Figure S2.

Geographic Prediction from SPA Suggests that a Simple Isolation-by-Distance Model Does Not Hold, Related to Figure 3

(A and B) Under this model, if geographic gradients of SNPs were smooth, the collection locations of the accessions should be recovered in the SPA analysis in B. They are not. Instead, we find strong spatial gradients between, and gentle gradients within groups.

(C and D) The strength of these gradients is disproportionately influenced by the relict and UK accessions.

(E) Finer geographic gradients of SNP variation, especially in Southern Swedish populations, are observable when relict and UK accessions are excluded.

Note that unsupervised predictions from SPA analysis are translation, scale, and rotation invariant (dimensionless).