Ecosystems are constantly facing numerous natural and human induced perturbations, occurring both over short time scales (e.g. extreme climate events) and long time scales (e.g. change in land use). Such perturbations often alter the dynamics of ecological communities and worsen the provision of ecosystem services to human populations. Ecological communities are key elements of the response of ecosystems to global change perturbations. To assess and mitigate ecosystem response to perturbations, we need to understand how perturbations affect the diversity of species as well as the complex interactions between them, and how these effects in turn determines ecosystem stability. However, knowledge on this issue is still largely lacking, partly because the different facets of the links between global changes, community structure and ecosystem stability have been mostly considered by disconnected ecological research pieces. The project ECOSTAB aims to bring the experimental, empirical and theoretical knowledge needed to assess and understand how different components of global changes affect community structure and ecosystem stability, in terms of both the variability of ecosystem properties over time and the resistance and resilience of ecosystem properties to extreme climate events. To achieve this ambitious objective, ECOSTAB brings together a consortium of researchers with highly complementary expertise on community ecology, food web structure, ecosystem functioning, aquatic and terrestrial ecosystems, large database analyses, ecological models and management of large experimental infrastructures, to combine: (1) A unique experimental test of the consequences of two major components of global changes (eutrophication and top predator loss) and their interaction on food web structure and stability of freshwater ecosystems at fine temporal resolution. (2) An unprecedented assessment on a large temporal and spatial scale of the effects of land use alterations and climatic variability on the trophic structure of terrestrial and aquatic communities, and on the stability of large functional groups having a commercial or patrimonial value (e.g. commercial fishes, birds, butterflies). (3) Novel models with predictions connected to the stability of natural ecosystems to understand the consequences of different components of global changes (e.g. climate variability, nutrient enrichment) on stability of ecosystem functioning in complex food webs. To our knowledge, ECOSTAB would be one of the first project to tackle the study of the consequences of multiple perturbations on different components of community and ecosystem stability (variability as well as resistance and resilience to extreme climate events). Furthermore, it would do so at very different temporal and spatial scales by exploiting the synergies between experimental, empirical and theoretical approaches. In addition to novel and important scientific results, we expect that ECOSTAB’s results would also bring important knowledge on how to manage ecosystems for conserving the structure of natural communities and to restore or improve the stability of important services such as water purification, primary or secondary productivity.

Nucleolus activity and structure are intimately linked to ribosome biogenesis and functionally connected to protein synthesis, cell growth and proliferation. The driving force for nucleolus assembly is the transcription of hundred copies of 45S ribosomal genes (rDNA) by RNA polymerase I, with subsequent processing and assembly of 45S transcripts into ribosome particles. Wider and far less understood roles of the nucleolus in chromatin activity and post-translational regulatory mechanisms have been uncovered in recent years in humans, animals, yeast and plants. The nucleolus appears to influence the expression of coding and non-coding RNAs transcribed by all nuclear RNA polymerases, including RNA Pol II and III in animals and the plant-specific RNA Pol IV and V involved in transcriptional silencing in Arabidopsis. More recently, the nucleolus has also emerged as a structural scaffold that can sequester large chromatin domains and recruit nuclear proteins involved in multiple processes such as chromatin organization and transcription, RNA processing and modification, assembly of nuclear ribo-nucleoprotein complexes or of specific nuclear bodies. Still, the molecular bases leading to nucleolar-based sequestering or protein nucleolar hijacking and their potential interconnection with nucleolar and rRNA functional dynamics await to be investigated. The proposed research program is aimed at uncovering and dissecting functional connections between nucleolar activities in response to heat and light stressful conditions over generations. Heat acting in conjunction with high light causes severe threats to crops, notably by inducing plant drought and impairing disease resistance, photosynthetic efficiency and consequently plant growth. RiboStress is aimed at identifying which proteins are retained in, or excluded from, the nucleolus in response to heat and high light conditions. It will also determine the origin and the