Socio-hydrogeological survey and assessment of organic pollutants to highlight and trace back pollution fluxes threatening a coastal groundwater-dependent ecosystem.

Despite being a vector of pollution towards connected ecosystems, groundwater is often underestimated or not taken into account in management frameworks. To fill this gap, we propose to add socio-economic data to hydrogeological investigations to identify past and present pollution sources linked to human activities at watershed scale in order to forecast threats towards groundwater-dependent ecosystems (GDEs). The aim of this paper is to demonstrate, by a cross-disciplinary approach, the added value of socio-hydrogeological investigations to tackle anthropogenic pollution fluxes towards a GDE and to contribute to more sustainable management of groundwater resources. A survey combining chemical compounds analysis, data compilation, land use analysis and field investigations with a questionnaire was carried out on the Biguglia lagoon plain (France). Results show a pollution with a two-fold source, both agricultural and domestic, in all water bodies of the plain. The pesticide analysis reveals the presence of 10 molecules, including domestic compounds, with concentrations exceeding European groundwater quality standards for individual pesticides, as well as pesticides already banned for twenty years. On the basis of both the field survey and the questionnaire, agricultural pollution has been identified as very local highlighting the storage capacity of the aquifer, whereas domestic pollution is diffuse over the plain and attributed to sewage network effluents and septic tanks. Domestic compounds present shorter residence time within the aquifer highlighting continuous inputs, related to consumption habits of the population. Under the Water Framework Directive (WFD), member states are required to preserve the good ecological status, quality and quantity of water bodies. However, for GDEs it is difficult to achieve the 'good status' required without considering the groundwater's pollutant storage capacity and pollution legacy. To help resolve this issue, socio-hydrogeology has proved to be an efficient tool as well as for implementing effective protection measures for Mediterranean GDEs.

Exploring disease perception in Behçet's syndrome: combining a quantitative and a qualitative study based on a narrative medicine approach.

BACKGROUND: Behçet Syndrome (BS) has a significant psychological and social impact on patients, caregivers and families. The present study aims at exploring disease perception in BS patients, using both a co-designed survey and the narrative medicine (NM) approach. METHODS: An ad-hoc questionnaire was co-designed by clinicians expert in BS, BS patients and caregivers and BS adult patients were invited to answer the online questionnaires. Cluster analysis was used to analyse data from the survey and to identify groups of patients with diverse disease perception. To further explore real-life perspectives, the stories of illness of a smaller group of adult BS patients were anonymously collected online and analysed by means of text, sentiment and qualitative analysis. RESULTS: Two hundred and seven patients answered the survey and forty-three stories were collected. The cluster analysis highlighted that accepting or not the disease has a strong impact on the daily life, on how BS patients perceive themselves and in terms of hope for the future. The stories revealed that patients often address common issues, such as the long and complex journey faced from the disease onset until the BS diagnosis, which was strongly connected to the concept of time and perceived as an exhausting period of their lives. CONCLUSION: To our knowledge, this is the first study that addressed disease perception also applying the NM principles in BS. The current perception that BS patients have of their disease should encourage the BS scientific and patient community in joining forces in order to improve the journey of BS patients.

The role of groundwater in CO2 production and carbon storage in Mediterranean peatlands: An isotope geochemistry approach.

Peatlands are permanent wetlands recognized for ecosystem services such as biodiversity conservation and carbon storage capacity. Little information is available about their response to global change, the reason why most Earth system climate models consider a linear increase in the release of greenhouse gases (GHG), such as CO2, with increasing temperatures. Nevertheless, numerous studies suggest that an increase in the temperature may not imply a decrease in photosynthesis and carbon storage rates if water availability is sufficient, the latter being under the control of local hydrology mechanisms. Mediterranean peatlands well illustrate this fact. Since they are groundwater-dependent, they are hydrologically resilient to the strong seasonality of hydroclimatic conditions, especially during the summer drought. In the present study, we demonstrate that, even if such peatlands release CO2 into the atmosphere, they can maintain a carbon storage capacity. To this end, a geochemical study disentangles the origin and fate of carbon within a Mediterranean peatland at the watershed scale. Field parameters, major ions, dissolved organic and inorganic carbon content and associated δ13C values allow for characterizing the seasonality of hydrochemical mechanisms and carbon input from an alluvial aquifer (where rain, river, shallow, and deep groundwater flows are mixing) to the peatland. The inorganic and organic content of peat soil and δ13C values of total organic matter and CO2 complete the dataset, making it possible to provide arguments in favour of lower organic matter oxidation compared to primary production. Overall, this study highlights the groundwater role in the fluxes of CO2 at the peatland-atmosphere interface, and more broadly the need to understand the interactions between the water and carbon cycles to build better models of the future evolution of the global climate.

