Cumulative distributions of the sex-specific repeats identified from the sex-determining chromosome regions. (A) The accumulative number of each sex-specific repeat in the hermaphrodite-specific Y (HSY) chromosome region. (B) The accumulative number of each sex-specific repeat in the HSY-corresponding X region. In total, 21 sex-specific repeats were identified from the sex determining region; 20 from the HSY and one from the corresponding X. Most of HSY-specific repeats were located in two regions where the HSY expansion occurred.