1,720,985 research outputs found
Comparative study of the discriminating capacity of RAPD, AFLP and SSR markers and of their effectiveness in establishing genetic relationships in olive
No full textGenetic diversity and population structure of wild olives from the North Western Mediterranean assesed by SSR markers
No full textBackground and Aims Olive cultivars and their wild relatives (oleasters) represent two botanical varieties of Olea
europaea subsp. europaea (respectively europaea and sylvestris). Olive cultivars have undergone human selection
and their area of diffusion overlaps that of oleasters. Populations of genuine wild olives seem restricted to isolated
areas of Mediterranean forests, while most other wild-looking forms of olive may include feral forms that escaped
cultivation.
Methods The genetic structure of wild and cultivated olive tree populations was evaluated by amplified fragment
length polymorphism (AFLP) markers at a microscale level in one continental and two insular Italian regions.
Key Results The observed patterns of genetic variation were able to distinguish wild from cultivated populations
and continental from insular regions. Island oleasters were highly similar to each other and were clearly distinguishable
from those of continental regions. Ancient cultivated material from one island clustered with the wild plants,
while the old plants from the continental region clustered with the cultivated group.
Conclusions On the basis of these results, we can assume that olive trees have undergone a different selection/
domestication process in the insular and mainland regions. The degree of differentiation between oleasters and
cultivated trees on the islands suggests that all cultivars have been introduced into these regions from the outside,
while the Umbrian cultivars have originated either by selection from local oleasters or by direct introduction from
other regions
Genetic and morphological data reveal new insights into the taxonomy of Campanula versicolor s.l. (Campanulaceae)
No full textCampanula versicolor is a constituent of the Campanula pyramidalis complex, distributed in the central and southern Balkan Peninsula with a small disjunct range in SE Italy. The taxonomy of the broadly defined C. versicolor was controversial in the past due to high morphological variability of the populations across the range. We used microsatellite DNA data along with morphometric analyses on an extensive population sampling covering the entire range to reconstruct the relationships among populations of the intricate C. versicolor s.l. Based on the results three distinct entities can be distinguished, circumscribed here on the subspecies level, with newly established combinations: C. versicolor subsp. versicolor, C. versicolor subsp. korabensis and C. versicolor subsp. tenorei. We propose a new taxonomic treatment of C. versicolor s.l. with description, distribution and habitat data for each of the subspecies and a key for their identification
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Phylogeographic structure of common sage (Salvia officinalis L.) reveals microrefugia throughout the Balkans and colonizations of the Apennines
Get PDFStudying the population-genetic and phylogeographic structures of a representative species of a particular geographical region can not only provide us with information regarding its evolutionary history, but also improve our understanding of the evolutionary processes underlying the patterns of species diversity in that area. By analysing eight highly polymorphic microsatellite loci and two chloroplast DNA regions, we have investigated the influence of Pleistocene climate fluctuations on the evolutionary history of Salvia officinalis L. (common sage). The populations with the highest genetic diversity were located in the central parts of the Balkan distribution range. A large group of closely related haplotypes was distributed throughout the Balkans and the central Apennines, while the private lineage occupied the southern Apennines. In addition, two highly differentiated lineages were scattered only over the Balkans. The results suggest that a single refugium of the studied species from the last glacial period was located in the central part of the range in the Balkans. Numerous microrefugia, probably spanning several glaciation cycles, were scattered across the Balkans, while colonisation of the Apennines from the Balkans occurred at least on two occasions
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
