Abstract
Population geneticists remain unsure of the forces driving the evolution of Y chromosomes. Here we consider the possibility that the degeneration of the Y reflects its inability to evolve adaptively. Because the overwhelming majority of favorable mutations on a nonrecombining proto-Y suffer a zero probability of fixation, the fitness of the Y must lag far behind that of the recombining X. At some point, this disparity will grow so large that selection favors an increase in the expression of (fit) X-linked alleles and a decrease in the expression of (unfit) Y-linked alleles. Our calculations suggest that this process acts far more rapidly than hitchhiking-induced erosion of the Y and at least as rapidly as the fixation of deleterious alleles on the Y by background selection. Most important, this hypothesis can explain the evolution of Y chromosomes in taxa such as Drosophila that have very large population sizes.
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Selected References
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- Barton N. H. Linkage and the limits to natural selection. Genetics. 1995 Jun;140(2):821–841. doi: 10.1093/genetics/140.2.821. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Charlesworth B., Charlesworth D. Rapid fixation of deleterious alleles can be caused by Muller's ratchet. Genet Res. 1997 Aug;70(1):63–73. doi: 10.1017/s0016672397002899. [DOI] [PubMed] [Google Scholar]
- Charlesworth B. Model for evolution of Y chromosomes and dosage compensation. Proc Natl Acad Sci U S A. 1978 Nov;75(11):5618–5622. doi: 10.1073/pnas.75.11.5618. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Charlesworth B. The effect of background selection against deleterious mutations on weakly selected, linked variants. Genet Res. 1994 Jun;63(3):213–227. doi: 10.1017/s0016672300032365. [DOI] [PubMed] [Google Scholar]
- Charlesworth B. The evolution of chromosomal sex determination and dosage compensation. Curr Biol. 1996 Feb 1;6(2):149–162. doi: 10.1016/s0960-9822(02)00448-7. [DOI] [PubMed] [Google Scholar]
- Goodfellow P., Banting G., Sheer D., Ropers H. H., Caine A., Ferguson-Smith M. A., Povey S., Voss R. Genetic evidence that a Y-linked gene in man is homologous to a gene on the X chromosome. Nature. 1983 Mar 24;302(5906):346–349. doi: 10.1038/302346a0. [DOI] [PubMed] [Google Scholar]
- Moriyama E. N., Powell J. R. Intraspecific nuclear DNA variation in Drosophila. Mol Biol Evol. 1996 Jan;13(1):261–277. doi: 10.1093/oxfordjournals.molbev.a025563. [DOI] [PubMed] [Google Scholar]
- Muller H J. Genetic Variability, Twin Hybrids and Constant Hybrids, in a Case of Balanced Lethal Factors. Genetics. 1918 Sep;3(5):422–499. doi: 10.1093/genetics/3.5.422. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peck J. R. A ruby in the rubbish: beneficial mutations, deleterious mutations and the evolution of sex. Genetics. 1994 Jun;137(2):597–606. doi: 10.1093/genetics/137.2.597. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rice W. R. Genetic hitchhiking and the evolution of reduced genetic activity of the Y sex chromosome. Genetics. 1987 May;116(1):161–167. doi: 10.1093/genetics/116.1.161. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stephan W., Chao L., Smale J. G. The advance of Muller's ratchet in a haploid asexual population: approximate solutions based on diffusion theory. Genet Res. 1993 Jun;61(3):225–231. doi: 10.1017/s0016672300031384. [DOI] [PubMed] [Google Scholar]