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Aedes albopictus is rapidly invading its climatic niche in France: Wider implications for biting nuisance and arbovirus control in Western Europe
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/615452/) * Autres projets (id;sigle;titre): ;RIVOC;(FRA) Risques infectieux en Occitanie//International audienceThe Asian tiger mosquito, Aedes albopictus, is a competent vector of arboviruses, such as dengue. After its introduction into southern Europe, this invasive species has been rapidly spreading as well as causing autochthonous cases of arboviral diseases. Both Ae. albopictus presence and potential to transmit arboviruses are facilitated at warm temperatures; hence, global warming is expected to affect their presence in temperate regions. We use a climate- and environmental-driven mechanistic modeling framework to investigate the impact of recent climate change on Ae. albopictus range expansion and its potential to transmit dengue in Western Europe. We simulate climatic suitability, adult density, and dengue transmission risk, which we compare with a large ensemble of entomological and epidemiological observations over the past 20 years. Most importantly, we analyze a novel spatiotemporal dataset of colonized municipalities in metropolitan France to estimate the spread rate of Ae. albopictus and compare it with model predictions. Lastly, we analyze the sensitivity of entomological and epidemiological risk to changes in temperature, rainfall, and human density. Distribution of simulated mosquito populations and dengue transmission risk satisfactorily match entomological and dengue observations for Western Europe (AUC = 0.90 and 0.75 respectively). While lowlands in southern Europe were already climatically suitable for hosting Ae. albopictus around 2010, Western France, together with large populated cities, such as London, Zagreb, and Vienna, has become suitable recently. Importantly, the accelerating colonization of Ae. albopictus in France may be approaching the limit of its theoretical climatic niche; future expansion will depend on the climate-driven enlargement of suitable areas. The area at risk of dengue transmission has recently expanded from the Mediterranean coasts over northern Spain and Western France. The sensitivity analysis suggests that climate change may expose medium-sized cities to the highest epidemiological risk; this finding is consistent with recently reported dengue outbreaks in Europe
Major histocompatibility complex class IIB disassortative mate choice in a genetically monogamous seabird
No full textInternational audienceAmong species reproducing sexually, mating strategies represent a major component of individual fitness. The major histocompatibility complex (MHC) is an extremely diverse set of genes responsible for immunological recognition and defence against pathogens. Although dissimilarity between mates at the major histocompatibility complex has been proposed to drive mate choice through increased offspring pathogen resistance, evidence is mixed. In addition, explorations of the role of the major histocompatibility complex in other mating strategies, such as divorce, are rare. We investigated whether dissimilarity at the major histocompatibility complex class IIB is associated with mate choice and divorce probability in the genetically monogamous black-legged kittiwake ( Rissa tridactyla ). We found that first-time male breeders, as well as divorced males, were paired with females more dissimilar at the major histocompatibility complex class IIB than expected under random mating. We did not find evidence for mate choice based on major histocompatibility complex class IIB dissimilarity when considering females. In addition, in the studied population, divorce probability was very low compared with other populations and did not significantly vary with the dissimilarity of the pair at the major histocompatibility complex class IIB. Our results pave the way to a better understanding of the complex role of major histocompatibility complex dissimilarity in mating decisions of species displaying mutual choice and biparental care
Multiple sources of atmospheric CO 2 activated by AMOC recovery at the onset of interglacial MIS 9
