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The geographical distribution of all species of the genus is completed through the study of new material present in various collections (932 specimens). Distribution maps are presented and a summary of ecological data is provided based on label informations, mainly collecting methods and altitudes. The genus is found for the first time from Belize, with D. penatii and D. pusillus. D. hielkemai is probably the species with the largest distribution. C. barberoi, C. bihamatus and D. yvesi show disjunct distributions but probably not for the same reasons. As most species were found under 500 m of altitude, D. diquis, D. pseudohamatus and D. yvesi were collected mainly between 1000 and 2000 m. D. lewisi in Bolivia and D. peruvianus in Peru were collected mainly higher than 2000 m. As most specimens were trapped by FIT, eight species were collected sifting forest litters, and D. antoinei and D. hielkemai were also found through canopy fogging. D. antoinei, D. hielkemai and D. striatus were occasionally found in refuse piles of army ants or leafcutter ants., La distribution géographique des espèces est précisée grâce à l'étude d'un nouveau matériel issu de diverses collections. Des cartes de distribution sont présentées et une synthèse des données écologiques est fournie d'après les renseignements présents sur les étiquettes.

A preliminary investigation of the flora of parasitic microfungi on land plants is reported, focused upon the mountain and the base of the subalpine ranges, in Champsaur region, (south-western French Alps, mainly within the “Parc National des Ecrins”). Sheltered by 128 host-plant species, 182 species of microfungi have been identified. Their respective distributions, among 24 investigated localities (including four located within the Central Zone of the “Parc National des Ecrins”), are specified. Moreover, seven of these 182 microfungi do not match satisfactorily any of the consulted diagnosis in the specialized literature. Accordingly, a detailed description of the main distinctive traits that singularize each of these seven newly highlighted microfungi is provided., Il est rendu compte d’une investigation préliminaire des micromycètes parasites de plantes sauvages aux étages montagnard et base du subalpin dans la région du Champsaur, et plus particulièrement au sein du Parc National des Ecrins (Alpes françaises sud-occidentales). Hébergées par 128 espèces végétales hôtes, 182 espèces de micromycètes ont été inventoriées. Leurs distributions respectives parmi les 24 localités investiguées (dont quatre en Zone Centrale du Parc National) sont précisées. Par ailleurs, sept de ces 182 micromycètes, ne répondent à aucune des diagnoses consultées dans la littérature spécialisée et, conséquemment, chacun d’eux fait l’objet d’un descriptif détaillé des principaux caractères distinctifs qui le caractérisent.

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51 ème congrès du Groupe Français de Recherches sur les Pesticides 31 mai-1 er juin 2023, Paris

Living in variable and unpredictable environments, organisms face recurrent stressful situations. The endocrine stress response, which includes the secretion of glucocorticoids, helps organisms to cope with these perturbations. Although short-term elevations of glucocorticoid levels are often associated with immediate beneficial consequences for individuals, long-term glucocorticoid elevation can compromise key physiological functions such as immunity. While laboratory works highlighted the immunosuppressive effect of long-term elevated glucocorticoids, it remains largely unknown, especially in wild animals, whether this relationship is modulated by individual and environmental characteristics. In this study, we explored the co-variation between baseline cortisol levels, assessed non-invasively using faecal cortisol metabolites (FCMs), and 12 constitutive indices of innate, inflammatory, and adaptive immune functions, in wild roe deer living in three populations with contrasting environmental conditions. Using longitudinal data on 564 individuals, we further investigated whether age and spatio-temporal variations in the quantity and quality of food resources affect the relationship between FCMs and immunity. Negative covariation with glucocorticoids was evident only for innate and inflammatory markers of immunity, while adaptive immunity appeared to be positively or not linked to glucocorticoids. In addition, the negative covariations were generally exacerbated, or revealed, in individuals facing harsh environmental constraints and in old individuals. Therefore, our results highlight the importance of measuring multiple immune markers of immunity in individuals from contrasted environments to unravel the complex relationships between glucocorticoids and immunity in wild animals. Our results also help explain conflicting results found in the literature and could improve our understanding of the long-term consequences of elevated glucocorticoid levels on disease spread and population dynamics.

National audience

Companies must go beyond a purely instrumental conception of biodiversity management to integrate the interactions between the biodiversity of ecosystems and the singularity of human societies into their corporate social responsibility policies., Les entreprises doivent dépasser une conception purement instrumentale de la gestion de la biodiversité pour intégrer au sein des politiques de responsabilité sociétale d’entreprise les interactions entre biodiversité des écosystèmes et singularisme des sociétés humaines.

A new species Bothriurus andorinhas n. sp. is described from an area of transition between savanna-like formations and wet-forests in the south of the state of Pará in Brazil. The new species can be associated with other species of what can be defined as the Bothriurus rochai complex. The description of this new species attests once again about the existence of micro-endemic populations within different groups of Bothriurus. Comments are proposed on some ecological particularities of the micro-habitat of the new taxon and about the region where the new species was discovered in the state of Pará., Une nouvelle espèce, Bothriurus andorinhas n. sp. est décrite d’une zone de transition entre des formations de type savanicole et des forêts humides, situées dans le sud de l’état du Pará au Brésil. La nouvelle espèce peut être associée à d’autres espèces appartenant à un complexe qui peut être défini comme celui de Bothriurus rochai. La description de la nouvelle espèce apporte un nouveau soutien à l’existence de populations micro-endémiques au sein des différents groupes de Bothriurus. Des commentaires sont proposés sur certaines particularités écologiques du micro-habitat du nouveau taxon ainsi que sur la région où la nouvelle espèce a été trouvée au sud de l’état du Pará.

