A heat map showing the relatedness between RILs. Relationship matrix was estimated for the relationships among the lines using marker data, which the output serves as the matrix for representing familial relatedness. The heat map displays the relationships among the 275 RILs of Set 1. The red diagonal represents perfect relationship of each line with itself, and the symmetric off-diagonal elements represent relationship measures [in this case identity by descent (IBD)] for pairs of lines. There is not an obviously block of warmer color on the diagonal which shows a cluster of closely related lines. The dendrogram (tree diagram) on the right shows the results of a cluster analysis on the IBD matrix.