Chloroplast DNA variation of white oaks in Italy

Polymorphisms in non-coding regions of the chloroplast genome was studied in four white oak species (Q. robur, Q. Petraea, Q. pubescens, and Q. frainetto) in Italy (aminland and associated islands, including Corsica). A total of 924 trees (194 populations) was analysed. This data set also includes results previously obtained on 20 Italina and Corsican populations. most of the sampled individuals were classified as Q. pubecsens (73.5%). Thirty-four populations out of 194 (17.5%) were polymorphic. The levl of population subdivision was very high, as expressed by the value of the coefficient Gst=0.870 (hs=0.100, ht=0.776). The higest value of total genetic diversity was calculated in Sardinia and Central Italy; the lowest in the southern Italy. The higest level of differentiation among populations occured in sardinia (Gst=1), and in Corsica (Gst=0.927). The found evidences that the Italian oak populations of today mainly originated from Sicilian and Balkan refugia. Their origin and migration routes are more easily seen by considering data separately for the four sampling regions: the north, the centre, the south and the three mian islands. The c (=blue) lineage was common in the southern part of Italy. This may be a trace of the migration from the Balkans via the Adriatic bridge duirng quaternary cold period. The northern part of the country had a set of haplotypes similar to the other Alpine regions. Most Sicilian populations are fixed for one of the two haplotypes that probably originated in the island: one spread over the whole Italian peninsula, whereas the other one did not reach the Alps. results showed that the Appennines may have played a role in the distribution of the haplotypes western and eastern of the mountain chain.