Assessing the hydrogeological resilience of a groundwater-dependent Mediterranean peatland: Impact of global change and role of water management strategies.

Mediterranean peatlands remain largely under-documented, except for detailed biological data such as fauna and flora taxa lists, and yet are increasingly threatened by water withdrawal and agriculture practices. This lack of information, particularly on their hydrogeological functioning, makes it impossible to evaluate their response to changing climate conditions. A pilot study on a representative Mediterranean peatland on the island of Corsica (France) was conducted to evaluate recharge modalities in the peatland using a coupled water-level monitoring, geochemical and isotope multi-tracing approach (electric conductivity, major ions, δ18O, δ2H, 3H, 87Sr/86Sr). The goal was to understand how water budgets in peatland ecosystems were maintained throughout the year, especially during the summer. Despite the remarkable stability of the peatland water level, the recharge contributions of varied water bodies through an alluvial aquifer vary significantly from one season to another. An end-member mixing analysis (EMMA) indicates that the peatland is mainly recharged by an alluvial aquifer. During fall-winter, the alluvial aquifer on which the peatland depends is recharged by the rainfall, a river, and shallow groundwater (colluvium). During spring-summer, water supply is provided mostly by a river, shallow, and deep groundwater (fractured granite). However, this specific hydrogeological functioning is not taken into account by environmental management policies making peatlands vulnerable to anthropogenic and climatic pressures. Thus, their actual status regarding water and aquatic environment management policies is discussed to provide recommendations for better consideration and preservation.

Temporal offset between precipitation and water uptake of Mediterranean pine trees varies with elevation and season.

For climate models that use paleo-environment data to predict future climate change, tree-ring isotope variations are one important archive for the reconstruction of paleo-hydrological conditions. Due to the rather complicated pathway of water, starting from precipitation until its uptake by trees and the final incorporation of its components into tree-ring cellulose, a closer inspection of seasonal variations of tree water uptake is important. In this study, branch and needle samples of two pine species (Pinus pinaster and Pinus nigra subsp. laricio) and several water compartments (precipitation, creek, soil) were sampled over a two-year period and analyzed for the temporal variations of their oxygen and hydrogen stable isotope ratios (δ18O and δ2H) at five sites over an elevation gradient from sea level to around 1600 m a.s.l. on the Mediterranean island of Corsica (France). A new model was established to disentangle temporal relationships of source water uptake of trees. It uses a calculation method that incorporates the two processes mostly expected to affect source water composition: mixing of waters and evaporation. The model results showed that the temporal offset from precipitation to water uptake is not constant and varies with elevation and season. Overall, seasonal source water origin was shown to be dominated by precipitation from autumn and spring. While autumn precipitation was a more important water source for trees growing at mid- (~800-1000 m a.s.l) and high-elevation (~1600 m a.s.l.) sites, trees at coastal sites mostly took up water from late winter and spring. These findings show that predicted decreases in precipitation amounts during the wet season in the Mediterranean can have strong impacts on water availability for pine trees, especially at higher elevations.

Early diagnosis of anastomotic leakage after colorectal surgery by the Dutch leakage score, serum procalcitonin and serum C-reactive protein: study protocol of a prospective multicentre observational study by the Italian ColoRectal Anastomotic Leakage (iC.

