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Temperature as an early warning signal of honeybee colony failure
No full textInternational audienceHow to identify ecological systems at risk of failure is a central question of modern biology and agriculture. Due to human impacts and global change, there is a growing need for early warning signals that identify when a system is at risk of a state change before changes become irreversible or extremely complex and costly to remediate. Honeybees (Apis mellifera) are an urgent case because our food crops heavily rely on them for pollination and annual bee colony losses reported by beekeepers across the globe are unsustainable. Given enough warning, beekeepers can rescue dying colonies. Here we aim to develop an early warning system for the death of honeybee colonies. We used early warning signals to investigate whether fluctuations and dynamical patterns in internal hive temperature can be used as an early indicator of impending colony failure. Across three distinct datasets, we found that temperature regulation of failing colonies was different enough to distinguish them from healthy colonies before they died. We used a Receiver Operating Characteristic (ROC) approach to compare different predictors and determine the trade-off between sensitivity and specificity in our system. Our study shows that early warning theory can help to identify practical signals of risk of state change even in complex systems that change state relatively rapidly, such as a dying bee colony.</div
A framework to assess the risk of yellow fever emergence
No full textInternational audienceYellow fever (YF) is a viral hemorrhagic fever transmitted by Aedes aegypti mosquitoes. Symptoms range from mild fever to severe complications such as jaundice and haemorrhages, which can be fatal. Martinique, a French island in the Caribbean, has remained YF-free since 1908. However, the reintroduction of A. aegypti in the 1970s, the limited scope of mandatory vaccination—currently required only for international travellers to endemic areas—and increased connectivity to YF-endemic regions heighten its vulnerability. To inform local preparedness activities, we assessed the risk of YF emergence, defined as introduction and establishment, by looking at vector competence of local native species of A. aegypti in Martinique. Methods We developed a framework to evaluate YF emergence risk, integrating multiple contributing factors and taking Martinique as a case study. We used reported cases from 2015 to 2022 to estimate the predicted force of infection in endemic countries and map genotype presence in source countries. In addition, we analyzed flight traffic patterns from 2019 to 2022 and computed genotype-specific transmission efficiency by local mosquito populations. Results Before 2020, Brazil represented the greatest YF introduction risk due to high passenger volumes. However, the moderate transmissibility of the South America II YF virus strain in Martinique’s mosquito populations partially mitigated this risk. The COVID-19 pandemic disrupted global travel, temporarily shifting the risk landscape towards African countries such as Ivory Coast and Cameroon, where the West African strain exhibits higher transmissibility. However, this risk remained limited by the low number of travellers from these regions. Conclusions There are growing concerns about the risk of YF introduction and emergence in non-endemic territories like Martinique. Climate change, mosquito adaptability (e.g. egg resistance to desiccation, winter diapause) and intensified global travel drive this risk. This integrative risk assessment framework supports YF emergence prevention and could be applied to other at-risk territories
Revealing the Fe doping effect on Ni catalysts for low alkalinity OER: from three-electrode systems to continuous flow anion exchange membrane water electrolyser
No full textInternational audienceHere, we report the use of magnetic induction heating as a rapid and efficient synthesis method to produce Fe@Ni nanoparticles (NPs) with tunable surface coverage and their application as catalysts in the oxygen evolution reaction (OER). This approach enables localized thermal decomposition of precursors, offering improved control over catalyst phase formation. To bridge the gap between lab-scale materials and practical electrolyser integration, the catalysts were deposited onto commercially available Ni-mesh supports suitable for Anion Exchange Membrane Water Electrolyser (AEMWE) operation. The influence of iron content on OER activity was evaluated, and the catalyst performance was validated in a full-cell electrolyser, highlighting the potential of this synthesis route for scalable green hydrogen technologies.</div
