plexippus belongs to the order Lepidoptera and has 30 chromosomes one of which is a neo-sex chromosome which is the result of a fusion between one of the sex chromosomes and an autosome. A study using a combination of methods (Hi-C assembly, coverage analysis and ChIp-seq) found that the neo-Z segment exhibits complete dosage compensation which is achieved by increased transcription in ZW females. Interestingly, the ancestral Z segment exhibits dosage balance with transcription levels being equal between both genders but less than the expected ancestral level, and this is achieved by decreased transcription in ZZ males. See also 2R hypothesis Barr body Gene dosage X-inactivation Tsix XY sex-determination system epigenetics References Further reading Genetics de:Gonosom#Dosiskompensation