role of nucleolar long non-coding RNAs lncRNAs and their implication in nucleolar protein detention. In a complementary approach, we will further explore how nucleolar organization and activity impact transcriptional and epigenetic variations over the genome as well as the cell physiology when plants face unfavorable environmental conditions over multiple generations. A set of preliminary data and the assortment of molecular and genetic plant resources obtained by the partners constitute a solid basis to tackle the proposed objectives in assessing the impact of nucleolar structural changes and activity during stressful conditions. The combination of genetic, epigenetic and genomic resources that will benefit the different tasks is unique to the A. thaliana model species. The proposal will also benefit from large research infrastructures to perform large-scale qualitative and quantitative proteomic analyses (IR ProFI) and transgenerational studies in a perfectly controlled environment (IR ANAEE-FR ECOTRON Ile-De-France). The research program is expected to gain novel insights into how the genome sequence, epigenetic mechanisms and lncRNAs influence the structure and activity of the nucleolus. It is more generally intended to participate significantly to the intense efforts currently devoted to decipher how nuclear organization contributes to regulatory pathways and is tuned during adaptive responses of multicellular organisms to external cues, a field to which plants have much to offer. Improving the knowledge on such fundamental mechanisms is essential to understand how natural mutations affecting nucleolar function or ribosome biogenesis trigger a broad range of diseases in human (ribosomopathies, cancer, degenerative disorders) and impair plant stress response capacity.

The terrestrial vegetation releases a large variety of volatile organic compounds that constitute complex olfactory environments (odorscapes). These volatile plant compounds (VPC) play major roles as infochemicals mediating the interactions between organisms. Insects for instance extract from their odorscapes cues essential for their reproduction. Mate or host-plant finding behaviors are largely based on the perception of specific odor signals by their sensory system. There is conclusive evidence that the specialized receptors that detect the behavior-relevant odorants are sensitive to odor background. With the growing likelihood of a rapidly changing environment due to the anthropogenic emissions of greenhouse gases, the composition of future odorscapes in agro-ecosystems will largely depend on the sensitivity of VPC production to single or combined component(s) of global climatic change. Yet, the impacts of such predicable profound changes in odorscapes on insect olfaction have not been properly evaluated. Our project aims at: 1) evaluating qualitatively and quantitatively the effects of major environmental change components on metabolic pathways and emission of VPCs by crop and companion plants in two ecosystems representative of dry and humid temperate agro-ecosystems; 2) analyzing the effects of the altered odorscapes on olfaction of herbivorous insects at gene, neural coding and behavior levels. We will analyze the volatile emissions from plants associated in mini ecosystems typical for two different climatic conditions present in France: a dry temperate climate (DT) and a humid temperate climate (HT). Each mini ecosystem will consist of a cultivated plant (corn), a tree (poplar for HT or oak for DT) and a weed which will be grown in controlled conditions under CO2, ozone, drought and temperature levels representative of global change. The effects of growing conditions on the main metabolic pathways involved in the production of VPCs will be analysed. We expect that the volatile emissions from DT and HT under elevated global change factors will affect female choices for oviposition sites and male responses to sex pheromone. Thus, we will identify the natural emissions in two growing conditions, measure the response of insects and design behaviourally effective modified odorscapes HTO and DTO. The effects of HTO and DTO and their major components on olfactory coding within the antennae and the primary olfactory centres, the antennal lobes, will be investigated. The ability of insects to adapt their behaviour to changes in their sensory environment will be evaluated by investigating behavioural plasticity. The effects of long-term exposure to reconstituted odorscapes on the expression of olfactory genes within the antennae will then be tested. Our project will lead to a deeper understanding of the vulnerability of information exchanges inside agro-ecosystems to environmental changes, of the adaptive capacities of plants and insects to global changes and of their potential consequences for the functioning of agro-ecosystems. The expected results will contribute to a better predictability of the evolution of agro-ecosystems under anthropogenic influence and will also have an impact on applied aspects, taking into account that pheromones and plant odorants are used as alternative control measures for insecticides.

