Phylogeography and gene diversity of the gall-forming aphid Aploneura lentisci in the Mediterranean basin

Pistacia lentiscus L. (Anacardiaceae) is a common shrub in the Mediterranean vegetation. Throughout its distribution area, this species is the obligate host of the kidney-shaped gall-forming aphid Aploneura lentisci (Homoptera: Fordinae). Despite the wide distribution of Pistacia lentiscus in diverse habitats along a climatic gradient in Israel, our previous study did not reveal any pattern of ecologically related genetic differentiation. Here we examined changes in gall density and genetic diversity of the gall-forming aphid A. lentisci along its distribution gradient in Israel, in the neighboring island of Cyprus, and in Tunisia, North Africa. Gall density and mass differed significantly among the Israeli populations and were positively correlated with annual precipitation and plants' annual growth. Gene diversity of A. lentisci was very low in all populations and, as with its host plant, the genetic similarity was high within and among the Israeli populations and between the Israeli and Cyprian populations. To conclude, we found no evidence for any gene flow barrier and genetic differentiation among the aphid populations.