Genetics, History, and Ethnicity in Daghestan

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This is a proposal to (1) develop new methods for analyzing gene distributions within and between populations and relating these to population history and relationships, (2) type a large collection of DNA from different ethnic groups from Daghestan, and (3) use these genetic data to study history and relationships of the peoples of the Daghestan region. Genetic methods for studying population history have been compromised by the inability to separate effects of small population size from population genetic isolation. Two populations that separate accumulate differences at a rate proportional to time divided by population size, and the inability to know population size has required researchers to assume equal population sizes for all populations studied. This is not an acceptable assumption. The new availability of large numbers of highly diverse markers will allow the estimation of relative population effective sizes separately from genetic distances among populations, then use the effective size estimates to scale distances. The investigators will type 60 short tandem repeat markers and several hundred Alu marker loci in approximately 400 samples from Daghestan. Short tandem repeats are free from the ascertainment bias that has obscured global patterns of human diversity ascertained from classical markers and single nucleotide polymorphisms. Alu insertions enjoy the property that the ancestral state at the locus, absence of the marker, is always known. This property will be used to disentangle old from recent genetic isolation of populations..