Extended Data Fig. 6: Sex chromosome evolution in monotremes.
From: Platypus and echidna genomes reveal mammalian biology and evolution
a, Mummerplot showing homology between platypus (x axis) and echidna (y axis) X chromosomes. Blue lines: forward alignment; red lines: reverse alignment. For echidna, X1, X2 and X3 are homologous to platypus X1, X2 and X3, respectively. Echidna X4 is homologous to platypus X5. And for echidna X5, it is not homologous to any platypus sex chromosome, and instead it is homologous to platypus chromosome 12. b, Homology between platypus X chromosomes (x axis) and human chromosomes (y axis). c, Homologous relationships between platypus sex chromosomes and chicken. d, Alignment between platypus and chicken showing the alternating pairing pattern of the platypus sex chromosome chain. e, X/Y pairwise dS comparison between gametologues on X1–Y5 pair (n = 18) and other sex chromosome pairs (n = 10). Box plots show median, quartiles (boxes) and range (whiskers). ***P < 0.001 (P = 0.0002954), one-sided Wilcoxon rank-sum test.