At the current warming rate, many organisms should go extinct if they are not able to disperse or adapt locally, which often involves plastic responses. In ectotherms, warming influences plastic life history traits with an acceleration of early life production at the expense of longevity and senescence. This may be due to trade-offs involving warming-induced oxidative stress and telomere shortening. Although pace-of-life acceleration may provide short-term benefits, it also increases sensitivity to limited resources, extreme climate events and unusual nighttime thermal conditions. Thus, in an increasingly warmer climate, ectotherms could reach critical physiological thresholds that would precipitate their decline. To date, physiological mechanisms and ecological consequences of this pace-of-life acceleration are poorly characterized. Here, we will combine experimental, observational and analytical approaches to unlock critical gaps in our understanding of thermal plasticity of life history. We will focus on a bimodal reproductive lizard (Zootoca vivipara), which offers a unique context to analyze how evolutionary transition between oviparity and viviparity influenced pace-of-life acceleration. Using long-term data sets and surveys across climatic gradients, we will document patterns of pace-of-life acceleration in response to climate warming in the two reproductive modes, focusing on vulnerable populations of the warm margin. In addition, we will perform outdoor and laboratory experiments to identify physiological tipping points in the context of day-night asymmetry of warming and extreme climate events. Given their major potential role in this thermal plasticity, non-energetic trade-offs will be quantified using longitudinal and cross-sectional assays of oxidative stress and telomere length dynamics. Altogether, this project will highlight patterns, mechanisms, and consequences on population viability of pace-of-life acceleration in response to climate warming.

Cyanobacteria blooms frequently disturb the functioning of freshwater ecosystems and their uses, due to the toxins dangerous to health that cyanobacteria are able to synthesize. Therefore, many countries have implemented monitoring programs aimed at reducing the risk of human exposure to these toxins. The main limitation is related to the heterogeneity of the spatial distribution of cyanobacteria. In the vertical dimension, these organisms can stay in different layers in the water column and in the horizontal scale, the cells may accumulate in some area of the water body, under the action of winds or currents. In an attempt to improve monitoring, many research projects have been undertaken in order to develop new tools, like buoys developed during the program PROLIPHYC (ANR PRECODD). This tool is highly relevant but it does not allow assessing the horizontal distribution of cyanobacteria and its cost remains expensive. In addition, if satellite remote sensing can be considered very useful for estimating biomass and horizontal distribution of cyanobacteria in a water body, the cost of this technology and the lack of satellite availability make it unaffordable for routine monitoring. In this context, our OSS-CYANO project aims to develop and validate a new, low-cost aerial sensor, to be used in a fixed single location, or deployed in network, to detect the presence of cyanobacteria in a water body. In addition, OSS-CYANO also aims to implement a drone capable of carrying the sensor to perform spatial measurements on large water bodies or river sections, and other instruments for water sampling or for performing underwater measurements. Our project is organized into five tasks. Task 1 is dedicated to (i) the coordination of the project, (ii) the scientific animation and dialogue with end-users through the formation of a monitoring committee and (iii) dissemination of results, including the organization at the end of the project of an international workshop dedicated to new monitoring tools. The second task will help to identify potential end-users and identify their expectations for the developed tools. Task 3, a key task of the project, will involve technical development of the sensor (wavelength selection, influence of natural processes on the measurements ...) and of the drone system (implementation of an adaptive platform for supporting the measuring equipments). These developments will largely benefit on the facilities offered by the support center PLANAQUA (French label "Investissement d’avenir ") which provides all the required facilities to carry out tests of the sensor on a range of aquatic systems, from microcosm to macrocosm. The fourth task will test in real conditions of application, and in the long term, the sensor and the drone on different lakes and river systems impacted by representative cyanobacteria. Finally, the last task will relate to (i) data processing methodologies and data integration, (ii) the implementation of a three-dimensional hydrodynamic model using data from the sensor and / or drone to forecast short-term changes of the spatial dispersion of cyanobacteria in a water body, and (iii) to define the characteristics of a future warning system. This project relies on the participation of six laboratories and a private company. All these teams have the required skills for all planned work and have already collaborated on previous research projects.