Browsing by Author "Szmidt, A.E."
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- Comparison of genetic diversity estimates within and among populations of maritime pine using chloroplast simple-sequence repeat and amplified fragmentPublication . Ribeiro, M.M.A.; Mariette, Stéphanie; Vendramin, Giovanni Giuseppe; Szmidt, A.E.; Plomion, Christophe; Kremer, AntoineWe compared the genetic variation of Pinus pinaster populations using amplified fragment length polymorphism (AFLP) and chloroplast simple-sequence repeat (cpSSR) loci. Populations’ levels of diversity within groups were found to be similar with AFLPs, but not with cpSSRs. The high interlocus variance associated with the AFLP loci could account for the lack of differences in the former. Although AFLPs revealed much lower genetic diversity than cpSSRs, the levels of among-population differentiation found with the two types of marker were similar, provided that loci showing fewer than four null-homozygotes, in any population, were pruned from the AFLP data. Moreover, the French and Portuguese populations were clearly differentiated from each other, with both markers. The Mantel test showed that the genetic distance matrix calculated using the AFLP data was correlated with the matrix derived from the cpSSRs. Because of the concordance found between markers we conclude that gene flow was indeed the predominant force shaping nuclear and chloroplastic genetic variation of the populations within regions, at the geographical scale studied.
- Taxonomic position and origin of the endemic Sicilian fir Abies nebrodensis (Lojac.) Mattei based on allozyme analysisPublication . Parducci, L.; Szmidt, A.E.; Ribeiro, M.M.A.; Drouzas, A.D.Abies nebrodensis (Lojac.) Mattei (Sicilian fir) is a forest tree species endemic to the mountainous regions of northern Sicily (the Madonie Range) that is currently represented by just one population of 29 individuals. The major questions relating to this species are its unknown origin and its uncertain taxonomic position. According to many authors A. nebrodensis is morphologically intermediate between the neighboring Mediterranean Abies species: Abies alba (Mill.) (silver fir), Abies numidica (De Lann) (Algerian fir) and Abies cephalonica (Loud) (Greek fir). In the present study we analyzed eight enzyme systems in the population of A. nebrodensis and in seven populations from A. alba, A. cephalonica and A. numidica. The aim was to clarify the taxonomic position and origin of A. nebrodensis. High values of expected heterozygosity and number of polymorphic loci were found in A. cephalonica, while A. alba and A. nebrodensis showed intermediate levels of polymorphism and A. numidica was the least variable species. All values were similar to those found in other conifers. The relatively high level of diversity found in A. nebrodensis confirms that despite the extremely small population size, the few individuals left in this species still retain a considerable amount of the original genetic variation at the nuclear level. Results also showed that all the species were differentiated from each other, although A. nebrodensis showed a closer affinity to A. alba and in particular to the population from southern Italy. Our results, together with results from previous studies provide support for the classification of A. nebrodensis as a separate taxon and suggest that this species may have originated through a past hybridization event.