Mitochondrial control-region sequence variation in the Corsican population, France

The mtDNA sequence variation of the hypervariable segment I of the control region was studied in 47 unrelated individuals of Corsican origin from Cort e (Corsica, France). Thirty-one different sequences were identified by 40 v ariable sites, of which five involve transversions. The nucleotide diversit y among the sequences was estimated as 1.03%. The pairwise difference agree d with the model proposed by Rogers and Harpending ([1992] Mol Biol Evol 9: 552-569) and appeared bell-shaped, with only one peak at 3.71, indicating t he occurrence of a single episode of demographic expansion roughly 14,443 t o 41,584 years ago. From our results it seems that the ancestral Corsican p opulation expanded more recently than all other studied European population s. Compared to other populations by genetic distances and a neighbor-joinin g tree, Corsicans appear most closely linked to the Basques and Sardinians than to other populations. Although the results substantiate an east-to-wes t migration, some problems are evident: 1) the estimates of demographic exp ansion are not in agreement with paleontological data; 2) the expansion occ urred later than the expansion of the Sardinian population; and 3) the gene tic affinity between Corsicans, Basques, and Sardinians. Answers will need to come from archaeological, paleontological, genetic, geological, and clim atological observations. Finally, the study of mtDNA confirms what had alre ady been shown with classic genetic markers. (C) 2000 Wiley-Liss, Inc.