The Strait of Gibraltar (SG) is reputed for being both a bridge and a geographic barrier to biological exchanges between Europe and Africa. Major genetic breaks associated with this strait have been identified in various taxa, but it is unknown whether these disjunctions have been produced simultaneously or by independent biogeographic processes. Here, the genetic structure of five conifers distributed on both sides of the SG was investigated using mitochondrial (nad1 b/c, nad5-1, nad5-4 and nad7-1) and chloroplast (Pt1254, Pt15169, Pt30204, Pt36480, Pt71936 and Pt87268) DNA markers. The distribution of genetic variation was partially congruent between types of markers within the same species. Across taxa, there was a significant overlapping between the SG and the genetic breaks detected, especially for the four Tertiary species surveyed (Abies pinsapo complex, Pinus nigra, Pinus pinaster and Taxus baccata). For most of these taxa, the divergence of populations across the SG could date back to long before the Pleistocene glaciations. However, their strongly different cpDNA G(ST) and R(ST) values point out that they have had dissimilar population histories, which might include contrasting amounts of pollen-driven gene flow since their initial establishment in the region. The fifth species, Pinus halepensis, was genetically depauperated and homogenous on both sides of the SG. A further analysis of nuclear DNA sequences with coalescent-based isolation with migration models suggests a Pleistocene divergence of P. halepensis populations across the SG, which is in sharp contrast with the pre-Pleistocene divergence dates obtained for P. pinaster. Altogether, these results indicate that the genetic breaks observed across this putative biogeographical barrier have been produced by independent evolutionary processes related to the biological history of each individual species instead of a common vicariant phenomenon.

Traditional Tar Production from Cedrus libani A. Rich on the Taurus Mountains in Southern Turkey. Cedrus libani A. Rich is a magnificent and sacred tree species native to the eastern Mediterranean region. Today, traditional people in southern Turkey produce wood extract, called katran, from C. libani, and use it to protect wooden structures against insects and fungi, to fight parasites and bacteria, and to heal wounds and cure various diseases in humans and domestic animals, both internally and externally. Here we illustrate traditional methods of producing katran, its use by local people, and its chemical composition.

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Turkish Red Pine (Pinus brutia Ten.) is an important forest tree species in Turkey for various economic and ecological reasons. In this study, nine RAPD (Randomly Amplified Polymorphic DNA) primers were used to determine genetic variation within and among populations of P. brutia located at the Duzlercami common-garden test site. This site was established in 1979 and includes six natural populations of P. brutia from two altitudinal transects extending from the coast to higher elevations in the Antalya region of Turkey. A total of 32 polymorphic RAPD loci were found in the analyzed six populations. The mean proportion of polymorphic loci among population samples equals 100%, mean number of alleles for each locus = 2.0, effective allele number = 1.71, Shannon's information index = 0.58, and mean Nei (1973)'s gene diversity value = 0.4. According to G ST results, a high proportion of genetic diversity (95-99%) is found within populations. A relatively high genetic differentiation was found among altitudinal population pairs in both transect. Also, data on quantitative traits (total height and/or diameter) at different ages (13, 17, 30 years) were compared with molecular data. There are similarities between the results obtained from RAPD markers and those obtained from the quantitative traits. The differentiation in quantitative traits appears to be due to local adaptation of populations. Data suggest that priority should be given to the selection of material based on geographic origin along the altitudinal gradients of P. brutia populations to conserve the genetic resource of species.

IntroductionTaxonomic classification of the genus Abies in the Mediterranean Basin has been difficult to define due to various reasons, such as hybridization among certain species, wide geographical range, diverse ecological habitats, and great genetic variability within and/or among species (