Search results for "POPULATIONS"
showing 10 items of 493 documents
Energetically costly precopulatory mate guarding in the amphipod Gammarus pulex: causes and consequences
2003
Precopulatory mate guarding (PCMG) is thought to have evolved as a male mating strategy in species in which female receptivity is limited to a short time. It is common among crustaceans, and energetic costs associated with PCMG are thought to promote size-assortative pairing in such species, although direct evidence is lacking. Using both field surveys and laboratory experiments, we assessed the energetic costs of PCMG in Gammarus pulex and investigated their possible causes. Energetic costs were measured as differences in lipid and glycogen reserves. In field-collected samples, size-corrected lipid and glycogen reserves of paired males were both significantly higher than those of unpaired …
Algorithms for {K, s+1}-potent matrix constructions
2013
In this paper, we deal with {K, s + 1}-potent matrices. These matrices generalize all the following classes of matrices: k-potent matrices, periodic matrices, idempotent matrices, involutory matrices, centrosymmetric matrices, mirrorsymmetric matrices, circulant matrices, among others. Several applications of these classes of matrices can be found in the literature. We develop algorithms in order to compute {K, s + 1}-potent matrices and {K, s + 1}-potent linear combinations of {K, s + 1}-potent matrices. In addition, some examples are presented in order to show the numerical performance of the method. (C) 2012 Elsevier B.V. All rights reserved.
Simulation of the relative atomic populations of elements 1 ≤ Z ≤89 following charge exchange tested with collinear resonance ionization spectroscopy…
2019
© 2019 The Authors Calculations of the neutralisation cross-section and relative population of atomic states were performed for ions beams (1 ≤ Z ≤ 89) at 5 and 40 keV incident on free sodium and potassium atoms. To test the validity of the calculations, the population distribution of indium ions incident on a vapour of sodium was measured at an intermediate energy of 20 keV. The relative populations of the 5s 2 5p 2 P 1/2 and 5s 2 5p 2 P 3/2 states in indium were measured using collinear resonance ionization spectroscopy and found to be consistent with the calculations. Charge exchange contributions to high-resolution lineshapes were also investigated and found to be reproduced by the calc…
Calculating minimum discrepancy to assess the nestedness of species assemblages
2009
Nestedness is a pattern whereby species-poor assemblages are composed of subsets of the species occurring in richer assemblages. One of the most commonly used measures of the degree of nestedness for presence-absence matrices is the ‘discrepancy’ metric. A hitherto neglected property of that metric is that it may take several values for a given site-by-species matrix in the presence of ties in the marginal totals. This complicates the quantification of nestedness for the observed presence-absence matrix, as well as the assessment of statistical significance, which is typically achieved through Monte Carlo simulations. A solution to the problem is to calculate the minimum discrepancy using a…
Phylogeography and demographic inference in Nacella (Patinigera) concinna (Strebel, 1908) in the western Antarctic Peninsula
2011
10 pages; International audience; Endemic to Antarctic ecosystems, the limpet Nacella (Patinigera) concinna (Strebel, 1908) is an abundant and dominant marine benthic invertebrate of the intertidal and shallow subtidal zone. In order to examine the phylogeographic pattern and historical demography of the species along the western Antarctic Peninsula, we amplified 663 bp of the mitochondrial DNA cytochrome oxidase subunit I of 161 N. concinna specimens from five localities, as well as two specimens from South Georgia and Sub-Antarctic Marion Island. As two different morphotypes, one characterized by an elevated shell in the intertidal and the other by a flat one in the subtidal, have been re…
Environmental Metal Pollution Considered as Noise: Effects on the Spatial Distribution of Benthic Foraminifera in two Coastal Marine Areas of Sicily …
2008
We analyze the spatial distributions of two groups of benthic foraminifera (Adelosina spp. + Quinqueloculina spp. and Elphidium spp.), along Sicilian coast, and their correlation with six different heavy metals, responsible for the pollution. Samples were collected inside the Gulf of Palermo, which has a high level of pollution due to heavy metals, and along the coast of Lampedusa island (Sicily Channel, Southern Mediterranean), which is characterized by unpolluted sea waters. Because of the environmental pollution we find: (i) an anticorrelated spatial behaviour between the two groups of benthic foraminifera analyzed; (ii) an anticorrelated (correlated) spatial behaviour between the first …
Finding the missing link between diversity and activity using denitrifying bacteria as a model functional community
2005
The recent development and application of numerous methods mainly based on 16S rDNA analyses have brought insights into the questions of which and how many bacterial populations can be found in a given ecosystem. A new and challenging question for microbial ecologists has emerged from the exploration of this diversity: what is its significance for ecosystem functioning? We propose the denitrifying bacteria as a model microbial community for understanding the relationship between community structure and activity, and have summarized the recent progress in studies of this functional community.
Origin and phylogeography of the Chagas disease main vector Triatoma infestans based on nuclear rDNA sequences and genome size
2004
For about half of all Chagas disease cases T. infestans has been the responsible vector. Contributing to its genetic knowledge will increase Our understanding of the capacity of geographic expansion and domiciliation of triatomines. Populations of all infestans subcomplex species, T. infestans, T. delpontei, T. platensis and T. melanosoma and the so-called T. infestans "dark morph", from many South American countries were studied. A total of 10 and 7 different ITS-2 and ITS-1 haplotypes, respectively, were found. The total intraspecific ITS-2 nucleotide variability detected in T. infestans is the highest hitherto known in triatomines. ITS-1 minisatellites, detected for the first time in tri…
Characterisation of Lymnaea cubensis, L. viatrix and L. neotropica n. sp., the main vectors of Fasciola hepatica in Latin America, by analysis of the…
2007
Although, in the endemic areas throughout the world, human fascioliasis presents varying patterns in its epidemiology, the species of lymnaeid snail that act as intermediate hosts and vectors are always crucial in the transmission of the causative parasites. Species in the Galba/Fossaria group of snails, such as Lymnaea cubensis, L. viatrix var. A ventricosa, L. viatrix var. B elongata and Galba truncatula, appear to be frequently involved in the transmission of Fasciola hepatica in Central and South America, although specific classification within this morphologically and anatomically confusing group is often very difficult. To explore the potential use of molecular analyses in the identif…
"Table 14" of "Search for magnetic monopoles and stable high-electric-charge objects in 13 TeV proton-proton collisions with the ATLAS detector"
2019
Selection efficiency as a function of transverse kinetic energy $E^\text{kin}_\text{T}=E_\text{kin}\sin\theta$ and pseudorapidity $|\eta|$ for $g=2g_\textrm{D}$ monopoles of mass 500 GeV.