No full textInternational audienceUsing high-precision ice core measurements of CO 2 , δ 13 C–CO 2 , CH 4 , and N 2 O, this study provides carbon isotope constraints on a sizeable, centennial-scale CO 2 jump at the onset of Marine Isotope Stage 9 (MIS 9). The very end of the Heinrich stadial (HS) characterizing Termination IV (T-IV, ca. 343 to 333 ka ago) shows a 250-y-long jump in greenhouse gas concentrations, followed by a 1.3 ka gradual decline back to the initial concentration. During this so-called overshoot, CO 2 and CH 4 reach their highest levels (about 303 ppm and 800 ppb, respectively) over the past 800 ka prior to industrialization. The jump in CO 2 is not accompanied by a change in δ 13 C–CO 2, suggesting that multiple mechanisms contributed to the exceptionally elevated CO 2 values. Following the jump, a slow 0.2‰ enrichment in δ 13 C–CO 2 occurs. We propose that during the jump, the sudden resumption of deepwater formation in the North Atlantic (NA) triggered an amplified release of CO 2 from the Southern Ocean (SO) by a northward shift of the Intertropical Convergence Zone (ITCZ) and the SO westerlies, potentially in combination with a rapid land carbon release. The latter is expected from temporally enhanced wildfire activity related to higher fuel load and regionally changing weather conditions in connection to the ITCZ shift. A combination of marine proxy records and box model simulation suggests that the δ 13 C–CO 2 decrease expected from these processes is compensated by a net temperature increase in global sea surface temperature (SST) at the time of the AMOC resumption
Assessment of the southern polar and subpolar warming in the PMIP4 last interglacial simulations using paleoclimate data syntheses
No full textInternational audienceGiven relatively abundant paleo-proxies, the study of the last interglacial (LIG, ∼ 129–116 000 years ago, ka) is valuable to understanding the responses and feedback of the Southern Ocean and Antarctica in a warmer-than-preindustrial climate. The Paleoclimate Modelling Intercomparison Project Phase 4 (PMIP4) coordinated LIG model simulations which focus on 127 ka. Here we evaluate 12 PMIP4 127 ka Tier 1 model simulations against four recent paleoclimate syntheses of LIG sea and air temperatures and sea ice concentrations. The four syntheses include 99 reconstructions, and all syntheses support the presence of a warmer Southern Ocean, with reduced sea ice and a warmer Antarctica at 127 ka compared to the preindustrial. The PMIP4 127 ka Tier 1 simulations, forced solely by orbital parameters and greenhouse gas concentrations, do not capture the magnitude of this warming. Here we follow up on previous work that suggests the importance of preceding deglaciation meltwater release into the North Atlantic for the early last interglacial climate. We run a 3000-year 128 ka simulation using HadCM3 with a 0.25 Sv North Atlantic freshwater hosing, which approximates the PMIP4 127 ka Tier 2 H11 (Heinrich event 11) simulation. The hosed 128 ka HadCM3 simulation captures much of the warming and sea ice loss shown in the four data syntheses at 127 ka relative to preindustrial: south of 40° S, modeled annual sea surface temperature (SST) rises by 1.3 ± 0.6 °C, while reconstructed average anomalies range from 2.2 to 2.7 °C; modeled summer SST increases by 1.1 ± 0.7 °C, close to the 1.2–2.2 °C reconstructed average anomalies; September sea ice area (SIA) is reduced by 40 %, similar to the reconstructed 40 % reduction of sea ice concentration (SIC); over the Antarctic Ice Sheet, modeled annual surface air temperature (SAT) increases by 2.6 ± 0.4 °C, even larger than reconstructed average anomalies of 2.2 °C. Our results suggest that the impacts of meltwater from deglaciating ice sheets need to be considered to simulate the Southern Ocean and Antarctic changes at 127 ka
Estimating Marginal Likelihoods in Likelihood-Free Inference via Neural Density Estimation
No full textThe marginal likelihood, or evidence, plays a central role in Bayesian model selection, yet remains notoriously challenging to compute in likelihood-free settings. While Simulation-Based Inference (SBI) techniques such as Sequential Neural Likelihood Estimation (SNLE) offer powerful tools to approximate posteriors using neural density estimators, they typically do not provide estimates of the evidence. In this technical report presented at BayesComp 2025, we present a simple and general methodology to estimate the marginal likelihood using the output of SNLE
Can citizen science fill knowledge gaps for the world’s most speciose and poorly-known insular amphibian fauna?
