Phenotypic plasticity and gene diversity in Pistacia lentiscus L. along environmental gradients in Israel

The Mediterranean common shrub Pistacia lentiscus is distributed in a wide range of habitats along the climatic gradient in Israel. We studied the factors that may shape its morphological, physiological, and genetic differentiation. We examined the phenotypic and molecular genetic variability among and within the six Israeli populations as correlated with the local environmental conditions. The genetic structure of the shrub on the island of Cyprus was also examined. Plant morphological parameters correlated significantly with the local environmental conditions, especially with the annual precipitation and temperature. Gene diversity did not differ significantly among locations, and, hence, no differentiation among Israeli populations or between populations in Israel and Cyprus was found. The major part of the molecular variance (69%) was found within the populations, 22% of the variance was found between Israel and Cyprus and 9% among the populations within the region. Gene flow estimates among all the tested populations were high with no indication for the isolation by distance. We did not find any pattern of ecologically related genetic differentiation; hence, the morphological and physiological differences are probably due to phenotypic plasticity. It seems that the ability of P. lentiscus to express the different phenotypes in response to the varying conditions in the Mediterranean region is an adaptive trait in a species that is characterized by intensive gene flow.