Habitat fragmentation is one of the major threats to biodiversity. The main causes are due to human activity. It is produced by increased urbanisation, agriculture, deforestation, or transport infrastructure. Habitat fragmentation is characterised by a decrease in the amount of favourable habitat and by the isolation of this habitat. The objective of this thesis is to better understand its effect at several scales, from the population level by looking at inter-individual differences linked to different dispersal strategies, to the community and metacommunity level by observing their composition. Several approaches are used: theory, an empirical study and field observations. Dispersal is a key life-history trait for survival in a fragmented habitat as it allows the movement of individuals from one fragment to another and the colonisation of empty fragments. However, several forces have opposing effects on the maintenance of species in a fragmented habitat. Fragmentation increases the costs of dispersal in an unfavourable habitat, increases heterogeneity and competition between relatives. Habitat fragmentation has an impact at the community level by changing the number of species or the composition of communities. Ants are good models to study because they are present in many contrasting environments and have a strong dispersal polymorphism. There are winged queens that disperse alone over long distances, or apterous queens that disperse accompanied by a group of workers over shorter distances. At the population level, I studied the ant Myrmecina graminicola which advantageously uses both dispersal strategies. At the community level, I studied ant species in Parisian parks, a highly fragmented habitat, and in forests near Paris, a less fragmented habitat. In the first chapter, I showed with a theoretical approach that the dispersal distance increases when the habitat fragmentation increases in a context of competition/colonisation trade-off. Habitat structure can strongly affect these results with a decrease of the dispersal when the habitat is aggregated. In a second chapter, I highlighted the existence of this competition/colonisation trade-off in M. graminicola and the importance of the presence of workers during the foundation of a new colony, their presence increasing the survival and growth of the colony. In a third chapter, I showed a decrease in dispersal with increased habitat fragmentation in urban environments in M. graminicola, suggesting that the cost of dispersing in highly fragmented urban environments selects against dispersal. Finally, I observed an increase in species richness, with very different ant communities, between urban and forest environments and a decrease in species richness with increasing park size in the city. There is no effect of fragmentation in forests. This thesis shows the diversity of responses to habitat fragmentation, both at the population and community levels, and opens the way for further studies., La fragmentation de l’habitat est une des menaces majeures qui pèse sur la biodiversité. Les principales causes sont dues à l’activité humaine. Elle est produite par l’augmentation de l’urbanisation, de l’agriculture, de la déforestation ou des infrastructures de transport. La fragmentation de l’habitat est caractérisée par une diminution de la quantité d’habitat favorable et par un isolement de cet habitat. L’objectif de cette thèse est de mieux comprendre son effet à plusieurs échelles, de la population en regardant les différences inter-individuelles notamment liées aux différentes stratégies de dispersion, et à l’échelle des communautés et des métacommunautés en observant leurs compositions. Plusieurs approches sont utilisées : théorie, étude empirique et observations sur le terrain. La dispersion est un trait d’histoire de vie clé pour la survie dans un habitat fragmenté car elle permet le passage d’individus d’un fragment à un autre et la colonisation des fragments vides. Cependant, plusieurs forces ont des effets opposés sur le maintien des espèces dans un contexte de fragmentation de l’habitat. La fragmentation augmente les coûts liés à la dispersion dans un habitat défavorable, augmente l’hétérogénéité mais également la compétition entre apparentés. La fragmentation de l’habitat a un impact à l’échelle des communautés en faisant varier le nombre d’espèces ou la composition de celles-ci. Les fourmis sont de bons modèles d’études pour répondre aux problématiques de cette thèse car elles sont présentes dans de nombreux milieux contrastés et ont un fort polymorphisme de dispersion. Il existe des reines qui dispersent sur de longues distances en étant ailées et seules, ou des reines qui dispersent sur de plus courtes distances en étant aptères et accompagnées d’un groupe d’ouvrières. A l’échelle des populations, j’ai étudié la fourmi graminicole Myrmecina graminicola qui a l’intérêt d’utiliser les deux stratégies de dispersion. A l’échelle des communautés, je me suis intéressé aux espèces de fourmis des parcs parisiens, habitat très fragmenté, et des forêts proches de Paris, habitat peu fragmenté. Dans le premier chapitre, j’ai montré avec une approche théorique que la distance de dispersion augmente quand la fragmentation de l’habitat augmente dans un contexte de compromis compétition/colonisation. Cependant la structuration de l’habitat peut fortement affecter ces résultats avec une diminution de la dispersion quand l’habitat est agrégé. Dans un deuxième chapitre, j’ai mis en évidence l’existence de ce compromis compétition/colonisation chez M. graminicola et l’importance de la présence d’ouvrières lors de la fondation d’une nouvelle colonie, leur présence augmentant la survie et la croissance de la colonie. Dans un troisième chapitre, j’ai montré une diminution de la dispersion avec l’augmentation de la fragmentation de l’habitat en milieu urbain chez M. graminicola, suggérant que le coût à la dispersion en milieu urbain fortement fragmenté sélectionne contre la dispersion. Pour finir, j’ai observé une augmentation de la richesse spécifique, avec des communautés de fourmis très différentes, entre le milieu urbain et forestier et une baisse de la richesse spécifique avec la taille du parc en ville. Il n’y a pas d’effet de la fragmentation en forêt. Cette thèse montre la diversité des réponses à la fragmentation de l’habitat, que ce soit à l’échelle des populations et des communautés, et ouvre la voie à de nouvelles études.

