Fig. 7
From: Convergent evolution of Y chromosome gene content in flies
Model of Y-linked gene content evolution in flies. The dynamics of gene content evolution in flies across time is shown. a X and Y chromosomes originate from ordinary autosomes with identical gene content. b The first genes to diverge at the DNA sequence level are genes with male-biased expression. c Over time, most genes on the Y acquire mutations, and many start to become pseudogenes. d Continuing Y degeneration, and loss of some male-biased genes on the X chromosome. e Acquisition of male-biased genes from autosomes to the Y chromosome. Genes with male-biased expression are shown by blue shading, and genes with broad functions are shown with grey shading
