Movie S1. Early stages of rotation in D. melanogaster strains with different sex comb lengths. In the different lines, both sex comb and distal transverse row begin as a relatively parallel row of bristles. However, as rotation proceeds, the distal transverse is displaced proximally to different degrees depending on sex comb length. Sex comb and distal transverse row are enclosed in red and yellow polygons, respectively. Artificial selected line for a high (High line) and low (Low line) number of sex comb teeth. AP, after pupariation; babPR72, bric à bracPR72.