BACKGROUND: Anastomotic leakage (AL) is a dreaded major complication after colorectal surgery. There is no uniform definition of anastomotic dehiscence and leak. Over the years many risk factors have been identified (distance of anastomosis from anal verge, gender, BMI, ASA score) but none of these allows an early diagnosis of AL. The DUtch LeaKage (DULK) score, C reactive protein (CRP) and procalcitonin (PCT) have been identified as early predictors for anastomotic leakage starting from postoperative day (POD) 2-3. The study was designed to prospectively evaluate AL rates after colorectal resections, in order to give a definite answer to the need for clear risk factors, and testing the diagnostic yeld of DULK score and of laboratory markers. Methods and analysis. A prospective enrollment for all patients undergoing elective colorectal surgery with anastomosis carried out from September 2017 to September 2018 in 19 Italian surgical centers. OUTCOME MEASURES: preoperative risk factors of anastomotic leakage; operative parameters; leukocyte count, serum CRP, serum PCT and DULK score assessment on POD 2 and 3. Primary endpoint is AL; secondary endpoints are minor and major complications according to Clavien-Dindo classification; morbidity and mortality rates; readmission and reoperation rates, length of postoperative hospital stay (Retrospectively registered at ClinicalTrials.gov Identifier: NCT03560180, on June 18, 2018). Ethics. The ethics committee of the "Comitato Etico Regionale delle Marche - C.E.R.M." reviewed and approved this study protocol on September 7, 2017 (protocol no. 2017-0244-AS). All the participating centers submitted the protocol and obtained authorization from the local Institutional Review Board.

Riverine carbon dioxide evasion along a high-relief watercourse derived from seasonal dynamics of the water-atmosphere gas exchange.

The high-relief catchment of the Tavignanu River (Corsica Island, France) with an elevation range from sea level to 2622 m above sea level was investigated for its riverine carbon budget and stable carbon isotopes. Major riverine dissolved inorganic carbon (DIC or TCO2) sources depended on seasons and sub-catchment lithology. In winter δ13CDIC values of -2 to -7‰ (VPDB) indicated influences of atmospheric CO2. δ13CDIC values decreased gradually to values between -9 and -12‰ in July, which indicates elevated soil CO2 contribution. An observed downstream increase in the total amount of carbon species correlated with inputs from carbonate bearing tributaries and evaporation effects in summer. Main channel partial pressure of CO2 (pCO2) was seasonally highly variable in the upper silicate catchment and the lower coastal plain, where summer values exceed up to six times atmospheric levels. During winter, the central section of the Tavignanu River was found to be undersaturated with respect to atmospheric CO2 levels. The median values for main channel pCO2 were below atmospheric levels in winter and spring and above in summer and autumn. The annual carbon flux across the air-water boundary (FCO2) along the Tavignanu River was calculated with (0.77 ±â€¯0.24) Gg C yr-1, which is about seven times higher than the riverine TCO2 transport to the sea of about 0.11 Gg C yr-1. While large sections of the river experienced year-round atmospheric CO2 uptake or equilibrium, the river as a whole was a small but continuous net source of carbon to the atmosphere. This underlines the important, but so far not well-constrained, contributions of smaller streams and rivers to the terrestrial carbon flux and the need of incorporating them into future global carbon cycle models.

Combinations of geoenvironmental data underline coastal aquifer anthropogenic nitrate legacy through groundwater vulnerability mapping methods.

Groundwater quality is strongly dependent on land use. Past and current anthropogenic activities can lead to the diffusion of contaminants in aquifers. This diffusion can threaten the resource exploitation for decades, thereby endangering the ecological health of groundwater dependent ecosystems. Thus, groundwater stakeholders need methods for long-term management which integrate groundwater vulnerability. This study was conducted on the shallow alluvial aquifer of the groundwater-dependent Biguglia lagoon on Corsica Island, France. The aquifer is exposed to anthropogenic contamination for many decades with nitrate contamination legacy linked to agricultural activities, uncontrolled urbanization and sewage leakages. In most cases, vulnerability mapping is done in the objective of comparing groundwater situation regarding an on-going contamination process. But the question is still pending for aquifers where contamination is inherited from past practices or contaminations and where anthropogenic influences have changed through time. To propose an effective and innovative method for territorial management in Mediterranean alluvial aquifers, four index-based groundwater vulnerability mapping methods were tested and compared: two intrinsic vulnerability mapping methods (DRASTIC and SINTACS) and two specific vulnerability mapping methods (Modified-DRASTIC and SI), the latter integrating land use in the accuracy of groundwater vulnerability. Novelty is coming from the comparison between vulnerability maps and their application and validation in a hydrosystem affected by nitrate legacy-type contamination. The specific vulnerability mapping methods are more likely to represent the current pressures to which groundwater are subject. Thus, specific vulnerability methods such as the SI one revealed here very relevant to assess groundwater quality and to react retrospectively. The comparison between groundwater nitrate legacy and intrinsic groundwater vulnerability methods appeared also useful to define priority protection areas in long-term territorial management planning (EU Water Framework Direction). In this sense, the SINTACS method seems to be the more appropriate in the Mediterranean and alluvial context of this study.