International audience; Le Néolithique voit la domestication de l'Orge au Proche-Orient et sa diffusion progressive jusque dans l'ouest du Bassin Méditerranéen. Elle y représente depuis une céréale majeure des systèmes agraires. Deux sous-espèces coexistent, Orge à 2 rangs (H. v. subsp.distichum) et à 6 rangs (H. v. subsp.vulgare), subdivisées en formes nues et vêtues, en lien avec des usages et caractéristiques agronomiques variés.Les dynamiques passées de cette diversité sont peu connues car les approches paléogénétiques qui permettraient de les appréhender sont fortement limitées par la carbonisation qui, tout en assurant la conservation de la plupart des grains archéologiques, détruit l’ADN. L’essor de la morphométrie géométrique en bioarchéologie procure cependant une série d’outils applicables à grande échelle pour décrire et étudier quantitativement la diversité de l’Orge au cours du temps. Cette étude a pour but (1) de comparer les diversités passée et actuelle de l’Orge, (2) d’en documenter la diversité depuis le Néolithique dans le Sud de la France et le Nord-Est de l’Espagne, (3) d’envisager des relations entre les dynamiques de cette diversité et des évolutions socioéconomiques, culturelles et environnementales. Cette étude repose sur la création d’un référentiel de 85 variétés actuelles carbonisées en laboratoire. Les vues latérale et ventrale de 3347 grains ont été photographiées, puis des Transformées Elliptiques de Fourier ont été calculées à partir des contours de ces grains. Les résultats morphométriques indiquent que, malgré les déformations induites par la carbonisation, la diversité de l’orge peut être documentée par l’analyse des variables de taille, de conformation et de forme des caryopses. Ces résultats ont ensuite permis de s’intéresser aux orges archéologiques. Pour cela, 11633 caryopses archéologiques provenant de 103 sites ont été pris en photo puis analysés. Les résultats montrent que le Néolithique semble se séparer des autres phases chronologiques par les tailles et formes des grains. En effet, on note une diminution durant cette période de leurs longueurs, largeurs et épaisseurs alors que ces variables augmentent depuis la fin du Néolithique jusqu’à l’actuel. Enfin la morphométrie a permis de documenter des différences de taille et de forme entre sites au cours de certaines phases chronologiques qui peuvent s’expliquer de manière multifactorielle. Ces résultats soulèvent des questions sur les dynamiques de la diversité au cours du temps en lien avec des variations climatiques, des différences de terroirs, des pratiques agricoles dont la sélection agronomique, et les choix culturels des populations. Cette étude fait partie du projet DEMETER (ERC Starting Grant #852573, 2020-2025, PI A. Evin) qui a pour but de caractériser l’évolution des espèces domestiques dans le Nord-Ouest du Bassin Méditerranéen Occidental du Néolithique à nos jours, et d’identifier les facteurs culturels, socioéconomiques et environnementaux ayant façonné cette agrobiodiversité et son évolution.

Les grands lacs de la région Auvergne-Rhône-Alpes, représentent des enjeux sociétaux en termes de tourismes, de patrimoine à la fois au niveau régional mais aussi au niveau national étant les plus grandes étendues d’eau douce de France. Ces lacs fournissent de nombreux services écosystémiques comme la ressource en eau, le tourisme, la biodiversité et la pêche. Les lac péri-alpins disposent d’un important potentiel halieutique marqués par des populations de poissons qui constituent une ressource renouvelable exploitées depuis longtemps par la pêche professionnelle et amateur. Au cours des années 1960-80, la dégradation des écosystèmes lacustres s’est accentuée par des pressions anthropiques importante (croissance démographique, développement industriel et agricole) entrainant une eutrophisation des eaux. L’eutrophisation est un processus d’enrichissement de l’eau en éléments nutritifs comme le phosphore conduisant à une forte croissance des plantes et algues. L’eutrophisation a impacté le recrutement naturel des salmonidés lacustres (omble chevalier et corégone) en raison de la prolifération et la décomposition algal entrainant une faible concentration en oxygène dissous et une sédimentation accrue des frayères affectant la survie des œufs. Ces facteurs limitant ont eu pour conséquence le déclin des populations et une chute drastique des captures causant de grandes pertes économiques sur l’ensemble de la chaîne d’exploitation halieutique. Dès 1983, en complémentarité avec la restauration de la qualité des eaux, la Station d’Hydrobiologie Lacustre de l’INRA (Institut national de la recherche agronomique), les pêcheurs et services de l’État ont développé un programme de recherche appliquée portant sur l’amélioration et l’optimisation des repeuplements de salmonidés nommé le « pacage lacustre ». Ce projet de gestion vise à effectuer des déversements de juvéniles de manière contrôlée et optimisée afin de contrebalancer le faible recrutement des juvéniles dans le milieu naturel. L’effort de recherche de l’INRA et les collaborations entre les services, ont permis d’apporter un bon diagnostic et la maîtrise de l’élevage du corégone et de l’omble chevalier contribuant à leur réhabilitation et le maintien de leur population dans les lacs péri-alpins.

