitation and temperature, we compute the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). Trends are detected with the Mann–Kendall test and Theil–Sen slope estimator. Short-term droughts (3–6 months), strongly influenced by temperature variability, are distinguished from 12-month events driven by cumulative hydrological deficits.New hydrological insightsThree drought episodes emerge: the early 1990s, early 2000s, and the recent period beginning in 2022. Long time-scale indices (SPI-12, SPEI-12) capture the most persistent droughts, whereas short time-scale indices (SPEI-3, SPEI-6) reveal intense temperature-driven episodes. In MED, only 7–25 % of grid cells show significant SPI trends in duration, severity, and intensity, but up to 75 % exhibit drought intensification with SPEI, underscoring strong temperature sensitivity. Across NEAF, SEAF, SAF, and MDG, 25–55 % of pixels show significant increases in drought duration (up to +3 months per decade), severity (+3 units per decade), and intensity (+0.5 units per decade). Parts of the western Sahel and southern Madagascar display decreasing trends. Overall, the study delivers a continent-wide assessment of drought evolution and identifies hotspots where intensifying drought threatens water resources and food security