An Analytical Method for Assessing Recharge Using Groundwater Travel Time in Dupuit-Forchheimer Aquifers.

An analytical solution to calculate the recharge of unconfined aquifers with Dupuit-Forchheimer type flow conditions is proposed. This solution is derived from an existing closed-form analytical solution initially developed to determine groundwater travel time when the recharge of the aquifer is known. This existing solution has been modified to determine recharge when groundwater travel time is known. An illustration is given with a field case example for the Bonifacio aquifer of the island of Corsica (France), in the Mediterranean. In this aquifer, previously established differences in groundwater residence time between two water samples were determined from anthropogenic atmospheric gas (chlorofluorocarbons and sulfur hexafluoride) measurements. The time difference is entered into the new analytical solution to determine recharge. The calculations yield a value of average recharge that agrees with the results obtained by several other methods that were presented in previous studies to assess the recharge of the Bonifacio aquifer. Also presented in this study is a sensitivity analysis of the new analytical solution, to quantify the influence of different parameters that control recharge: hydraulic conductivity, effective porosity and the groundwater travel time. This study illustrates how geochemical data can be combined with physical models to measure recharge. Such an approach could be adopted in other homogeneous aquifers worldwide that satisfy Dupuit-Forchheimer type flow conditions.

Delayed nitrate dispersion within a coastal aquifer provides constraints on land-use evolution and nitrate contamination in the past.

Identifying sources of anthropogenic pollution, and assessing the fate and residence time of pollutants in aquifers is important for the management of groundwater resources, and the ecological health of groundwater dependent ecosystems. This study investigates anthropogenic contamination in the shallow alluvial aquifer of the Marana-Casinca, hydraulically connected to the Biguglia lagoon (Corsica, France). A multi-tracer approach, combining geochemical and environmental isotopic data (δ18O-H2O, δ2H-H2O, 3H, δ15N-NO3-, δ18O-NO3-, δ11B), and groundwater residence-time tracers (3H and CFCs) was carried out in 2016, and integrated with a study of land use evolution in the catchment during the last century. Groundwater NO3- concentrations, ranged between 2 mg/L and up to 30 mg/L, displaying the degradation of groundwater quality induced by anthropogenic activities (agricultural activities). Comparatively high δ15N-NO3- values (up to 19.7‰) in combination with δ11B values that were significantly lower (between 23‰ and 26‰) than the seawater background are indicative of sewage contamination. The ongoing deterioration of groundwater quality can be attributed to the uncontrolled urbanization development all over the alluvial plain, with numerous sewage leakages from the sanitation network and private sewage systems. Integration of contaminant and water-residence time data revealed a progressive accumulation of pollutants with time in the groundwater, particularly in areas with major anthropogenic pressure and slow dynamic groundwater flow. Our approach provides time-dependent insight into nitrogen pollution in the studied aquifer over the past decades, revealing a systematic change in the dominant NO3- source, from agricultural to sewage contamination. Yet, today's low groundwater quality is to large parts due to legacy pollution from land-use practices several decades ago, underlining the poor self-remediating capacity of this hydrosystem. Our results can be taken as warning that groundwater pollution that happened in the recent past, or today, may have dire impacts on the quality of groundwater-dependent ecosystems in the future.