Spatial heterogeneity is a fundamental feature of ecosystems, and ecologists have identified it as a factor promoting the stability of population dynamics. In particular, differences in interaction strengths and resource supply between patches generates an asymmetry of biomass turnover with a fast and a slow patch. The coupling of these two energy channels by mobile predators has been identified to increase stability at different scales by promoting the asynchrony of population dynamics between each patch. Here, we demonstrate that asymmetry has a contrasting effect on the stability of metacommunities receiving localised perturbations. We built a model of an asymmetric metacommunity with two patches linked by the dispersal of predators and in which prey receive stochastic perturbations only in one patch. Perturbing prey in the fast patch synchronises the dynamics of prey biomass between the two patches and destabilises predator dynamics by increasing their temporal variability. Conversely, perturbing prey in the slow patch decreases the synchrony of their dynamics and stabilises predator dynamics. This discrepancy between the responses is due to the asymmetric transmission of perturbations caused by the different distributions of biomass between the fast and the slow patch. Consequently, the fast patch drives the dynamics of the metacommunity and imposes synchrony while the slow patch does not. Therefore, local perturbations can have opposite consequences at the regional scale depending on the characteristics of the perturbed patch. Our results have strong implications for conservation ecology and suggest reinforcing protection policies in fast patches to dampen the effects of perturbations and promote the stability of population dynamics at the regional scale.

International audience

Although parasite infection and pollution are common threats facing wild populations, the response of the gut microbiota to the joint impact of these stressors remains largely understudied. Here, we experimentally investigated the effects of exposure to Polycyclic Aromatic Hydrocarbons (PAHs) and infection by a common acanthocephalan intestinal parasite (Pomphorhynchus sp.) on the gut microbial flora of a freshwater fish, the European chub (Squalius cephalus). Naturally infected or uninfected individuals were exposed to PAHs at environmentally realistic concentrations over a five-week period. Characterization of the gut bacterial community through 16S rRNA gene amplicon sequencing revealed that parasitic infection was a more structuring factor of bacterial diversity and composition than PAH exposure. Specifically, chub infected by Pomphorhynchus sp. harbored significantly less evenly represented gut bacterial communities than the uninfected ones. In addition, substantial changes in sequence abundance were observed within the main bacterial phyla, including the Firmicutes, Fusobacteriota, Actinobacteriota, and Proteobacteria. Again, these compositional changes correlated with host infection with Pomphorhynchus sp., confirming its pivotal role in gut microbial assemblage. Overall, these results highlight the importance of defining the parasitic status of individuals when conducting microbial ecotoxicological analyses at the digestive tract level, as this should lead to better understanding of microbiota modulations and help to identify microbial markers specifically associated with chemicals.

The role of earthworms on biogeochemical carbon cycling is a major knowledge gap resulting from the difficulty of isolating and exploring the effects provided by the diversity of organisms. In this study, we investigated the effect of six earthworm species belonging to three ecological categories on soil organic carbon (SOC) mineralisation. To this end, we produced casts with the six species using subsoil material with low SOC content and miscanthus litter. Cast were subjected to laboratory ageing for 140 days. During this process, we monitored physicochemical parameters, CO2 emissions and determined the micro-scale organisation of the casts’ particulate organic matter and pores using X-ray tomography.Our results showed contrasting properties of fresh casts from the 3 main ecological categories, in accordance with the earthworm species’ morphological or behavioral strategies, indicating that those were maintained in artificial environments. However, species-specific changes in cast properties throughout ageing increased intragroup variability among ecological categories. As a result we observed earthworm species-specific evolution of CO2 mineralisation rates during casts ageing. We found that at least half of the variability in CO2 emissions was explained by cast microstructural changes, related to the spatial arrangement between particulate organic matter, porosity, and mineral particles. We conclude that earthworm species-specific traits may play a role in organic carbon protection through their impact on microstructural cast properties.

