275 research outputs found
Trophic specializations of damselfishes are tightly associated with reef habitats and social behaviours
peer reviewedDespite the increasing need to understand factors shaping community assembly, few studies have simultaneously explored the influence of niche-based and phylogenetic processes. Here, we investigate the relationships between diet, habitat and social behaviour in damselfishes (Pomacentridae) collected in 2014 at Moorea Island (17°30′S, 149°50′W), French Polynesia. Isotope ratios of carbon and nitrogen, in association with stomach contents, delineate three trophic groups: pelagic feeders consuming zooplankton, benthic feeders mainly grazing on algae and an intermediate group feeding on prey from the whole bentho-pelagic compartment. Sulphur isotope ratios indicate segregation between species of the outer reef mostly depending on oceanic input of zooplankton and the lagoonal species relying on locally produced resources or even on terrestrial supply. We demonstrate a tight association between dietary specializations, habitat characteristics and social behaviours, and these correlations are further confirmed by integrating the phylogeny of Pomacentridae. We also provide evidence of phylogenetic conservatism for the stomach content and the habitat–behaviour characters. However, the isotopic trait is evolutionarily more labile probably because it thoroughly depicts the ecological niche of species. To summarize, pelagic feeders (mainly from the Chrominae) usually form shoals in areas close to the open ocean at a maximum depth of 20 m. Benthic feeders (well represented in the Stegastinae) are ubiquitous, solitary and mostly territorial species found at various depths. The intermediate group includes gregarious species from three subfamilies that forage in the lagoon usually above 12 m depth. Overall, we give insight into processes that have structured the damselfish community in Moorea
Implementation of agronomical and geochemical modules into a 3D groundwater code for assessing nitrate storage and transport through unconfined Chalk aquifer
International audienceChalk aquifer is the main water resource for domestic water supply in many parts in northern France. In same basin, groundwater is frequently affected by quality problems concerning nitrates. Often close to or above the drinking water standards, nitrate concentration in groundwater is mainly due to historical agriculture practices, combined with leakage and aquifer recharge through the vadose zone. The complexity of processes occurring into such an environment leads to take into account a lot of knowledge on agronomy, geochemistry and hydrogeology in order to understand, model and predict the spatiotemporal evolution of nitrate content and provide a decision support tool for the water producers and stakeholders. To succeed in this challenge, conceptual and numerical models representing accurately the Chalk aquifer specificity need to be developed. A multidisciplinary approach is developed to simulate storage and transport from the ground surface until groundwater. This involves a new agronomic module " NITRATE " (NItrogen TRansfer for Arable soil to groundwaTEr), a soil-crop model allowing to calculate nitrogen mass balance in arable soil, and the " PHREEQC " numerical code for geochemical calculations, both coupled with the 3D transient groundwater numerical code " MARTHE ". Otherwise, new development achieved on MARTHE code allows the use of dual porosity and permeability calculations needed in the fissured Chalk aquifer context. This method concerning the integration of existing multidisciplinary tools is a real challenge to reduce the number of parameters by selecting the relevant equations and simplifying the equations without altering the signal. The robustness and the validity of these numerical developments are tested step by step with several simulations constrained by climate forcing, land use and nitrogen inputs over several decades. In the first time, simulations are performed in a 1D vertical unsaturated soil column for representing experimental nitrates vertical soil profiles (0-30m depth experimental measurements in Somme region). In the second time, this approach is used to simulate with a 3D model a drinking water catchment area in order to compared nitrate contents time series calculated and measured in the domestic water pumping well since 1995 (field in northern France – Avre Basin region). This numerical tool will help the decision-making in all activities in relation with water uses
Exoplanet phase curves: observations and theory
Phase curves are the best technique to probe the three dimensional structure
of exoplanets' atmospheres. In this chapter we first review current exoplanets
phase curve observations and the particular challenges they face. We then
describe the different physical mechanisms shaping the atmospheric phase curves
of highly irradiated tidally locked exoplanets. Finally, we discuss the
potential for future missions to further advance our understanding of these new
worlds.Comment: Fig.5 has been updated. Table 1 and corresponding figures have been
updated with new values for WASP-103b and WASP-18b. Contains a table
sumarizing phase curve observation
Causes and consequences of dispersal in biodiverse spatially structured systems: what is old and what is new?
Dispersal is a well recognized driver of ecological and evolutionary
dynamics, and simultaneously an evolving trait. Dispersal evolution has
traditionally been studied in single-species metapopulations so that it remains
unclear how dispersal evolves in spatially structured communities and food
webs. Since most natural systems are biodiverse and spatially structured, and
thus affected by dispersal and its evolution, this knowledge gap should be
bridged.
