Structure of the repeats within the breakpoints that converted the Standard gene arrangement into the Arrowhead arrangement. The heavy line at the bottom indicates Muller element C, and the tick marks indicate the locations of the proximal and distal breakpoints for the Arrowhead inversion. The black histograms at the top indicate the frequency that a BLAST High-scoring Segment Pair (HSP) included a particular nucleotide in BLASTN comparison of each breakpoint to the entire genome (E-value ≤1 × 10^-5). Two repeat families of 128 and 315 bp (open and filled boxes, respectively) are shown within the two breakpoint regions within the detail regions at the top of the figure. The individual repeats were labeled with a three-letter designation, where the first letter indicates proximal or distal, the number indicates the repeat family, and the last letter indicates the distinct repeat copy. Larger repeats can be generated from the small repeats such as the 443-bp repeat created by the adjacent 128- and 315-bp repeats. The dashed box indicates the putative repeat unit involved in the rearrangement event, and the triangles indicate the approximate location of the DNA breaks with respect to the repeat motif.