International audience

Phosphatidylinositol 4-kinases (PI4Ks) are the first enzymes that commit phosphatidylinositol into the phosphoinositide pathway. Phosphoinositides (PPI), minor components of plasma membrane, are the phosphorylated derivatives of phosphatidylinositol (PI), such as phosphatidylinositol-4-phosphate (PI4P) and phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). In the Arabidopsis thaliana genome, twelve putative PI4K isoforms have been identified. Eight belong to type-II (AtPI4Kγ1-8), and four belong to type-III (AtPI4Kα1 and α2 and AtPI4Kβ1 and β2).To study the role of PI4Ks, I have worked with a double mutant defective plant in both the PI4Kβ genes. I show that the Arabidopsis thaliana pi4kβ1β2 double mutant exhibits several root phenotypes: impaired root growth, a lower sensitivity of roots to exogenous IAA (indole-3-acetic acid), impaired gravistimulation, and misshapen root hair growth. These changes appeared to coincide with a less stable actin cytoskeleton and an alteration in intracellular trafficking dynamics in pi4kβ1β2 roots. The content of bioactive auxin in the pi4kβ1β2 roots was similar to that in wild-type ones. Yet, an enhanced auxin-conjugating activity was detected and the auxin level reporter DII-VENUS did not respond to exogenous auxin in pi4kβ1β2 mutant. These data, therefore, link altered PI4K activity to the modification of vesicular trafficking and actin filaments organization one the one hand to altered auxin response likely due to alteration in auxin homeostasis one the other hand.The second part of my thesis was related to the Blumeria graminis (Bgh) interaction with pi4kβ1β2 double mutant. It is known that Arabidopsis has non-host resistance to Bgh. It means that plants build a special resistance structure - papillae - that acts as a barrier between fungi and plant cells. The pi4kβ1β2 double mutant showed an enhanced successful penetration of Bgh 24 hpi. The sid2 mutation affects the ISOCHORISMATE SYNTHASE 1 gene necessary for the synthesis of salicylic acid (SA). A similar defect in penetration resistance was seen in sid2/pi4kβ1β2, indicating the SA-independent character of this phenomenon. Deficiency of PI4Kbetas led to decreased accumulation of PI4P level in papillae. During pathogen attack, plenty of phospholipids and proteins were shown to accumulate in papillae. My hypothesis was that PI4Ks are essential for plant successful defense against Bgh, and more specifically for the formation of a successful papilla.The third part of my thesis concerns the mechanism leading to a constitutively active immunity in pi4kβ1β2 double mutant. In 4-week-old pi4kβ1β2 plants, an accumulation SA occurs. This SA accumulation was shown to be responsible for the dwarf stature of 4-week-old pi4kβ1β2 plants. The question is therefore to understand why the immunity system is constitutively switched on. The immunity system could be activated through cell-membrane or nuclear localized receptors. To study the role of type β PI4Ks in the regulation of defense mechanisms, I first crossed the pi4kβ1β2 double mutant with several mutants affected in different receptors or regulators of immunity. The use of different types of receptors or regulators of immunity will cover a wide range of pathways associated with the both - cell-surface and intracellular immunity. As a control, I used the sid2/pi4kβ1β2 triple mutant that does not accumulate SA, in contrast to pi4kβ1β2 plants. For phenotype describing rosette size was measured. After that typical immunity features were tested: resistance level to hemibiotroph Pseudomonas syringae pv tomato DC3000, PR1 expression and callose accumulation level. If any of these receptors/regulators is upstream to SA accumulation, I hoped to obtain a reverted plant phenotype with wild-type features. The dwarf pi4kβ1β2 phenotype was preserved for all mutants except one - wrky70/pi4kβ1β2, which indicates a possible role of WRKY70 factor in the constitutive SA accumulation., Les phosphatidylinositol 4-kinases (PI4K) sont les premières enzymes qui engagent le phosphatidylinositol dans la voie des phosphoinositides. Dans le génome d'Arabidopsis thaliana, douze isoformes putatives de PI4K ont été identifiées. Huit appartiennent au type II (AtPI4Kγ1-8) et quatre appartiennent au type III (AtPI4Kα1 et α2 et AtPI4Kβ1 et β2).Pour étudier le rôle des PI4K, j'ai travaillé avec une plante double mutante défectueuse dans les deux gènes PI4Kβ. J’ai montré que le double mutant d'Arabidopsis thaliana pi4kβ1β2 présente plusieurs phénotypes racinaires: une croissance racinaire altérée, une moindre sensibilité des racines à l'IAA exogène (acide indole-3-acétique), une gravistimulation altérée et une croissance des poils. Ces changements semblaient coïncider avec un cytosquelette d'actine moins stable et une altération de la dynamique du trafic intracellulaire dans les racines pi4kβ1β2. La teneur en auxine bioactive dans les racines pi4kβ1β2 était similaire à celle des racines de type sauvage. Ces données relient donc l'activité PI4K altérée à la modification du trafic vésiculaire et de l'organisation des filaments d'actine d'une part, et à la réponse altérée de l'auxine probablement due à l'altération de l'homéostasie de l'auxine d'autre part.La deuxième partie de ma thèse portait sur l'interaction de Blumeria graminis (Bgh) avec le double mutant pi4kβ1β2. On sait qu'Arabidopsis a une résistance non hôte à Bgh. Papilles - qui agit comme une barrière entre les champignons et les cellules végétales. Le double mutant pi4kβ1β2 a montré une meilleure pénétration de Bgh 24 hpi, donc une moindre résistance de la plante. La mutation sid2 touche le gène ISOCHORISMATE SYNTHASE 1nécessaire à la synthèse d’acide salicylique (SA). Un défaut similaire de résistance à la pénétration a été observé dans sid2/pi4kβ1β2, indiquant le caractère indépendant de SA de ce phénomène. La carence en PI4Kbetas a entraîné une diminution de l'accumulation du niveau de PI4P dans les papilles. Au cours de l'attaque pathogène, il a été démontré que de nombreux phospholipides et protéines s'accumulent dans les papilles. Mon hypothèse était que les PI4K sont essentielles pour une défense réussie des plantes contre la Bgh, et plus spécifiquement pour la formation d'une papille efficace.La troisième partie de ma thèse concerne le mécanisme conduisant à une immunité constitutivement active chez le double mutant pi4kβ1β2. Chez les plantes pi4kβ1β2 âgées de 4 semaines, une accumulation de SA. Cette accumulation de SA s'est avérée responsable de la stature naine des plantes pi4kβ1β2 âgées de 4 semaines. La question est donc de comprendre pourquoi le système immunitaire est constitutivement enclenché. Le système immunitaire pourrait être activé par l'intermédiaire de récepteurs localisés dans la membrane cellulaire ou solubles. Pour étudier le rôle des PI4K de type β dans la régulation des mécanismes de défense, j'ai d'abord croisé le double mutant pi4kβ1β2 avec plusieurs mutants affectés dans différents récepteurs ou régulateurs de l'immunité. Comme témoin, j'ai utilisé le triple mutant sid2/pi4kβ1β2 qui n'accumule pas de SA, contrairement aux plantes pi4kβ1β2. Pour le phénotype décrivant la taille de la rosette a été mesurée. Après cela, les caractéristiques typiques de l'immunité ont été testées : niveau de résistance à l'hémibiotrophe Pseudomonas syringae pv tomato DC3000, expression de PR1 et niveau d'accumulation de callose. Si l'un de ces récepteurs/régulateurs est en amont de l'accumulation de SA, j'espérais obtenir un phénotype végétal inversé avec des caractéristiques de type sauvage. Le phénotype nain pi4kβ1β2 a été préservé pour tous les mutants sauf un - wrky70/pi4kβ1β2_ ce qui indique un rôle possible du facteur de transcription WRKY70 dans l'accumulation constitutive de SA.

