Genetic variation of Pinus brutia from islands of the northeastern Aegean Sea

The present study concentrated on Pinus brutia TEN. one of the main forest species of the Aegean islands and one of the most important low-elevation Mediterranean conifers. In this report the amount and structure of genetic diversity of four Pinus brutia populations which forms an integral prerequisite for breeding efforts and for the protection of the species genetic resources, is presented. One population per island was sampled from four islands of the north- eastern Aegean namely Lesvos, Chios, Samos and Thasos. Seven isoenzymic loci (Dia-1, Idh-1, Lap-1, Mdh-1, Mdh-4, Pgd-1 and Pgi-2) were identified and used for the evaluation of genetic variability in the above populations. Five of the loci studied were polymorphic, while a total of 17 alleles were detected. All populations presented significant amounts of genetic diversity and heterozygosity. The levels of genetic diversity parameters were higher than those of earlier reports regarding this species, but in agreement with values reported for conifer trees in general. Genotypic frequencies of the population samples were in agreement with those expected from HARDY- WEINBERG expectations. Results also point towards the absence of inbreeding and random genetic drift. Most of the genetic diversity of Pinus brutia (97.9%) was found within populations and only 2.1% among populations. Most of the alleles studied were common for all populations. Some differences among populations were detected for rare alleles. Populations present low values of NEI's genetic distance and CAVALLI-SFORZA and EDWARDS' chord distance. Two groups were revealed in the respective dendrograms: the first group formed by the populations of Lesvos, Chios and Samos, and the secondby the Thasos population. The significance of these results in breeding and forest management practice is briefly discussed.