Observed autosomal heterozygosity (including both polymorphic and monomorphic sites) varied across all populations. Sub-Saharan African countries had the highest heterozygosity values observed (Figure 2). Asian and South American countries had the second highest heterozygosity estimates, followed by North American and European countries (Figure 2). Across all the countries, the observed heterozygosity was lower than the expected heterozygosity for all populations. Tajima’s D values for each continent ranged from -0.0001-0.0003, indicating no demographic changes within populations among continents (Figure S4).
Hierarchical population structure analysis (AMOVA) revealed significant variation partitioned at each population hierarchical level (Table 3). The variation among continents was 25%, among countries within continents was 21%, among individuals within countries was 24% and lastly the individual variation among all individuals was 29%. FST values between continents were also relatively high. The highest FST values were found between Africa vs non-African countries and Oceania vs Europe (0.441) (Table 4). Low FST values between Asia and other continents suggest that it is the least differentiated continent relative to others. We also observed the lowest FST values between geographically proximal continents (e.g.: between North and South America; between Asia and Oceania). The pairwise-FSTvalues between countries further explains the overall continental differentiation patterns in Table 4.
Table 3: Global AMOVA results as a weighted average across all polymorphic loci the SNP dataset. Significant p values (p<0.00005) are indicated by an asterisk (*)