GEOGRAPHIC-VARIATION IN HUMAN MITOCHONDRIAL-DNA CONTROL REGION SEQUENCE - THE POPULATION HISTORY OF TURKEY AND ITS RELATIONSHIP TO THE EUROPEAN POPULATIONS

The hypervariable segment I of the control region of the mtDNA (positi ons 16024-16383) was amplified from hair roots by PCR and sequenced in 45 unrelated individuals from Anatolia (Asian Turkey). Forty differen t sequences were found, defined by 56 variable positions, of which onl y one involves a transversion. The neighbor-joining tree of Kimura's d istance matrix for all sequences shows four main clusters. Cluster D w as found to be the most statistically robust of the four, and all the sequences in it shared a mutation that is present only in European and West Asian populations. The variability in cluster D could have origi nated between 37,000 and 107,000 years ago. No branch is unexpectedly long, denoting the absence of sequences that diverged much before the others. The pairwise difference distribution is bell-shaped, in accord ance with a population expansion occurring roughly 35,000 to 100,000 y ears ago. When compared to other Caucasoid populations through the pai rwise difference distribution, there is a pattern from the Middle East (older expansion) to the various European populations, with Turkey in an intermediate position; when Turkish sequences are compared through a neighbor-joining tree on a genetic distance matrix of populations, this position is again evidenced. Although there is a very low level o f genetic divergence among Caucasoid populations as shown by mtDNA con trol region sequences, a geographic pattern of genetic variation emerg es, denoting a stepping-stone position of Turkey between the Middle Ea st and Europe, which is in agreement with the hypothesis of a replacem ent of Neanderthals by modem humans, which could be related to the Upp er Paleolithic cultural expansion.