Search results for "index"
showing 10 items of 5395 documents
Identifying Early Warning Signals for the Sudden Transition from Mild to Severe Tobacco Etch Disease by Dynamical Network Biomarkers
2019
This article belongs to the Special Issue The Complexity of the Potyviral Interaction Network.
Morphological, chemical, and genetic diversity of wild myrtle(Myrtus communis L.) populations in Sicily
2016
Myrtus communis L. İs a shrub widespread in the Mediterranean area. The interest in this species is growing, mainly due to its pharmacological and aromatic properties. The overexploitation of wild populations induced increasing degradation of plant cover with serious risk of loss of genetic diversity. This research explored the morphological, chemical, and genetic diversity of wild myrtle populations in Sicily, with the aim to provide a first characterization of a core collection of 36 accessions from 7 localities for future domestication programs. Amplified fragment length polymorphism fingerprinting generated 152 polymorphic fragments. STRUCTURE analysis identified three genetic clusters …
Intensity of male-male competition predicts morph diversity in a color polymorphic lizard.
2017
Sexual selection is one of the main processes involved in the emergence and maintenance of heritable colour polymorphisms in a variety of taxa. Here we test whether the intensity of sexual selection, estimated from population sex ratio, predicts morph diversity in Podarcis muralis, a colour polymorphic lizard with discrete white, yellow, orange, white-orange, and yellow-orange male and female phenotypes (i.e. morphs). In a sample of 116 Pyrenean populations and 5421 lizards, sex ratios (m/f) vary from 0.29 to 2.5, with the number of morphs for each sex ranging from 2 to 5. Male-biased sex ratios are associated with increased morph diversity as measured with Shannon's diversity index. The ma…
Stress integrated tests and cytological analyses reveal Brassica villosa subsp. drepanensis seed quality decrease upon long-term storage
2016
Under stress integrated germination test (SIGT), seeds undergo osmo-saline stresses, which enable to detect differences in vigour of long-term stored seeds with high germination percentage (G%). The quality of Brassica villosa subsp. drepanensis seeds stored in a genebank (at -20°C for 16 years) was compared with seeds at harvest by standard germination tests (GT), SIGT and cytogenetic analysis. No differences were detected in G% and mean germination time under GT. Conversely, SIGT performed with NaCl -0.9MPa osmotic potential did not influence G% at harvest but reduced that of stored seeds, SIGT at -1.4MPa reduced G% of both. Cytogenetic analysis showed reduction of mitotic index, appearan…
Photoprotection dynamics observed at leaf level from fast temporal reflectance changes
2018
Vegetation dynamically reacts to the available photosynthetically active radiation (PAR) by adjusting the photosynthetic apparatus to either a light harvesting or a photoprotective modus. When activating the photoprotection mechanism, either minor or major pigment-protein interactions may occur at the leaf level, resulting in different light absorption and consequently reflectance intensities. The reflectance changes were measured during sudden illumination transients designed to provoke fast adaptation to high irradiance. Different spectral reflectance change features were observed during different stages of photoprotection activation, extending over part of the visible spectral range (i.e…
Energy intake functions and energy budgets of ectotherms and endotherms derived from their ontogenetic growth in body mass and timing of sexual matur…
2017
Abstract Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of sexual maturation within life, and energy intake functions. Here, we present a mathematical model applicable to ectothermic and endothermic vertebrates. It is designed to test whether differences in the timing of sexual maturation within an animal's life (age at which sexual maturity is reached vs. longevity) together with its ontogenetic gain in body mass (growth curve) can predict the energy intake throughout the animal's life (food intake curve) and can explain differences in energy partitioning (between growth, repro…
Temporal variability in detritus resource maintains diversity of bacterial communities
2008
Competition theory generally predicts that diversity is maintained by temporal environmental fluctuations. One of the many suggested mechanisms for maintaining diversity in fluctuating environments is the gleaner-opportunist trade-off, whereby gleaner species have low threshold resource levels and low maximum growth rates in high resource concentration while opportunist species show opposite characteristics. We measured the growth rates of eight heterotrophic aquatic bacteria under different concentrations of chemically complex plant detritus resource. The growth rates revealed gleaner-opportunist trade-offs. The role of environmental variability in maintaining diversity was tested in a 28-…
A unified vegetation index for quantifying the terrestrial biosphere
2021
[EN] Empirical vegetation indices derived from spectral reflectance data are widely used in remote sensing of the biosphere, as they represent robust proxies for canopy structure, leaf pigment content, and, subsequently, plant photosynthetic potential. Here, we generalize the broad family of commonly used vegetation indices by exploiting all higher-order relations between the spectral channels involved. This results in a higher sensitivity to vegetation biophysical and physiological parameters. The presented nonlinear generalization of the celebrated normalized difference vegetation index (NDVI) consistently improves accuracy in monitoring key parameters, such as leaf area index, gross prim…
Data synergy between leaf area index and clumping index Earth Observation products using photon recollision probability theory
2018
International audience; Clumping index (CI) is a measure of foliage aggregation relative to a random distribution of leaves in space. The CI can help with estimating fractions of sunlit and shaded leaves for a given leaf area index (LAI) value. Both the CI and LAI can be obtained from global Earth Observation data from sensors such as the Moderate Resolution Imaging Spectrometer (MODIS). Here, the synergy between a MODIS-based CI and a MODIS LAI product is examined using the theory of spectral invariants, also referred to as photon recollision probability ('p-theory'), along with raw LAI-2000/2200 Plant Canopy Analyzer data from 75 sites distributed across a range of plant functional types.…
Spatial Variation of Leaf Optical Properties in a Boreal Forest Is Influenced by Species and Light Environment
2017
Leaf Optical Properties (LOPs) convey information relating to temporally dynamic photosynthetic activity and biochemistry. LOPs are also sensitive to variability in anatomically related traits such as Specific Leaf Area (SLA), via the interplay of intra-leaf light scattering and absorption processes. Therefore, variability in such traits, which may demonstrate little plasticity over time, potentially disrupts remote sensing estimates of photosynthesis or biochemistry across space. To help to disentangle the various factors that contribute to the variability of LOPs, we defined baseline variation as variation in LOPs that occurs across space, but not time. Next we hypothesized that there wer…