83 research outputs found

    Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily

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    In order to empirically assess the effect of actual seed sampling strategy on genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have analysed the genetic composition of two seedling lots (nursery stock and plantation) and their known natural seed origin stand by means of six nuclear microsatellite loci. Significant reduction in genetic diversity and significant difference in genetic composition of the seedling lots compared to the seed origin stand were detected. The female and the total effective number of parents were quantified by means of maternity assignment of seedlings and temporal changes in allele frequencies. Extremely low effective maternity numbers were estimated (Nfe \approx 2-4) and estimates accounting for both seed and pollen donors gave also low values (Ne \approx 35-50). These values can be explained by an inappropriate forestry seed harvest strategy limited to a small number of spatially close trees

    Analysis of BAC end sequences in oak, a keystone forest tree species, providing insight into the composition of its genome

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    <p>Abstract</p> <p>Background</p> <p>One of the key goals of oak genomics research is to identify genes of adaptive significance. This information may help to improve the conservation of adaptive genetic variation and the management of forests to increase their health and productivity. Deep-coverage large-insert genomic libraries are a crucial tool for attaining this objective. We report herein the construction of a BAC library for <it>Quercus robur</it>, its characterization and an analysis of BAC end sequences.</p> <p>Results</p> <p>The <it>Eco</it>RI library generated consisted of 92,160 clones, 7% of which had no insert. Levels of chloroplast and mitochondrial contamination were below 3% and 1%, respectively. Mean clone insert size was estimated at 135 kb. The library represents 12 haploid genome equivalents and, the likelihood of finding a particular oak sequence of interest is greater than 99%. Genome coverage was confirmed by PCR screening of the library with 60 unique genetic loci sampled from the genetic linkage map. In total, about 20,000 high-quality BAC end sequences (BESs) were generated by sequencing 15,000 clones. Roughly 5.88% of the combined BAC end sequence length corresponded to known retroelements while <it>ab initio </it>repeat detection methods identified 41 additional repeats. Collectively, characterized and novel repeats account for roughly 8.94% of the genome. Further analysis of the BESs revealed 1,823 putative genes suggesting at least 29,340 genes in the oak genome. BESs were aligned with the genome sequences of <it>Arabidopsis thaliana</it>, <it>Vitis vinifera </it>and <it>Populus trichocarpa</it>. One putative collinear microsyntenic region encoding an alcohol acyl transferase protein was observed between oak and chromosome 2 of <it>V. vinifera.</it></p> <p>Conclusions</p> <p>This BAC library provides a new resource for genomic studies, including SSR marker development, physical mapping, comparative genomics and genome sequencing. BES analysis provided insight into the structure of the oak genome. These sequences will be used in the assembly of a future genome sequence for oak.</p

    Whole-Genome Analysis of Diversity and SNP-Major Gene Association in Peach Germplasm

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    Peach was domesticated in China more than four millennia ago and from there it spread world-wide. Since the middle of the last century, peach breeding programs have been very dynamic generating hundreds of new commercial varieties, however, in most cases such varieties derive from a limited collection of parental lines (founders). This is one reason for the observed low levels of variability of the commercial gene pool, implying that knowledge of the extent and distribution of genetic variability in peach is critical to allow the choice of adequate parents to confer enhanced productivity, adaptation and quality to improved varieties. With this aim we genotyped 1,580 peach accessions (including a few closely related Prunus species) maintained and phenotyped in five germplasm collections (four European and one Chinese) with the International Peach SNP Consortium 9K SNP peach array. The study of population structure revealed the subdivision of the panel in three main populations, one mainly made up of Occidental varieties from breeding programs (POP1OCB), one of Occidental landraces (POP2OCT) and the third of Oriental accessions (POP3OR). Analysis of linkage disequilibrium (LD) identified differential patterns of genome-wide LD blocks in each of the populations. Phenotypic data for seven monogenic traits were integrated in a genome-wide association study (GWAS). The significantly associated SNPs were always in the regions predicted by linkage analysis, forming haplotypes of markers. These diagnostic haplotypes could be used for marker-assisted selection (MAS) in modern breeding programs

    Platform specificity and the politics of location data extraction

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    The rise of smart phone use, and its convergence with mapping infrastructures and large search and social media corporations, has led to a commensurate rise in the importance of location. While locations are still defined by fixed longitude/latitude coordinates, they now increasingly &#039;acquire dynamic meaning as a consequence of the constantly changing location-based information that is attached to them&#039; becoming &#039;a near universal search string for the world&#039;s data&#039;. As the richness of this geocoded information increases, so the commercial value of this location information also increases. This article examines the growing commercial significance of location data. Informed by recent calls for &#039;medium-specific analysis&#039;, we build on earlier work to argue that social media companies actively extract location data for commercial advantage in quite specific ways. By not paying due and careful attention to the specifics of data extraction strategies, political and cultural economic analyses of new media services risk eliding key differences between new media platforms, and their respective software systems, patterns of consumer use, and individual revenue models. In response, we develop a comparative analysis of two platforms - Foursquare and Google - and examine how each extracts and uses geocoded user data. From this comparative exploration of platform specificity, we aim to draw conclusions concerning marketing (economic) surveillance, and how Foursquare&#039;s and Google&#039;s operations work in the service of fostering the securitization of mobility - the process by which the capacity to track and predict mobility and associated patterns of consumption is directly productive of value
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