(a). Organisation of UCEs and repetitive DNA in the Little Skate Hoxa cluster. (a) Location of ultraconserved non-coding elements (red) conserved at 100% over 100 bp or more between Little Skate and Horn Shark in relation to the Hox genes (blue) and (b) location of repetitive elements in the Little Skate Hoxa cluster. Simple sequence repeats are represented as purple bars, LINEs and SINEs are shown with black triangles and potential G-quadruplex forming regions are indicated by 'G4'. The positions of the four predicted non-coding RNAs are also indicated (green).