Fig. 5

Three clusters of Sp185/333 genes in the sequenced genome of S. purpuratus. The genes within Clusters 1, 2 and 3 range in size from 1170 to 1894 nt and are spaced apart by 3–12.8 kb. All genes have two exons, as indicated by the rectangle (first exon) and pentagon (second exon), which also indicates gene orientation within each cluster. Element patterns are listed above each gene and are indicated in different colors as initially defined by [21], which is identified by the shaded area in Cluster 1. All genes are surrounded by GA STRs (green triangles). The long stretches of GA STRs located on both sides of Cluster 3 are positioned at distances that correlate with corresponding genes in the other clusters. This map is based on three verified BAC assemblies (accession numbers: KU668452, KU668453, KU668454). Segmental duplications are surrounded by GAT STRs (black triangles denote GAT STRs of ≥ 35 repeats and gray triangles denote GAT STRs of 4–17 repeats; see Additional file 7: Table S3). Triangle location above or below the line indicates the orientation of the STRs, which is relative to the proximal gene