Large palindromes on the primate X Chromosome are preserved by natural selection

Natural selection has preserved X-palindrome gene families. Results based on 12 palindromes conserved between human, chimpanzee, and rhesus macaque. (A) Square dot plot comparing structure of P25 between human and rhesus macaque. Indels highlighted in gray; nearly all fall between protein-coding genes. (B) Fraction of bases within indels for protein-coding gene sequence versus all other sequence. Results are the average of all pairwise species comparisons. Indels were defined as uninterrupted stretches of at least 1 kb in one species without orthologous sequence in the other species. (**) P < 0.01, (***) P < 0.001, Mann–Whitney U test.