Here we discuss whether knowledge established in single-species systems holds
in spatially structured multispecies systems and highlight generally valid and
fundamental principles. Most biotic interactions form the ecological theatre
for the evolutionary dispersal play because interactions mediate patterns of
fitness expectations in space and time. While this allows for a simple
transposition of certain known drivers to a multispecies context, other drivers
may require more complex transpositions, or might not be transferred. We
discuss an important quantitative modulator of dispersal evolution in the
increased trait dimensionality of biodiverse meta-systems and an additional
driver in co-dispersal.
We speculate that scale and selection pressure mismatches due to
co-dispersal, together with increased trait dimensionality may lead to slower
and more "diffuse" evolution in biodiverse meta-systems. Open questions and
potential consequences in both ecological and evolutionary terms call for more
investigation
A New Analysis of 8 Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b
With over 30 phase curves observed during the warm Spitzer mission, the
complete data set provides a wealth of information relating to trends and
three-dimensional properties of hot Jupiter atmospheres. In this work we
present a comparative study of seven new Spitzer phase curves for four planets
with equilibrium temperatures of T 1300K: Qatar-2b, WASP-52b,
WASP-34b, and WASP-140b, as well as the reanalysis of the 4.5 \micron
Qatar-1b phase curve due to the similar equilibrium temperature. In total, five
4.5 \micron phase curves and three 3.6 \micron phase curves are analyzed
here with a uniform approach. Using these new results, in combination with
literature values for the entire population of published Spitzer phase curves
of hot Jupiters, we present evidence for a linear trend of increasing hot spot
offset with increasing orbital period, as well as observational evidence for
two classes of planets in apparent redistribution vs. equilibrium temperature
parameter space, and tentative evidence for a dependence of hot spot offset on
planetary surface gravity in our 1300 K sample. We do not find trends in
apparent heat redistribution with orbital period or gravity. Non-uniformity in
literature Spitzer data analysis techniques precludes a definitive
determination of the sources or lack of trends.Comment: 22 pages, 13 figures, 6 tables. Accepted for publication in AAS
journal
Ongoing Laboratory Performance Study on Chemical Analysis of Hydrophobic and Hydrophilic Compounds in Three Aquatic Passive Samplers
The quality of chemical analysis is an important aspect of passive sampling-based environmental assessments. The present study reports on a proficiency testing program for the chemical analysis of hydrophobic organic compounds in silicone and low-density polyethylene (LDPE) passive samplers and hydrophilic compounds in polar organic chemical integrative samplers. The median between-laboratory coefficients of variation (CVs) of hydrophobic compound concentrations in the polymer phase were 33% (silicone) and 38% (LDPE), similar to the CVs obtained in four earlier rounds of this program. The median CV over all rounds was 32%. Much higher variabilities were observed for hydrophilic compound concentrations in the sorbent: 50% for the untransformed data and a factor of 1.6 after log transformation. Limiting the data to the best performing laboratories did not result in less variability. Data quality for hydrophilic compounds was only weakly related to the use of structurally identical internal standards and was unrelated to the choice of extraction solvent and extraction time. Standard deviations of the aqueous concentration estimates for hydrophobic compound sampling by the best performing laboratories were 0.21 log units for silicone and 0.27 log units for LDPE (factors of 1.6 to 1.9). The implications are that proficiency testing programs may give more realistic estimates of uncertainties in chemical analysis than within-laboratory quality control programs and that these high uncertainties should be taken into account in environmental assessments
Lymphopenia combined with low TCR diversity (divpenia) predicts poor overall survival in metastatic breast cancer patients
Lymphopenia (< 1Giga/L) detected before initiation of chemotherapy is a predictive factor for death in metastatic solid tumors. Combinatorial T cell repertoire (TCR) diversity was investigated and tested either alone or in combination with lymphopenia as a prognostic factor at diagnosis for overall survival (OS) in metastatic breast cancer (MBC) patients. The combinatorial TCR diversity was measured by semi quantitative multi-N-plex PCR on blood samples before the initiation of the first line chemotherapy in a development (n = 66) and validation (n = 67) MBC patient cohorts. A prognostic score, combining lymphocyte count and TCR diversity was evaluated. Univariate and multivariate analyses of prognostic factors for OS were performed in both cohorts. Lymphopenia and severe restriction of TCR diversity called “divpenia” (diversity ≤ 33%) were independently associated with shorter OS. Lympho-divpenia combining lymphopenia and severe divpenia accurately identified patients with poor OS in both cohorts (7.6 and 10.6 vs 24.5 and 22.9 mo). In multivariate analysis including other prognostic clinical factors, lympho-divpenia was found to be an independent prognostic factor in the pooled cohort (p = 0.005) along with lack of HER2 and hormonal receptors expression (p = 0.011) and anemia (p = 0.009). Lympho-divpenia is a novel prognostic factor that will be used to improve quality of MBC patients’ medical care
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