The complexity of food webs and how it depends on environmental variables is a long-standing question in ecology. Food-chain length depends on many factors, such as productive space, disturbance and spatial processes. It is not clear though how food-chain length should vary with adaptive evolutionary changes of the constitutive species. Assuming that each trophic level is subject to a competition-colonization trade-off, we model the adaptive evolution of their colonization rates and its consequences on equilibrium occupancies and food-chain length. When colonization rates are allowed to evolve, longer food chains can persist. Extinction, perturbation and habitat loss all affect the evolutionary-stable colonization rates, but trade-off strength (costs of dispersal) has a major role: weaker trade-offs yield longer chains. Our results suggest a strong link between within-trophic level competition, spatial occupancies and food-chain length. Although these eco-evo dynamics partly alleviate the constraint on food-chain length in metacommunities, we show it is no magic bullet: the highest, most vulnerable, trophic levels are also those that least benefit from evolution. Our model generates qualitative predictions regarding how trait evolution affects the response of communities to disturbance and habitat loss. This highlights the importance of eco-evolutionary dynamics at metacommunity level in determining food-chain length.

Thermo-hydroregulation strategies involve concurrent changes in functional traits related to energy, water balance and thermoregulation and play a key role in determining life-history traits and population demography of terrestrial ectotherms. Local thermal and hydric conditions should be important drivers of the geographical variation of thermo-hydroregulation strategies, but we lack studies that examine these changes across climatic gradients in different habitat types. Here, we investigated intraspecific variation of morphology and thermo-hydroregulation traits in the widespread European common lizard (Zootoca vivipara louislantzi) across a multidimensional environmental gradient involving independent variation in air temperature and rainfall and differences in habitat features (access to free-standing water and forest cover). We sampled adult males for morphology, resting metabolic rate, total and cutaneous evaporative water loss and thermal preferences in 15 populations from the rear to the leading edge of the distribution across an elevational gradient ranging from sea level to 1750 m. Besides a decrease in adult body size with increasing environmental temperatures, we found little effect of thermal conditions on thermo-hydroregulation strategies. In particular, relict lowland populations from the warm rear edge showed no specific ecophysiological adaptations. Instead, body mass, body condition and resting metabolic rate were positively associated with a rainfall gradient, while forest cover and water access in the habitat throughout the season also influenced cutaneous evaporative water loss. Our study emphasizes the importance of rainfall and habitat features rather than thermal conditions for geographical variation in lizard morphology and physiology.

Présentation du dispositif Observatoire de l'environnement nocturne (CNRS) et Observatoire de l'environnement nocturne de La Réunion (CNRS/Parc national de La Réunion) aux services internes du Parc national de La Réunion.

International audience; La connaissance de la biodiversité des organismes dans les milieux urbains est un enjeu majeur pour la compréhension de la résilience de nos écosystèmes en ville. Aujourd’hui, le développement de trames qui visent à maintenir et à reconstituer un réseau d’échanges d’espèces terrestres, aquatiques et nocturnes (vertes, bleues ou noires) contribue à la protection de cette diversité, notamment en améliorant les espaces dits naturels, mais aussi en offrant des continuités écologiques indispensables pour le maintien et la stabilité des communautés d’organismes.

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International audience; Within the framework of a Franco-Lebanese mission in the area of Tyre (Lebanon), we were able to improve our knowledge of the relative sea level variations on its maritime facade. Two fish tanks were discovered near the southern and northern capes of the ancient rocky island of Tyre. Both fish tanks were cut into a Pleistocene sandstone bedrock. Small water inflow and outflow channels, also cut into the sandstone bedrock, help to better understand and constrain the variations in relative sea level during ancient times in this area. The first results show that these Roman fish tanks were affected by a relative sea-level rise of ca. 0.50 m. This 0.50 m rise is usually observed around the Circum-Mediterranean since the Roman period. In other words, no tectonic movement appears to have affected this area since Roman times.

International audience; The biology and ecology of benthic fauna from extreme environments, such as the hadal zone (> 6,000 m depth), is scarce due to the difficulties of access, exploration, and work logistics. The few exploration cruises of bottom settings have shown that benthic foraminifera, and meiofauna in general, display high abundances in the sediments, indicating that these organisms present unique adaptations and interactions to extreme conditions (e. g. high hydrostatic pressure, limitation of calcite and organic matter, etc.). As such, new species to science have also been reported. The Peru-Chile trench represents the deepest ecosystem in the South Pacific. It has been explored only on three occasions describing it as a eutrophic environment with high biomass of meiofauna. For foraminifera, only species reports have been published, being the ecology neglected. In this study, we aimed to determine the community structure (abundance, diversity, spatial and vertical distribution) of the foraminifera collected from 6 stations in the Atacama trench in the SONNE Cruise during 2018. We compared the taxa features to granulometry and proxies of food, organic matter source, and oxygenation. Dissolved oxygen at all trench stations penetrated 3-5 cm into the sediments and TOC was 0.5-1.3 %. The grain size was mainly silt-rich. The presence of 120 morphospecies, many of them soft-walled, is reported. The community was dominated by large specimens (>500 µm), and small specimens (63-150 µm) were rare. The bulk of the community concentrated in the first centimeter of sediment despite all the trench stations were fully oxygenated. However, different assemblages were found in the 6 analyzed stations. We argue if these community differences are generated by the gradient of organic matter nature or the presence/abundance of meiofaunal/macrofaunal predators. Our results contribute to the knowledge of ecology and diversity of foraminifera from the Atacama Trench and give insight to the role of this group in the benthic food webs in hadal settings.

