Search results for " ECOLOGY"
showing 10 items of 2331 documents
Coopératives (agricoles)
2018
International audience; La coopération est l’une des clés de la transition écologique de l’agriculture. La raison est d’abord économique, le secteur coopératif occupant une place considérable dans le paysage agricole. Elle est ensuite philosophique, tant l’esprit qui anime le mouvement coopératif peut favoriser l’émergence d’un nouveau modèle social et environnemental de production.
L’Observatoire de l’environnement nocturne de La Réunion, un dispositif partenarial de recherche-action territorialisée
2022
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.
Functional response of species to multiscale landscape structure in a vector-borne disease
2007
International audience; The functional response of species to landscape is a recurring issue in landscape ecology. The scale levels favourable to the parasite responsible for a vector-borne disease, alveolar echinococcosis, have been explored in the Doubs department in eastern France. The method consists in maximizing landscape composition's heterogeneity in the environment of infected and non-infected georeferenced samples at various scales. The aim is to identify scale levels at which the positive samples' landscapes are the most specific and differ the most from the landscape in the environment of all samples. Three scales were identified and the distance to the positive samples' composi…
Extrapolation of the Species Accumulation Curve for Incomplete Species Samplings: A New Nonparametric Approach to Estimate the Degree of Sample Compl…
2015
9 pages; International audience; Incomplete species samplings are deemed to remain the common practice in those groups of animals, such as small or micro- invertebrates, with numerous species that often are more or less difficult to detect in the field. Thus, extrapolating the Species Accumulation Curve as far as possible beyond the actual sample size may thus serve as a useful (although imperfect) surrogate to the desired, but practically inaccessible, complete samplings. In this context, several kinds of theoretical or empirical models for the Species Accumulation Curve and also a lot of estimators of the asymptotic limit of the Curve (i.e. total species richness) have been proposed. The …
Could the acid-base status of Antarctic sea urchins indicate a better-than-expected resilience to near-future ocean acidification?
2015
13 pages; International audience; Increasing atmospheric carbon dioxide concentration alters the chemistry of the oceans towards more acidic conditions. Polar oceans are particularly affected due to their low temperature, low carbonate content and mixing patterns, for instance upwellings. Calcifying organisms are expected to be highly impacted by the decrease in the oceans' pH and carbonate ions concentration. In particular, sea urchins, members of the phylum Echinodermata, are hypothesized to be at risk due to their high-magnesium calcite skeleton. However, tolerance to ocean acidification in metazoans is first linked to acid–base regulation capacities of the extracellular fluids. No infor…
Linking species interactions with phylogenetic and functional distance in European bird assemblages at broad spatial scales
2017
Aim: Understanding the relative contribution of different species interactions in shaping community assembly has been a pivotal aim in community ecology. Biotic interactions are acknowledged to be important at local scales, although their signal is assumed to weaken over longer distances. We examine the relationship between positive, neutral and negative pairwise bird abundance distributions and the phylogenetic and functional distance between these pairs after first controlling for habitat associations. Location: France and Finland. Time period: 1984 to 2011 (Finland), 2001 to 2012 (France). Major Taxa studied: Birds. Methods: We used results from French and Finnish land bird monitoring pr…
Qanat, gebbie and water sources: the last refuge for the malacologican freshwater fauna in Palermo (Sicily, Italy)
2017
The surroundings of Palermo were characterized, over the centuries, by the presence of many natural environments of great ecological and faunal importance. These environments were placed in a context characterized by minimal and sustainable urban development and large agriculture areas, dedicated to the development of tree crops such as citrus and orchards. These crops were supported by an imposing irrigation system that, using natural resources such as watercourses, wells and springs, collected and distributed water in soils through tanks, gebbie, qanat, irrigation channels (saje), etc. Fresh water mollusks, like many other animal and vegetable organisms, spread from the natural freshwater…
Effects of density, species interactions, and environmental stochasticity on the dynamics of British bird communities
2022
Our knowledge of the factors affecting species abundances is mainly based on time-series analyses of a few well-studied species at single or few localities, but we know little about whether results from such analyses can be extrapolated to the community level. We apply a joint species distribution model to long-term time-series data on British bird communities to examine the relative contribution of intra- and interspecific density dependence at different spatial scales, as well as the influence of environmental stochasticity, to spatiotemporal interspecific variation in abundance. Intraspecific density dependence has the major structuring effect on these bird communities. In addition, envi…
The evolutionary dynamics of adaptive virginity, sex-allocation and altruistic helping in haplodiploid animals
2018
In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here, we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g., when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests ("split sex ratios"), which promotes the evolution of altruistic helping by daughters in mated queen nests. H…
Species-Specific Antioxidant Power and Bioactive Properties of the Extracts Obtained from Wild Mediterranean Calendula Spp. (Asteraceae)
2019
In this study we focused on four taxa of the genus Calendula (C. maritima, C. suffruticosa subsp. fulgida, C. arvensis, and the hybrid between the first two ones), collected in Mediterranean area (Sicily). Six extracts for each species were obtained using solvents with increasing polarity (hexane, ethanol 80%, acetone 70%, and water) and through extraction by supercritical fluids (SFE). It has been observed that the solvent with the highest extraction efficiency was ethanol 80% for all species. However, SFE extracts showed high antioxidant activity comparable to the ethanol 80% extract (polyphenol, DPPH, and reducing power method). These findings were confirmed by in vitro analysis (MTT ass…