Figure 6

Cluster analysis of varieties. Agglomerative clustering using the un-weighted pair group method with averages (UPGMA) for 134 oat varieties using 1295 non-redundant DArT marker loci. Oat varieties are identified by truncated entry names, which are preceded by two-letter codes indicating country of origin, and by additional codes if they are winter-types (W), fall-sown but winter grown (F), or naked (N). See Additional file 1 for full entry names and country of origin codes. Clustering was implemented using the Agglomerative Nesting (AGNES) function in the R statistical environment [52]. The distance metric used was the Manhattan distance, which represents (in this case) the number of loci (out of 1295, adjusted for missing scores) for which two lines differed in their marker score. A high-resolution version of this figure is presented in Additional file 10.