Schematic model for sex chromosome evolution in the three pygopodids. APA, LBU and DIN represent Aprasia parapulchella, Lialis burtonis and Delma inornata, respectively. Chromosome data of L. burtonis and D. inornata were obtained from Gorman and Gress  and King . Phylogeny is modified after Jennings et al.  and Oliver and Sanders . Possible chromosome rearrangements in sex chromosome evolution in the three pygopodids are shown on each of the branch.