Fig. 1.

Population structure for 91 cowpea accessions. a Plot of ancestry estimates for K = 4; b geographical distribution and population structure of accessions used in this study, and inferred cowpea dispersion routes. Exact locations are provided for Iberian Peninsula accessions. For genebank accessions, coordinates were slightly adjusted in cases where latitude and longitude were identical to allow a visualization of all samples in the study. Each color represents a subpopulation as inferred by STRUCTURE (blue = subpopulation 1; red = subpopulation 2; green = subpopulation 3; orange = subpopulation 4), with ‘grey’ being used for the ‘admixed’ group (membership coefficient < 0.7). Shapes are used to distinguish the two subspecies of Vigna unguiculata used in this study, with circles representing ssp. unguiculata accessions and triangles indicating ssp. sesquipedalis accessions