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International audience; An emerging research axis of the STEEP team (steep.inria.fr) of Inria (Grenoble, France) intends to contribute to the design, evaluation and debate of socio-technical alternatives for the future (e.g., horizon 2050). “Expert” quantitative modeling makes it possible to guarantee the biophysical coherence of narratives (regarding flows of materials, energy and human work) and to tackle complex issues (e.g. trade-offs between social and environmental criteria, trade-offs between geographical scales…) (Giampietro et al, 2021 ; Courtonne, 2016). In order for these alternatives to emerge in a democratic manner, the team is currently involved in both “expert modeling” and “participatory modeling” (where groups of citizens identify what they wish to model and create and evaluate their own alternatives). This communication will focus on the latest developments on the “expert” side.We define a socio-technical alternative as a consistent arrangement of modes of production and modes of consumption. This includes biophysical and socio-political dimensions, but for the time being the emphasis is laid on the circulation of material, energy and human work between sectors and down to final consumption.

International audience

This paper introduces an approach for land cover pixel-based classification from massive satellite image time series scale using Gaussian Processes. Sparse methods combined with variational inference allow the learning of large scale Gaussian Process. Using a spatiospectro-temporal covariance function can help to take into account all the structure of the data. Experimental results conducted on a national scale data-set show that our method is effective and close to several state-of-the-art approaches (random forest and deep learning methods)., Cet article présente une approche permettant la classification pixellaire de séries temporelles d'images satellites massives à partir de processus gaussiens. Notre modèle s'appuie sur des processus gaussiens variationnels parcimonieux associés à des fonctions de covariance spatio-spectro-temporelles. Les résultats expérimentaux réalisés sur un jeu de données à l'échelle nationale montrent que notre méthode est efficace et comparable à des approches de l'état de l'art (forêt d'arbres décisionnels et méthodes d'apprentissage profond).

International audience

International audience; Human papillomaviruses (HPVs), the most oncogenic virus known to humans, are often associated with Herpes Simplex Virus-2 (HSV-2) infections. The involvement of the latter in cervical cancer is controversial but its longterm infections might modulate the mucosal microenvironment in a way that favors carcinogenesis. We know little about coinfections between HSV-2 and HPVs, and studying the immunological and microbiological dynamics in the early stages of these infections may help identify or rule out potential interactions. We report two cases of concomitant productive, although asymptomatic, HSV-2 and HPV infections in young women (aged 20 and 25). The women were followed up for approximately a year, with clinical visits every two months and weekly self-samples. We performed quantitative analyses of their HSV-2 and HPV viral loads, immunological responses (IgG and IgM antibodies and local cytokines expression profiles), vaginal microbiota composition, as well as demographic and behavior data. We detect interactions between virus loads, immune response, and the vaginal microbiota, which improve our understanding of HSV-2 and HPVs' coinfections and calls for further investigation with larger cohorts.

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International audience; Designing agroforestry systems is a complex task due to the numerous elements and their multiple interactions. Co-design workshops are useful to overcome these difficulties by gathering people from different disciplines. But these workshops use tools that do not provide a standardised representation of agroforestry systems nor the provision of ecosystem services. Our objective is thus to develop a conceptual information framework based on graphs that allows modeling the agroforestry system and its ecosystem functions. In the first step, we infer a topological graph from the position of the physical objects representing system components: trees, crops, tree lines, and their spatial relationships (e.g. adjacency, inclusion...). We represent then the relationship between ecosystem structure and functioning as a graph. Applying graph technics such as subgraph research, we can estimate whether a specific system (graph) can support a specific ecosystem function (subgraph). This results in a new graph-based model to describe both the spatial and functional relationships between elements of agroforestry systems. Figure 1 illustrates the different steps to apply this model to a simple agroforestry system: 1. Create a system mock-up with physical objects 2. Acquire the scene by a camera and identify physical objects 3. Automatically extract the topological graph 4. Perform subgraphs research to identify functions 5. Visualize the scene with both realistic trees and schematic representations of ecosystem functions In the future, this work will be combined with augmented reality to visualize the agroforestry system and the production of ecosystem services directly on the physical mock-up. Thus, our work will improve the efficiency of co-design workshop by (i) formalizing the knowledge on the relationship between structure and function in agroforestry systems and, by (ii) sharing this information with non-specialists in a visual way, while allowing intuitive interaction through the physical mock-up. Thus, the designed system answers farmer's needs better.

One of the missions of Unesco’s intergovernmental scientific programme, Man and the Biosphere (MAB),is to support and encourage research activities. These activities are based in specific areas, the BiosphereReserves considered as model sites for the study and demonstration of integrated approaches toconservation and development. However, identifying scientific activities in Biosphere Reserves turned outto be more challenging than previously imagined. After reflecting upon the place of science at Unesco, theoriginality of the conceptualisation of this place within the MAB programme and the structural conditions of its implementation, we present different methods to identify the diversity of scientific activities withinFrench Biosphere Reserves. In a context of evolution and territorialisation of public action, this exploratorysurvey proposes a methodology allowing to come to grips with the complexity of scientific contributionswithin territorial projects whose aims are not purely academic., Le programme scientifique intergouvernemental Man and the Biosphere (MAB) de l’Unesco, dont l’une des missions est de soutenir et d’encourager les activités de recherche, s’appuie sur des territoires particuliers, les réserves de biosphère, définies comme des sites modèles d’étude et de démonstration des approches intégrées de la conservation et du développement. Pourtant, identifier les activités scientifiques dans ces réserves de biosphère se révèle bien plus complexe qu’il n’y paraît. Après avoir questionné la place de la science à l’Unesco, l’originalité de sa conceptualisation au sein du programme MAB et ses conditions structurelles de mise en œuvre, nous expérimentons et discutons,chemin faisant, différentes méthodes afin d’identifier la diversité des activités scientifiques au sein des réserves de biosphère françaises. Dans un contexte d’évolution et de territorialisation de l’action publique, cette enquête exploratoire propose in fine une méthodologie à même d’appréhender la complexité des contributions scientifiques au sein de projets de territoire dont les finalités ne sont pas purement académiques.

