1. Howard Hughes Medical Institute, Whitehead Institute, and Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA
2. Genome Sequencing Center, Washington University School of Medicine, 4444 Forest Park Boulevard, St Louis, Missouri 63108, USA

Correspondence to: David C. Page¹ Correspondence and requests for materials should be addressed to D.C.P. (Email: page_admin@wi.mit.edu). GenBank accession numbers for CERV1 and CERV2 are AY692036 and AY692037, respectively. GenBank accession numbers for all complementary DNA sequences are listed in Supplementary Table 5; accession numbers for all BAC and fosmid clones are listed in Supplementary Table 6.

The human Y chromosome, transmitted clonally through males, contains far fewer genes than the sexually recombining autosome from which it evolved. The enormity of this evolutionary decline has led to predictions that the Y chromosome will be completely bereft of functional genes within ten million years^{1, 2}. Although recent evidence of gene conversion within massive Y-linked palindromes runs counter to this hypothesis, most unique Y-linked genes are not situated in palindromes and have no gene conversion partners^{3, 4}. The 'impending demise' hypothesis thus rests on understanding the degree of conservation of these genes. Here we find, by systematically comparing the DNA sequences of unique, Y-linked genes in chimpanzee and human, which diverged about six million years ago, evidence that in the human lineage, all such genes were conserved through purifying selection. In the chimpanzee lineage, by contrast, several genes have sustained inactivating mutations. Gene decay in the chimpanzee lineage might be a consequence of positive selection focused elsewhere on the Y chromosome and driven by sperm competition.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.