Microbial communities in natural rubber coagula during maturation: impacts on technological properties of dry natural rubber.

AIM: To characterize microbial communities present in natural rubber (NR) coagula from Hevea brasiliensis latex during maturation and identify microbial taxa (bacteria and fungi) having an impact on dry NR properties. METHODS AND RESULTS: Microbial community dynamics in NR coagula maturated under controlled conditions were compared and related with the evolution of dry NR properties. The pyrosequencing of 16S (119 837 effective reads) and 18S (131 879 effective reads) rRNA gene regions was performed on 21 samples covering different maturation times and two aeration conditions. Results showed a relatively high bacterial richness (Chao1 estimates of 200-1000) associated with significant bacterial dynamics. Lactic acid bacteria (LAB) were dominant in the first days of maturation. Then, in aerobic conditions, development of Actinobacteria represented by the family Microbacteriaceae was associated with alkalinization of the samples and a higher sensitivity of NR to thermo-oxidation as evaluated by its plasticity retention index (PRI). In anaerobiosis, the reduced development of bacteria, mostly LAB present, was associated with improved NR properties (higher initial plasticity P0 and PRI). CONCLUSIONS: The involvement of micro-organisms in the evolution of dry NR properties during the maturation of NR coagula was confirmed. The importance of the structure and dynamics of microbial communities is specifically highlighted. SIGNIFICANCE AND IMPACT OF THE STUDY: Natural rubber is a key elastomer for the tyre industry and for a variety of other applications. The majority of raw NR is obtained by natural coagulation of H. brasiliensis latex under the activity of micro-organisms. An improved understanding of the microbial communities involved in the maturation of NR coagula may lead to an improvement in the production process of raw NR to provide a better consistency in NR quality.

Strontium isotopes as tracers of water-rocks interactions, mixing processes and residence time indicator of groundwater within the granite-carbonate coastal aquifer of Bonifacio (Corsica, France).

This study aims at identifying the water-rock interactions and mixing rates within a complex granite-carbonate coastal aquifer under high touristic pressure. Investigations have been carried out within the coastal aquifer of Bonifacio (southern Corsica, France) mainly composed of continental granitic weathering products and marine calcarenite sediments filling a granitic depression. A multi-tracer approach combining physico-chemical parameters, major ions, selected trace elements, stable isotopes of the water molecule and 87Sr/86Sr ratios measurements is undertaken for 20 groundwater samples during the low water period in November 2014. 5 rock samples of the sedimentary deposits and surrounding granites are also analysed. First, the water-rock interactions processes governing the groundwater mineralization are described in order to fix the hydrogeochemical background. Secondly, the flow conditions are refined through the quantification of inter aquifer levels mixing, and thirdly, the kinetics of water-rock interaction based on groundwater residence time from a previous study using CFCs and SF6 are quantified for the two main flow lines. A regional contrast in the groundwater recharge altitude allowed the oxygene-18 to be useful combined with the 87Sr/86Sr ratios to differentiate the groundwater origins and to compute the mixing rates, revealing the real extension of the watershed and the availability of the resource. The results also highlight a very good correlation between the groundwater residence time and the spatial evolution of 87Sr/86Sr ratios, allowing water-rock interaction kinetics to be defined empirically for the two main flow lines through the calcarenites. These results demonstrate the efficiency of strontium isotopes as tracers of water-rock interaction kinetics and by extension their relevance as a proxy of groundwater residence time, fundamental parameter documenting the long term sustainability of the hydrosystem.

The complex history of the olive tree: from Late Quaternary diversification of Mediterranean lineages to primary domestication in the northern Levant.

The location and timing of domestication of the olive tree, a key crop in Early Mediterranean societies, remain hotly debated. Here, we unravel the history of wild olives (oleasters), and then infer the primary origins of the domesticated olive. Phylogeography and Bayesian molecular dating analyses based on plastid genome profiling of 1263 oleasters and 534 cultivated genotypes reveal three main lineages of pre-Quaternary origin. Regional hotspots of plastid diversity, species distribution modelling and macrofossils support the existence of three long-term refugia; namely the Near East (including Cyprus), the Aegean area and the Strait of Gibraltar. These ancestral wild gene pools have provided the essential foundations for cultivated olive breeding. Comparison of the geographical pattern of plastid diversity between wild and cultivated olives indicates the cradle of first domestication in the northern Levant followed by dispersals across the Mediterranean basin in parallel with the expansion of civilizations and human exchanges in this part of the world.