International audience

Morphological adjustment of small urban rivers is rarely studied especially in France. We propose an original hydrogeomorphological approach based on a detailed study of a whole catchment using field data acquired systematically all along the river: (i) channel cross-sections; (ii) riffle-pool sequences and(iii) obstacles to flow and stormwater discharges. Nine hydromorphological variables were used as a basis to classify the profiles (CAH/ACP). The classes were compared with 12 anthropogenic constraint variables to explain longitudinal morphological variability and to link morphology to pressures on this scale. The results showed an average incision of 0.50 m, an average widening of nearly 1 m, and heterogeneous distribution of the riffle-pool sequences (although not complete disappearance). Systematic analysis of within-channel forms revealed high morphological diversity, the absence of a linear relationship between the rate of urbanisation and incision/erosion, and the absence of longitudinal changes in response to urbanisation. The constraints identified are commonly observed in urbanised basins, but the variety of responses to the constraints makes it difficult to understand the system as a whole and prevents ecological restoration’s uniformity., L’ajustement morphologique des rivières urbaines est encore peu étudié. Cette étude propose une approche hydrogéomorphologique originale basée sur l’acquisition systématique et exhaustive de données de terrain sur le linéaire fluvial telles : (i) les sections transversales du chenal, (ii) lesalternances radier-mouille et (iii) les ouvrages transversaux et rejets d’eaux pluviales. Neuf de ces variables ont permis la classification des profils (CAH/ACP) en 5 classes hydromorphologiques. Cellesci ont été confrontées à douze variables de contrainte anthropiques afin d’expliquer la variabilité morphologique longitudinale et le lien entre les formes et les pressions. Les résultats montrent une incision moyenne d’environ 0,50 m, un élargissement moyen proche de 1 m, et une répartition hétérogène des séquences radiers-mouilles mais pas leur disparition. L’analyse systématique des formes intra-chenal a révélé une forte diversité morphologique, l’absence de relation linéaire entre taux d’urbanisation et incision/érosion, et l’absence d’évolution longitudinale d’un faciès « réponse àl’urbanisation ». Les contraintes identifiées sont communes aux bassins urbanisés, toutefois la diversité des réponses à ces contraintes complique l’appréhension de l’ensemble du système et s’oppose à l’uniformité de la restauration écologique.

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We analyzed 324,734 SARS-CoV-2 variant screening tests from France enriched with 16,973 whole-genome sequences sampled during September 1, 2021-February 28, 2022. Results showed the estimated growth advantage of the Omicron variant over the Delta variant to be 105% (95% CI 96%-114%) and that of the BA.2 lineage over the BA.1 lineage to be 49% (95% CI 44%-52%). Quantitative PCR cycle threshold values were consistent with an increased ability of Omicron to generate breakthrough infections. Epidemiologic modeling shows that, in spite of its decreased virulence, the Omicron variant can generate important critical COVID-19 activity in hospitals in France. The magnitude of the BA.2 wave in hospitals depends on the level of relaxing of control measures but remains lower than that of BA.1 in median scenarios.

International audience; The life of aquatic fauna in streams and rivers depends on hydrological variability with considerable emphasis on minimum discharge in flow regulated reaches. One of the methods used to define ecologically suitable minimum discharges is the physical habitat simulation method (habitat model) which converts the outputs of a hydrodynamic river model into habitat suitability for different aquatic taxa, based on their estimated hydraulic preferences. The application of this method requires the use of dedicated software. One of the current computer programs for habitat simulations in France (EVHA) is not technically up-to-date and had to be replaced. Much more than an update of existing software, HABBY is a new free and open-source program, which will be very useful to estimate ecological flows through aquatic habitat availability and suitability. Compatible with MS-Windows, macOS, and GNU/Linux, HABBY is developed in Python. It does not contain any internal hydrodynamic model but accepts, as inputs, the output files of several commonly used models. It also incorporates three statistical habitat models, including Estimhab, a popular statistical model in France. Moreover, a system of scripts helps to store past studies and facilitates the implementation of complex case studies.

International audience; Isothiazolinones are ubiquitous in our daily life; they are used as preservatives in cosmetics, household products and in building materials. These biocidal substances may be emitted inside house, inducing a potential risk for health, and released into the environment through wastewater or runoff, thus inducing a potential impact on aquatic ecosystems. The overall objective of this communication was to explore the isothiazolinone contamination of the continuum House-Sewer-River and to assess the induced risks for health and the aquatic life. The experimental results showed the ubiquity of isothiazolinones in indoor dust, urban water discharges and in the Seine River. Annual mass loads discharged into the Seine River were estimated using Monte Carlo method at both the conurbation and annual scales, they showed that wastewater discharges constitute the major entry pathway.

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