No full textInternational audienceContext: Tropical regions host the richest, yet most poorly known and threatened concentrations of biodiversity on the planet. Citizen science is increasingly viewed as a strategy to help fill these key data gaps. However, inadequate taxonomic frameworks, social inequities, and poor infrastructure may all constrain this potential. Aims. To examine how effectively citizen science data from iNaturalist fills gaps in knowledge about the distribution, species richness and conservation status of a megadiverse tropical biota, namely the frogs of Melanesia (New Guinea and nearby islands).Methods: We identified all records of Melanesian frogs on iNaturalist to species or genus where possible. Species distributions on iNaturalist were then compared to existing distribution maps and records to identify range extensions, and the IUCN Red List conservation status of any species not currently considered Least Concern was assessed based on new distributional information. Key results. We estimate that around 125 described Melanesian frog species (23% of the total fauna) have been recorded on iNaturalist, including putative range extensions for at least 42 species. Based on these new data we recommend updating IUCN Red List assessments for nearly 20 previously Not Evaluated, Data Deficient, or Vulnerable species. Many records cannot be identified to species, and this issue is compounded by a mismatch between the area best-known scientifically (Papua New Guinea) and the area from which the majority of citizen science records originate (Indonesia).Conclusions: Citizen science has clear potential to fill some key knowledge gaps for poorly-known tropical biotas, but does not obviate the need for baseline survey and taxonomic work based on voucher specimens with associated tissues. Implications. Based on our experience, we make recommendations that may increase the impact of citizen science data for poorly-known biotas.Abstrak (Bahasa Indonesia) Konteks Wilayah tropis memiliki konsentrasi keanekaragaman hayati yang paling kaya, tetapi paling sedikit diketahui dan paling terancam di planet ini. Citizen science semakin dianggap sebagai strategi untuk membantu mengisi beberapa kesenjangan data ini, namun belum cukupnya kerangka taksonomi, kesenjangan social, dan infrastruktur yang buruk mungkin menghambat potensi ini. Tujuan Kami memeriksa kefektifan data Citizen science dari iNaturalist dalam mengisi kesenjangan pengetahuan tentang distribusi, kekayaan jenis, dan status konservasi biota tropis yang sangat beragam, yaitu Katak dari Papua Nugini dan pulau-pulau terdekatnya (Melanesia). Metode Jika memungkinkan, kami mengidentifikasi semua catatan katak Melanesia di iNaturalist hingga pada level jenis atau marga. Sebaran jenis pada iNaturalist kemudian dibandingkan dengan peta dan catatan distribusi yang ada untuk mengidentifikasi perluasan wilayah sebaran, dan jenis apa pun yang saat ini tidak dianggap sebagai risiko rendah dalam status konservasi jenis di daftar merah IUCN dinilai berdasarkan informasi distribusinya terbaru. Hasil utama Kami memperkirakan bahwa sekitar 125 jenis Katak Melanesia yang telah dideskripsikan (23% dari total fauna) telah tercatat di iNaturalist, termasuk perluasan potensi sebaran untuk setidaknya 42 jenis. Berdasarkan data baru ini, kami merekomendasikan status konservasi IUCN yang diperbarui untuk hampir 20 jenis yang sebelumnya Tidak Dinilai, Kurang Data, atau Rentan. Banyak catatan tidak dapat diidentifikasi hingga ke jenis, dan masalah ini diperparah oleh ketidakcocokan antara wilayah yang paling dikenal secara ilmiah (Papua Nugini) dan wilayah asal sebagian besar catatan citizen science (Indonesia). Kesimpulan Citizen science memiliki potensi yang jelas untuk mengisi beberapa kesenjangan pengetahuan utama untuk biota tropis yang kurang dikenal, tetapi tidak menghilangkan kebutuhan akan survei dasar dan pekerjaan taksonomi dengan spesimen voucher. Implikasi Berdasarkan pengalaman kami, kami membuat beberapa rekomendasi spesifik yang dapat meningkatkan dampak data citizen science untuk biota yang kurang dikenal
Plant mobile domain protein–DNA motif modules counteract Polycomb silencing to stabilize gene expression
No full textInternational audienceIn plants and animals, Polycomb group (PcG) proteins are crucial for development, regulating gene expression through H3K27me3 deposition and subsequent gene silencing. While Polycomb silencing target specification is increasingly understood, it remains unclear how certain genes with apparent silencing-attracting features escape this process. Here, we show that the plant mobile domain C (PMD-C) containing proteins MAINTENANCE OF MERISTEMS (MAIN), MAIN-LIKE 1 (MAIL1) and MAIL2 oppose Polycomb silencing at numerous actively transcribed genes in Arabidopsis. Mutations in MAIN, MAIL1 or MAIL2 result in PcGdependent ectopic H3K27me3 deposition, often associated with transcriptional repression. We show that MAIL1, which functions in concert with MAIN, and MAIL2 target distinct gene sets and associate with chromatin at specific DNA sequence motifs. We demonstrate that the integrity of these motif sequences is essential for promoting expression and antagonizing H3K27me3 deposition. Our results unveil a novel system opposing Polycomb silencing involving PMD-C protein-DNA motif modules, expanding our understanding of eukaryotic gene regulation mechanisms
Productivity Drives Leaf Mycobiome Diversity Patterns at Global and Continental Scales