Direct Development of Golf Ball Sponges, Genus Craniella (Demospongiae, Tetractinellida) From the Northeast Atlantic Ocean
No full textInternational audienceAmong the eight types of development in sponges, the least common and least studied is direct, non‐larval development during viviparity. To supplement our knowledge of this rare type of demosponge development, we present here a description of the embryonic development of four species of the genus Craniella (Demospongiae, order Tetractinellida) from the deep‐sea in the Northeast Atlantic. Craniella development is asynchronous within one sponge. Mature oocytes are polylecithal and isolecithal. Embryonic development occurs in a dense double‐layer follicle: layers of flattened cells and a thick layer of collagen. The cleavage is total, unequal, and asynchronous. It is characterized by collagen layers penetrating inside the embryo and surrounding blastomeres. As a result of cleavage, an oval‐shaped apolar stereoblastula is formed. At the stereoblastula stage, embryonic sclerocytes secrete the first megascleres, long thin oxeas, radially positioned. Later, the embryo is divided into the peripheral, intermediate, and central zones. In the intermediate zone, choanocyte chambers, lacunes, and canals of the aquiferous system are formed. The fully formed juveniles have a subspherical to flattened shape with cone‐shaped outgrowths on the surface. Unlike the adults, juveniles lack cortical microxeas and have characteristic anamonaenes spicules. The juveniles exit the mother's body through the exhalant canals of the aquiferous system. Trial Registration: Not applicabl
Interactions between the perception of agri-environmental performances and multi-Criteria evaluation based on crop model simulations in southwestern france
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Extended treatment of venous thromboembolism with reduced-dose versus full-dose direct oral anticoagulants in patients at high risk of recurrence: a non-inferiority, multicentre, randomised, open-label, blinded endpoint trial
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Etat de conservation du loup en France : mise à jour 2025 de la viabilité démographique de la population sous régime de tirs dérogatoires: Rapport sur saisine inter-ministérielle du 04.12.2024
No full textRapport sur saisine ministérielle du 04.12.2024Ce rapport d'expertise porte sur la viabilité des populations de Loup gris (Canis lupus) en France à l'horizon 2035. Coordonné par l'Office français de la biodiversité (OFB) et le Muséum national d'Histoire naturelle (MNHN) sur saisine interministérielle, il associe une étude prospective des populations à une analyse des impacts des tirs dérogatoires, afin d'évaluer les probabilités d'évolution des effectifs de loups. Les résultats de ces simulations fournissent des informations utiles à la gestion de l'espèce
Small fires, big gap: high-resolution VIIRS data reveal widespread underestimation of emissions in sub-Saharan Africa
No full textInternational audienceFires across sub-Saharan Africa (SSA) are a dominant source of global carbon emissions, yet their true magnitude remains uncertain due to the limitations of coarse-resolution satellite products. In this study, we developed a high-resolution fire emission inventory prototype for SSA using active fire detections from the VIIRS sensor (375 m) and a top-down approach based on fire radiative power (FRP). Emissions were estimated through the integration of FRP to fire radiative energy (FRE), conversion to dry matter burned using biome-specific combustion coefficients, and application of emission factors for carbon dioxide. A parallel MODIS-based dataset was also produced using the same methodology to isolate sensor-specific effects. To evaluate detection and modelling differences, the VIIRS-based product (VIIRS-EM) was compared against six widely used global fire emission inventories. In addition, a subset of emissions from small fires (defined as FRP < 10 MW) was derived and assessed separately. Over the period 2013-2022, VIIRS-EM estimated average annual carbon emissions of 3.0 Pg C, which is 50-75 % higher than most MODIS-based inventories. Emission hotspots were identified in agricultural and savanna regions, particularly in West and Central Africa. Small fires contributed significantly to early and late fire-season emissions and revealed widespread underestimation in existing products. Our findings underscore the importance of high-resolution detection and FRP-based modelling for capturing the full extent of African fire activity. The VIIRS-EM inventory provides improved spatial and temporal resolution, with implications for atmospheric composition modelling, greenhouse gas accounting, and regional fire policy development.</div
