Fig. 4.
The sex chromosomes have three distinct evolutionary strata. Synonymous divergence (dS) between the X and Y chromosome was estimated for every annotated transcript on the X chromosome. Genes are ordered by position on the X chromosome (Mb). Median divergence across each stratum is shown by the red line; values are given in Table 1. Strata breakpoints are indicated by the vertical dashed lines. The centromere is indicated by a black circle. The pseudoautosomal region (positions before 2.5 Mb) is not shown. Genes with dS divergence above 0.5 are not shown