We calculated Tajima’s D over the regions of the nicotinic receptors on chromosomes 8 and 15, as well as lactase on chromosome 2 as the positive control. As the program utilized does not incorporate ancestral information, all results are based on the folded frequency spectrum, i.e. the distribution of polymorphic sites according to the number of chromosomes that carry a given minor allele rather than the number of chromosomes that carry the derived, non-ancestral allele. [26]Fig 1 shows regional plots of the Tajima’s D values for the LCT, CHRNA5-A3-B4 nicotinic receptor gene region and the CHRNA6-B3 gene region. Within each of these regions, we calculated sliding windows of 10 kb with an increment of 1 kb. We then compared the number of windows within each region with Tajima’s D values above 2 or below -2 (this represents the 95% confidence interval of values in our data) to permutations of 10,000 randomly selected regions of the same size across the genome.