No full textInternational audienceAim : Studies assessing large‐scale patterns of microbial diversity have predominantly focused on free‐living microorganisms, often failing to link observed patterns to established theories regarding the maintenance of global diversity patterns. We aimed to determine whether foliar fungi on two closely related grass hosts— Heteropogon contortus and Themeda triandra —display a commonly observed latitudinal gradient in species richness and determine whether host identity, energy (temperature and precipitation), climate seasonality, fire frequency and grass evolutionary history drive the observed patterns in species richness and composition.Location : Paleotropical.Time Period : Contemporary. Major Taxa Studied : Foliar fungi.Methods : Foliar fungal diversity was quantified from 201 leaf samples of T. triandra and H. contortus collected across the distributional range of these species. Mixed effects models were used to quantify patterns of diversity and their correlates among and within continents. Ordinations were used to assess drivers of composition. Results : Foliar fungi displayed consistent latitudinal diversity gradients in richness. Energy was a strong driver of richness at inter‐continental and continental scales, while other factors had inconsistent impacts on richness among scales, hosts and guilds. Globally, richness was higher in regions of higher growing season temperatures and where hosts were present for longer periods. Composition was primarily structured by geographic region at the global scale, indicating that distance was a dominant driver of community composition. Within Australia, temperature and rainfall seasonality and the amount of growing season rainfall, were the dominant drivers of both richness and composition.Main Conclusions : We find some support for the idea that foliar fungal species diversity is governed by the same factors as many macro‐organisms (energy availability and evolutionary history) at inter‐continental scales, but also that fungal diversity and composition in the highly seasonal continent of Australia were driven by factors that shape tropical grassy ecosystems, namely climate seasonality and fire
Exploring Bird Gut Microbiota Through Opportunistic Fecal Sampling: Ecological and Evolutionary Perspectives
No full textInternational audienceWetland ecosystems are facing alarming rates of destruction and degradation, posing significant challenges for avian populations reliant on these habitats. Bird health is closely linked to the composition of their intestinal microbiota, which is primarily influenced by local conditions, primarily through diet. Building on our previous work identifying dietary variations among bird populations in marshes within a Ramsar site along the Somme and Avre rivers (France), this pilot study aimed to assess the relevance of using fecal samples collected from the ground to characterize avian intestinal microbiota via 16S rRNA metabarcoding. We hypothesized that this noninvasive sampling method would capture how bird traits and environmental factors shape fecal microbiota composition. Sampling was conducted during the breeding season at seven locations (six within the Ramsar site and one on its outskirts) spanning rural or peri‐urban environments. A total of 52 fecal samples from nine bird species or families, predominantly waterbirds, were analyzed for bacterial composition. At the phylum level, Firmicutes and Proteobacteria were predominant, with the relative abundance of genera such as Clostridium , Rothia , Bacillus , Caldilinea and Pseudomonas varying among bird species. The potential enteropathogen Campylobacter was primarily detected in samples from peri‐urban sites. Multivariate analyses revealed significant variations in bacterial composition associated with bird trophic guild, ecology, body length, pond surface and habitat location. Additionally, a weak correlation was observed between host phylogeny and microbiota composition. Although the limited sample size, particularly for some species, constrains the robustness of these findings, the observed trends align with ecological expectations. This study highlights the potential of opportunistically collected fecal samples as a low‐impact tool for exploring the relationship between bird gut microbiota and their habitat
Advanced phycocyanin detection in a south American lake using landsat imagery and remote sensing
No full textInternational audienceIn this study, multispectral images were used to detect toxic blooms in Villarrica Lake in Chile, using a time series of water quality data from 1989 to 2024, based on the extraction of spectral information from Landsat 8 and 9 satellite imagery. To explore the predictive capacity of these variables, we constructed 255 multiple linear regression models using different combinations of spectral bands and indices as independent variables, with phycocyanin concentration as the dependent variable. The most effective model, selected through a stepwise regression procedure, incorporated seven statistically significant predictors (p < 0.05) and took the following form: FCA = N/G + NDVI + B + GNDVI + EVI + SABI + CCI. This model achieved a strong fit to the validation data, with an R2 of 0.85 and an RMSE of 0.10 μg/L, indicating high explanatory power and relatively low error in phycocyanin estimation. When applied to the complete weekly time series of satellite observations, the model successfully captured both seasonal dynamics and interannual variability in phycocyanin concentrations (R2 = 0.92; RMSE = 0.05 μg/L). These results demonstrate the robustness and practical utility for long-term monitoring of harmful algal blooms in Lake Villarrica