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Landscape discontinuities influence the population structure of Acer opalus ssp. obtusatum Waldst. & Kit. ex Willdenow
No full textThe major goal of landscape genetics is to understand how landscape structure genetic variation in natural populations. We
investigated molecular diversity in Acer opalus subsp. obtusatum sampled from 95 sites using 14 nuclear microsatellite loci.
The average number of alleles per nuclear microsatellite locus differed among sampling sites; the number was high (4.9
alleles) in populations from the Basilicata and Molise regions, where heterozygosity was also high (0.679, Molise; 0.669,
Basilicata). Differentiation between sites was often low (mean FST 1⁄4 0.220), indicating few genetic differences between
most sites. There was a clear excess of homozygotes (mean Ho 1⁄4 0.450, mean He 1⁄4 0.513) and a relatively high FIS
(mean 1⁄4 0.451), suggesting a consistent level of inbreeding in many A. opalus subsp. obtusatum populations. There was a
significant pattern of isolation by distance across the study area (Mantel test; R 2 1⁄4 0.0662, P , 0.001). Two assignment
methods (Structure and Geneland) produced some similarities in their definitions of population structure, especially for
populations from the Campania and Tuscany regions. These two important genetic discontinuities were not associated with
any physical barrier
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Corologia e tipificazione di Lonicera stabiana Guss. ex Pasquale (Caprifoliaceae), endemismo puntiforme della Penisola Sorrentina.
No full textEffects of fragmentation phenomena on the genetic structure and gene flow in Centaurea cineraria group (Asteraceae) in the Mediterranean Basin
No full textThe complex history of the Mediterranean region illustrates how ancient and recent phenomena are closely associated with
species distribution and the creation of phylogeographic divisions within Mediterranean flora. A good model to explore the
genetic consequences of fragmentation can be found in Centaurea cineraria and its close relatives.We applied simple sequence
repeat molecular markers to a dense population sampling throughout the distribution area of all C. cineraria taxa to study how
fragmentation has altered the genetic structure and distribution of C. cineraria. The average gene diversity (He) was 0.286,
and the average allelic richness (Ar) was 3.65 and ranged from 2.15 (C. gymnocarpa) to 5.25 (C. busambarensis). The FIS
averaged a relatively high 0.223, ranging from 20.724 in C. aeolica subsp. aeolica to 0.589 in C. leucadea. Our results indicate
that habitat fragmentation over several generations reduced heterozygosity due to random genetic drift in populations of C.
cineraria. This heterozygosity erosion becomes more severe when the inbreeding coefficient is positive and the outcrossing
rates show a significant increase. The results observed for outcrossing rates and inbreeding coefficient could also indirectly
support the possibility of disrupted gene flow or mating pattern changes in fragmented C. cineraria population
Corologia e tipificazione di Lonicera stabiana Guss. ex Pasquale (Caprifoliaceae), endemismo puntiforme della Penisola Sorrentina.
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