Chloroplast DNA polymorphism reveals little geographical structure in Castanea sativa Mill. (Fagaceae) throughout southern European countries

The distribution of haplotypic diversity of 38 European chestnut (Castanea sativa Mill.) populations was investigated by PCR/RFLP analysis of regions of the chloroplast and mitochondrial genomes in order to shed light on the history of this heavily managed species. The rapid expansion of chestnut st arting from 3000 years ago is strongly related to human activities such as agricultural practice. This demonstrates the importance of human impact, wh ich lasted some thousands of years, on the present-day distribution of the species. No polymorphism was detected for the single mitochondrial analysed region, while a total of 11 different chloroplast (cp) haplotypes were sco red. The distribution of the cpDNA haplotypes revealed low geographical str ucture of the genetic diversity. The value of population subdivision, as me asured by G(STc), is strikingly lower than in the other species of the fami ly Fagaceae investigated. The actual distribution of haplotypic diversity m ay be explained by the strong human impact on this species, particularly du ring the Roman civilization of the continent, and to the long period of cul tivation experienced during the last thousand years.