Genetic differentiation among and within natural and planted Cupressus sempervirens L. eastern Mediterranean populations

The aim of the study was to extend our knowledge of the geographic patterns of genetic variation of Cupressus sempervirens L., and to try to relate the earliest plantations of C. sempervirens in Israel to its ultimate seed origins. Seeds of 22 populations, most of them of C. sempervirens var. horizontalis, were used for the analysis of the genetic diversity within and among East Mediterranean populations. Bulk seed lots from 13 populations, and single-tree seed collections, representing about 30 trees from each of the populations from Cyprus, Syria and Turkey, and from 267 trees from 20 Israeli plantations were available. Horizontal starch gel electrophoresis was used to resolve allele patterns in 22 loci encoding 13 enzyme systems. The mean number of alleles per locus was 1.7; the over all percentage of polymorphic loci was 41.7% (S.E.+/-1.1). The over all mean observed heterozygosity and the expected heterozygosity, i.e., genetic diversity within populations - were 0.149 (S.E.+/- 0.021) and 0.181 (S.E.+/-0.03), respectively; and the over all mean total genetic diversity among the natural populations was 0.192 (S.E.+/-0.032). The fixation indices, F-it, F-is F-st and G(st) for each polymorphic locus, over all the populations, are 0.180, 0.333, 0.187 and 0.049, respectively. The phylogenetic tree enabled us to define three main groups: a north-eastern Mediterranean group which includes the populations from central Mediterranean Turkey, Syria and Iran; a low-altitude east Aegean group which includes the populations of Kos, 2 Turkish population on the shores of the Aegean Sea together with populations on the island of Samos; a third group which includes populations from Crete, Cyprus, Rhodes, Jordan and plantations in Israel. The results imply that plantations of Cupressus sempervirens in Israel probably originated from seed material imported from Crete, Cyprus, Rhodes and Jordan.