AMaCAID: a useful tool for Accurate Marker Choice for Accession Identification and Discrimination.

AMaCAID is an R program designed to analyse multilocus genotypic patterns in large samples. It allows (i) the computation of the number and frequency of the different multilocus patterns available in a molecular data set and (ii) the analysis of discriminatory power of each combination of k markers among n available. It thus enables the identification of the minimum number of markers required to distinguish all the observed genotypes and the subset of markers that maximize the number of distinct genotypes. AMaCAID can be used with any kind of molecular markers, on data sets mixing different kinds of markers, but also on qualitative characters like morphological or taxonomic traits. AMaCAID has been built primarily to select subsets of markers for identifying accessions and monitoring their genetic stability during regeneration cycles in an ex situ genebank. It can, however, also be used to screen any kind of data set that characterizes a set of individuals or species (e.g. taxonomic or phylogenetic studies) for discrimination purposes. The size of the assayed sample has no limitation, but the program only performs computations on all combinations of markers when there are less than 25 markers. For larger number of markers/characters, it is possible to ask AMaCAID to screen a large but limited number of combinations of markers. We apply AMaCAID to three data sets involving either molecular or taxonomic data and give some results on the computing time of the program with respect to the size of the data set.

High throughput analysis of grape genetic diversity as a tool for germplasm collection management.

Using 20 SSR markers well scattered across the 19 grape chromosomes, we analyzed 4,370 accessions of the INRA grape repository at Vassal, mostly cultivars of Vitis vinifera subsp. sativa (3,727), but also accessions of V. vinifera subsp. sylvestris (80), interspecific hybrids (364), and rootstocks (199). The analysis revealed 2,836 SSR single profiles: 2,323 sativa cultivars, 72 wild individuals (sylvestris), 306 interspecific hybrids, and 135 rootstocks, corresponding to 2,739 different cultivars in all. A total of 524 alleles were detected, with a mean of 26.20 alleles per locus. For the 2,323 cultivars of V. vinifera, 338 alleles were detected with a mean of 16.9 alleles per locus. The mean genetic diversity (GDI) was 0.797 and the level of heterozygosity was 0.76, with broad variation from 0.20 to 1. Interspecific hybrids and rootstocks were more heterozygous and more diverse (GDI = 0.839 and 0.865, respectively) than V. vinifera cultivars (GDI = 0.769), Vitis vinifera subsp. sylvestris being the least divergent with GDI = 0.708. Principal coordinates analysis distinguished the four groups. Slight clonal polymorphism was detected. The limit between clonal variation and cultivar polymorphism was set at four allelic differences out of 40. SSR markers were useful as a complementary tool to traditional ampelography for cultivar identification. Finally, a set of nine SSR markers was defined that was sufficient to distinguish 99.8% of the analyzed accessions. This set is suitable for routine characterization and will be valuable for germplasm management.

Using linked markers to estimate the genetic age of a volunteer population: a theoretical and empirical approach.

Volunteers deriving from unharvested seeds of a crop can lead to persistent feral populations and participate in genetic exchanges across the agro-ecosystem, both between crop varieties and between crops and their wild relatives. A first step to understand the importance of volunteers is to characterize their capacity to reproduce autonomously for several generations. For that purpose, we constructed and evaluated a maximum-likelihood method to estimate the genetic age of a population deriving from one of the most common field crop type: an F1-hybrid variety. The method estimates the number of reproduction cycles that occurred since the cultivation of that variety. It makes use of genotypic data at a number of linked microsatellite loci pairs, thus exploiting the recombination of parental haplotypes, which is expected to occur as the population is reproducing. Estimates with moderate bias and variance were found for a broad range of parameter values in simulations, and the method revealed robust to some deviations from the assumptions of the underlying model. We propose a specific procedure to test the hypothesis of persistence, that is has a given volunteer population experienced more than one cycle of reproduction since the F1-hybrid state? The method was applied to both an experimental and a natural sunflower volunteer population and revealed promising, considering these ideal case studies. Possible further developments toward more complex natural systems are discussed.

