fig0030: Population structure revealed by PPY23. Interpolated maps depict the first MDS components of pairwise RST values for PPY23. (a) Two-dimensional MDS analysis for the whole data set (129 populations); (b) four-dimensional MDS analysis for populations of European residency and ancestry alone (68 populations). Sample locations are marked in white. Color coding is on an arbitrary rainbow scale that assigns yellow and magenta to the opposite ends of the scale.

Mentions: Multidimensional scaling (MDS) analysis was performed based upon linearized RST, separately for the five marker sets, considering either all 129 populations or the 68 populations of European residency and ancestry alone. When assessed for the PPY23 marker panel, Kruskal's stress value showed a clear ‘elbow’ with increasing dimensionality in both population sets, pinpointing an optimal trade-off between explained variation and dimensionality. For the worldwide analysis, two MDS components were optimal with PPY23 whereas four components were deemed optimal for the Europeans-only analysis. Both solutions explained the haplotypic variation well, with R2 = 95.1% in the worldwide analysis and R2 = 99.2% in the Europeans-only analysis. For comparability, MDS analyses for other marker panels were carried out with two or four dimensions, respectively. Haplotypic variation among populations within continental groups was lower than between continental groups (Fig. S3). For all five marker sets, the first MDS component clearly separated the African populations from the non-African populations (Fig. 6a, Fig. S4). Moreover, MDS also confirmed the previously reported East–West separation in the Y-STR haplotype variation [32] in the European analysis (Fig. 6b, Fig. S5). Higher MDS components were strongly dependent upon the respective marker set (Figs. S4–S6) and lacked comparably clear population patterns.