MBE Advance Access originally published online on March 9, 2005
Molecular Biology and Evolution 2005 22(6):1423-1432; doi:10.1093/molbev/msi128
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Positive and Negative Selection on Mammalian Y Chromosomes
School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
E-mail: d.filatov{at}bham.ac.uk.
Y chromosomes are genetically degenerate in most organisms studied. The loss of genes from Y chromosomes is thought to be due to the inefficiency of purifying selection in nonrecombining regions, which leads to the accumulation of deleterious mutations via the processes of hitchhiking, background selection, and Muller's ratchet. As the severity of these processes depends on the number of functional genes linked together on the nonrecombining Y, it is not clear whether these processes are still at work on the old, gene-poor mammalian Y chromosomes. If purifying selection is indeed less efficient in the Y-linked, compared to the X-linked genes, deleterious nonsynonymous substitutions are expected to accumulate faster on the Y chromosome. However, positive selection on Y-linked genes could also increase the rate of amino acid–changing substitutions. Thus, the previous reports of an elevated nonsynonymous substitution rate in Y-linked genes are still open to interpretation. Here, we report evidence for positive selection in two out of three studied mammalian Y-linked genes, suggesting that adaptive Darwinian evolution may be common on mammalian Y chromosomes. Taking positive selection into account, we demonstrate that purifying selection is less efficient in mammalian Y-linked genes compared to their X-linked homologues, suggesting that these genes continue to degenerate.
Key Words: adaptive evolution • mammalian sex chromosomes
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. Engelstadter Muller's Ratchet and the Degeneration of Y Chromosomes: A Simulation Study Genetics, October 1, 2008; 180(2): 957 - 967. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Bachtrog The Temporal Dynamics of Processes Underlying Y Chromosome Degeneration Genetics, July 1, 2008; 179(3): 1513 - 1525. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. H. Perry, R. Y. Tito, and B. C. Verrelli The Evolutionary History of Human and Chimpanzee Y-Chromosome Gene Loss Mol. Biol. Evol., March 1, 2007; 24(3): 853 - 859. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. J. Lawson Handley, L. Berset-Brandli, and N. Perrin Disentangling Reasons for Low Y Chromosome Variation in the Greater White-Toothed Shrew (Crocidura russula) Genetics, June 1, 2006; 173(2): 935 - 942. [Abstract] [Full Text] [PDF]
|
|