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Background: A number of studies which have investigated isolation patterns in human populations rely on the analysis of intra- and inter-population genetic statistics of mtDNA polymorphisms. However, this approach makes it difficult to differentiate between the effects of long-term genetic isolation and the random fluctuations of statistics due to reduced sample size. Aim: To overcome the confounding effect of sample size when detecting signatures of genetic isolation. Subjects and methods: A re-sampling based procedure was employed to evaluate reduction in intra-population diversity, departure from surrounding genetic background and demographic stationarity in 34 Italian populations subject to isolation factors. Results: Signatures of genetic isolation were detected for all three statistics in seven populations: Pusteria valley, Sappada, Sauris, Timau settled in the eastern Italian Alps and Cappadocia, Filettino and Vallepietra settled in the Appenines. However, this study was unable to find signals for any of the statistics analysed in 19 populations. Finally, eight populations showing signals of isolation were found for one or two statistics. Conclusion: The analysis revealed that the use of population genetic statistics combined with re-sampling procedure can help detect signatures of genetic isolation in human populations, even using a single, although highly informative, locus like mtDNA. [ABSTRACT FROM AUTHOR]

Abstract: Three geographic areas of Italy have been sampled and genotyped for 9 Y chromosome STRs: DYS19, DYS385, DYS388, DYS389 I and II, DYS390, DYS391, DYS392, DYS393. Sampling was focused on residents of small areas, well distant from major urban centres. Only individuals whose grandfather would live in the same area were included. A total of 210 unrelated individuals were collected. Distribution of genetic variation across the three samples and comparison with previously published Italian database indicated that so far Y chromosome diversity has been only partially explored in the Italian Peninsula. [Copyright &y& Elsevier]

Analysis of geographic variation for eight red cell markers in Italy shows significant spatial structure for most alleles. Effective population sizes estimated from FST values at these loci are much smaller than those predicted from data on consanguineous marriage, suggesting the presence of factors (presumably barriers) that have reduced gene flow and enhanced the evolutionary weight of genetic drift. Most regions of sharp gene frequency change correspond to geographic and linguistic harriers. Two allele frequencies are significantly correlated with measures of linguistic differentiation but not with indexes describing broad religious and social attitudes. The similarity between patterns of genetic and linguistic variation in Italy, also observed in a previous study, suggests that in specific areas linguistic diversity has acted as a biological barrier constraining mating, dispersal, or both. There is no evidence for a similar role of other extant cultural barriers. [ABSTRACT FROM AUTHOR]