Mating system and recombination affect molecular evolution in four Triticeae species.

Mating systems and recombination are thought to have a deep impact on the organization and evolution of genomes. Because of the decline in effective population size and the interference between linked loci, the efficacy of selection is expected to be reduced in regions with low recombination rates and in the whole genome of self-fertilizing species. At the molecular level, relaxed selection is expected to result in changes in the rate of protein evolution and the pattern of codon bias. It is increasingly recognized that recombination also affects non-selective processes such as the biased gene conversion towards GC alleles (bGC). Like selection, this kind of meiotic drive in favour of GC over AT alleles is expected to be reduced in weakly recombining regions and genomes. Here, we investigated the effect of mating system and recombination on molecular evolution in four Triticeae species: two outcrossers (Secale cereale and Aegilops speltoides) and two selfers (Triticum urartu and Triticum monococcum). We found that GC content, possibly driven by bGC, is affected by mating system and recombination as theoretically predicted. Selection efficacy, however, is only weakly affected by mating system and recombination. We investigated the possible reasons for this discrepancy. A surprising one is that, in outcrossing lineages, selection efficacy could be reduced because of high substitution rates in favour of GC alleles. Outcrossers, but not selfers, would thus suffer from a 'GC-induced' genetic load. This result sheds new light on the evolution of mating systems.

Grinding up wheat: a massive loss of nucleotide diversity since domestication.

Several demographic and selective events occurred during the domestication of wheat from the allotetraploid wild emmer (Triticum turgidum ssp. dicoccoides). Cultivated wheat has since been affected by other historical events. We analyzed nucleotide diversity at 21 loci in a sample of 101 individuals representing 4 taxa corresponding to representative steps in the recent evolution of wheat (wild, domesticated, cultivated durum, and bread wheats) to unravel the evolutionary history of cultivated wheats and to quantify its impact on genetic diversity. Sequence relationships are consistent with a single domestication event and identify 2 genetically different groups of bread wheat. The wild group is not highly polymorphic, with only 212 polymorphic sites among the 21,720 bp sequenced, and, during domestication, diversity was further reduced in cultivated forms--by 69% in bread wheat and 84% in durum wheat--with considerable differences between loci, some retaining no polymorphism at all. Coalescent simulations were performed and compared with our data to estimate the intensity of the bottlenecks associated with domestication and subsequent selection. Based on our 21-locus analysis, the average intensity of domestication bottleneck was estimated at about 3--giving a population size for the domesticated form about one third that of wild dicoccoides. The most severe bottleneck, with an intensity of about 6, occurred in the evolution of durum wheat. We investigated whether some of the genes departed from the empirical distribution of most loci, suggesting that they might have been selected during domestication or breeding. We detected a departure from the null model of demographic bottleneck for the hypothetical gene HgA. However, the atypical pattern of polymorphism at this locus might reveal selection on the linked locus Gsp1A, which may affect grain softness--an important trait for end-use quality in wheat.

Lichen biomonitoring of ammonia emission and nitrogen deposition around a pig stockfarm.

Effects of high ammonia emissions and nitrogen deposition were investigated on lichens around a pig stockfarm (ca. 7,000 animals) in central Italy. Four sites were selected along a transect at 200, 400, 1000 and 2500 m from the stockfarm, the diversity of epiphytic lichens was measured and transplanted thalli of Xanthoria parietina and Flavoparmelia caperata exposed, together with passive NH3 (diffusion tubes) samplers. Ammonia dramatically decreased from the centre of the stockfarm to the sampled sites, where it was correlated with bark pH. Total lichen diversity was not associated with either NH3 concentrations or bark pH, but the diversity of strictly nitrophytic species was highly correlated with both parameters. Physconia grisea was the best indicator species for NH3 pollution. Total N accumulated in X. parietina and F. caperata was correlated with NH3 concentrations.