203 research outputs found

    Southern Italian wild boar population, hotspot of genetic diversity

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    The wild boar, Sus scrofa, is an important game species widely distributed in Eurasia. Whereas the genetic variability of most European wild boar populations is well known, the status of wild boar living in Southern Italy is not as clear. We evaluated the present and past genetic diversity (D-loop, mtDNA) of the South Italian population, comparing it with that observed in other Mediterranean glacial refugia. Italian population showed highest genetic variability, if compared to other two European refugia (Iberian and Balkan). Most of samples from Italy carried sequences belonging to the European E1 haplogroup (80.9%) with a small proportion of the private Italian E2 (10.2%) and of the Asian (8.9%) ones. Italian samples carrying an Asian haplotype were genotyped by MC1R nuclear gene, failing to disclose a recent introgression from domestic pigs. Mismatch distribution analysis of the Italian population was affected by secondary contacts between these different lin- eages. This genetic melting pot was detected since the Mesolithic and the Neolithic age, during which we found samples belonging to the indigenous Italian and European haplogroups. Further, a Near-Eastern haplotype was found in 1,800 AD samples from Southern and Central Italy. Our res- ults can be in agreement with post-glacial recolonization theories, as well as with the long history of human-mediated translocations of Sus scrofa in the Mediterranean basi

    The blue lizard spandrel and the island syndrome

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    <p>Abstract</p> <p>Background</p> <p>Many small vertebrates on islands grow larger, mature later, lay smaller clutches/litters, and are less sexually dimorphic and aggressive than their mainland relatives. This set of observations is referred to as the 'Island Syndrome'. The syndrome is linked to high population density on islands. We predicted that when population density is low and/or fluctuating insular vertebrates may evolve correlated trait shifts running opposite to the Island Syndrome, which we collectively refer to as the 'reversed island syndrome' (RIS) hypothesis. On the proximate level, we hypothesized that RIS is caused by increased activity levels in melanocortin receptors. Melanocortins are postranslational products of the proopiomelanocortin gene, which controls pleiotropically pigmentation, aggressiveness, sexual activity, and food intake in vertebrates.</p> <p>Results</p> <p>We tested the RIS hypothesis performing a number of behavioral, genetic, and ontogenetic tests on a blue colored insular variant of the Italian Wall lizard <it>Podarcis sicula</it>, living on a small island off the Southern Italian coast. The population density of this blue-colored variant was generally low and highly fluctuating from one year to the next.</p> <p>In keeping with our predictions, insular lizards were more aggressive and sexually dimorphic than their mainland relatives. Insular males had wide, peramorphic heads. The growth rate of insular females was slower than growth rates of mainland individuals of both sexes, and of insular males. Consequently, size and shape dimorphism are higher on the Island. As predicted, melanocortin receptors were much more active in individuals of the insular population. Insular lizards have a higher food intake rate than mainland individuals, which is consistent with the increased activity of melanocortin receptors. This may be adaptive in an unpredictable environment such as Licosa Island. Insular lizards of both sexes spent less time basking than their mainland relatives. We suspect this is a by-product (spandrel) of the positive selection for increased activity of melanocortins receptors.</p> <p>Conclusions</p> <p>We contend that when population density is either low or fluctuating annually as a result of environmental unpredictability, it may be advantageous to individuals to behave more aggressively, to raise their rate of food intake, and allocate more energy into reproduction.</p

    Spatial genetic structure in the Eurasian otter (Lutra lutra) meta-population from its core range in Italy

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    We characterized the genetic structure of the Eurasian otter (Lutra lutra) meta-population living in the core of its Italian distribution range providing results from 191 fresh spraints, collected from 24 watercourses included in Southern Italy. Furthermore, according to ecological corridors and barriers, we discuss the likely ways of movement and possible evolutionary fate of these populations. We genotyped 136 samples using 11 Lut microsatellite nuclear markers amplified from faecal dna. Microsatellites were moderately variable (Ho = 0.45; He = 0.46), with a total number of alleles and average number of alleles per locus in the meta-population of 50 and 4.54, respectively. No significant heterozygosity excess was observed in meta-population suggesting no recent population bottlenecks. Bayesian clustering discriminated a sub-structuring of the meta-population in five putative clusters, indicating that local populations are genetically differentiated: three of these seem to be identifiable with geographically defined sub-populations (from the Cilento, Agri and Basento river basins). The fourth is represented by multiple sub-populations with admixed genotype, that include genotypes from the Lao, Sinni and Abatemaco river basins, living in a landscape with the higher environmental permeability. Landscape genetic analysis could provide evidence of an unexpected ecological corridor: the seacoast, highlighted, for the first time as a new way for the dispersion of the South-Italian otters. Deepening the knowledge of these perspectives is crucial to identify solid strategies aimed at the future health of the populations of the Italian otters, by restoring dispersal corridors and managing the watercourses

    Operations of and Future Plans for the Pierre Auger Observatory

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    Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200

    Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory

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    Atmospheric parameters, such as pressure (P), temperature (T) and density, affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle Physic

    Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

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    Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{6×10196\times 10^{19}eV}. The anisotropy was measured by the fraction of arrival directions that are less than 3.13.1^\circ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron 12th12^{\rm th} catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (386+7)(38^{+7}_{-6})%, compared with 2121% expected for isotropic cosmic rays. This is down from the early estimate of (6913+11)(69^{+11}_{-13})%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201

    Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV

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    We describe the measurement of the depth of maximum, Xmax, of the longitudinal development of air showers induced by cosmic rays. Almost four thousand events above 10^18 eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106 +35/-21) g/cm^2/decade below 10^(18.24 +/- 0.05) eV and (24 +/- 3) g/cm^2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm^2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.Comment: Accepted for publication by PR
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