Productions sédimentaires d’une crue extrême : exemple des affluents de la Vésubie au cours de la tempête Alex
No full textInternational audienceOn October 2, 2020, Storm Alex triggered one of the most extreme torrential floods in recent years in France, causing severe damage in the Vésubie and Roya valleys (southeastern France). In the Vésubie, the floods induced exceptional sediment yields both in the main river and its tributaries. High-resolution pre- and post-event LiDAR data enabled the construction of a detailed sediment budget at the catchment scale. This study (i) contextualizes the storm-induced torrential event with other documented intense floods across the Alps and worldwide, and (ii) analyses the variability and controlling factors of the specific sediment yield in the Vésubie tributaries. While Storm Alex ranks among the highest sediment yields recorded in the Alps, it is included in the variability domain of extreme headwater sediment production. Integrating these new data with existing Alpine records allows to refine an upper limit (the 99th percentile) for values of extreme sediment yields in the Alps. Variability in measurement methods across the literature underscores the suitability of systematically using high resolution topographic differencing for future extreme torrential events analyses. The observed specific sediment yield variability across the tributaries cannot be explained by rainfall forcings, making sediment availability the dominant control. We demonstrate that the specific sediment yield variability is best predicted by the proportion of sediment sources and the slope at the outlet measured on each catchment.La tempête Alex du 2 octobre 2020 a été à l’origine de l’une des crues torrentielles les plus intenses du XXIe siècle en France, causant d’importants dégâts, principalement dans les vallées de la Vésubie et de la Roya. Dans le bassin de la Vésubie, les crues torrentielles ont entraîné une production sédimentaire exceptionnelle sur les affluents et le fond de vallée. Des données LiDAR pré- et post-événement ont permis la construction d’un bilan sédimentaire détaillé à l’échelle de l’ensemble du bassin versant. Cette étude (i) replace cet événement torrentiel au regard des crues intenses documentées dans les Alpes et dans le monde, et (ii) analyse la variabilité et les facteurs de contrôle de la production sédimentaire spécifique des affluents de la Vésubie. Bien que la tempête Alex figure parmi les plus fortes productions sédimentaires documentées dans les Alpes, elle n’est pas pour autant sans précédent. L’intégration des données de la tempête Alex aux données de la littérature dans les Alpes nous permet d’établir une borne supérieure (99e percentile) robuste de la production sédimentaire des évènements extrêmes à l’échelle des Alpes. La variabilité des méthodes de mesure utilisées dans la littérature démontre la pertinence de généraliser l’utilisation des topographies différentielles haute résolution pour l’étude des futurs évènements extrêmes. Les résultats montrent que la variabilité de la production sédimentaire ne s’explique pas par les forçages pluviométriques, mais est contrôlée par la disponibilité en sédiments de chaque bassin. Enfin, il ressort que la proportion des sources sédimentaires et la pente à l’exutoire calculées à l’échelle des bassins versants sont les meilleurs prédicteurs de la production sédimentaire spécifique
A probabilistic algorithm for gene-species reconciliation with segmental duplications
No full textInternational audienceReconciliations are a mathematical tool to compare the phylogenetic trees of genes to the species that contain them, accounting for events such as gene duplication and loss. Traditional reconciliation methods have predominantly relied on parsimony to infer gene-only evolutionary events, and usually make the hypothesis that genes evolve independently. Recently, more advanced models have been developed that account for complex gene interactions stemming from phenomena such as segmental duplications, where multiple genes undergo simultaneous duplication. In this paper, we study the NP-hard problem of reconciling gene trees to a species tree with segmental duplications, without the aid of synteny information. We address this problem by proposing a novel probabilistic approach, imposing a Boltzmann distribution over the space of reconciliations. This allows for a Gibbs sampling-like Markov chain Monte Carlo algorithm that uses simulated annealing to effectively find or approximate the most parsimonious 1</div