Abstract
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.
Highlights
IntroductionHuman population isolates are of particular interest for population geneticists for two reasons
There are two ways of looking at the results obtained with our resampling approach which may help us distinguish between likely signatures of genetic isolation and results biased by small sample size: (i) comparing the distribution of each single genetic statistic separately (HD, Fst, Fu’s failure of the statistic (FS)) using empirical and simulated values: (ii) making inferences regarding genetic isolation in each candidate population taking into account all three statistics together
Our first concern has been to make sure that the procedure used to build our reference neutral populations did not produce values of genetic diversity statistics that were substantially different from what observed across populations
Summary
IntroductionHuman population isolates are of particular interest for population geneticists for two reasons. Genetic isolation in humans may be associated with differences in language, religion and ethnicity (e.g. see Rosenberg et al, 2002; Bosch et al, 2006; Capocasa et al, 2013), which gives the opportunity to study the influence of cultural factors on the genetic structure of populations (Laland et al, 2010). 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. 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. Conclusion: Our analysis revealed that the use of population genetic statistics combined with resampling procedure can help detect signatures of genetic isolation in human populations even using a single, highly informative, locus like mtDNA
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