Fig. 6

Examples of gene transposition to autosomes compensating for delayed, lineage-specific loss of homologous Y-chromosome genes: a phylogenetic perspective. Phylogenetic tree representing evolutionary relationships among mammalian species analyzed in the current study. Branch lengths are proportional to lineage divergence times; time scale in millions of years is shown at bottom. Gene loss and addition events are placed on particular branches of the tree according to species distribution patterns; precise timing of events is not known. Gene loss events (Y-linked gene loss or X-linked gene loss) are indicated by orange arrows; gene addition events (autosomal retrogene formation or gene transposition) are indicated by blue arrows. Gene names are color-coded to indicate chromosomal location: Y-linked (blue), autosomal (green), and X-linked (pink)