HIGH MITOCHONDRIAL SEQUENCE DIVERSITY IN LINGUISTIC ISOLATES OF THE ALPS

Segment I of the control region of mtDNA (360 bases) was sequenced in seven samples, each of 10 individuals inhabiting villages in the easte rn Italian Alps (South Tyrol and Trentino). Three linguistic groups, G erman, Italian, and Ladin, were represented by two samples each; the s eventh sample comes from an isolated group of German origin, the Moche ni, who are linguistically distinct and geographically separated from the bulk of the German speakers. Seventy-four polymorphic sites were i dentified, defining 63 different haplotypes. Mocheni and Ladin speaker s tend to form two clusters in the evolutionary trees inferred from se quences. Analysis of molecular variance shows significant differentiat ion within samples, among them, and among linguistic groups. Genetic d ifferences between the Ladins and the other groups are not much smalle r than between Europeans and some Africans; variation is large within groups, as well, with the exception of only the Mocheni. In the evolut ionary trees where the four alpine groups are compared with other Euro pean populations, Mocheni and especially Ladins appear as clear outlie rs. Romansch-speaking Swiss, who are linguistically related to Ladins, are not genetically similar to them, for this segment of DNA. Because the time elapsed since colonization of the Alps (less than or equal t o 12,000 years) is short in mutational terms, the only model accountin g for the observed relationships between mtDNA variation and linguisti c identity seems one in which a population ancestral to Ladin speakers was already differentiated long before the Alps were settled and the current linguistic affiliations were established. For the Mocheni, the results are consistent with a simpler episode of allele loss, from an original genetic pool common to the ancestors of the current German s peakers.