Dyer, KA, White, BE, Bray, MJ, Piqué, DG and Betancourt, AJ 
ORCID: 0000-0001-9351-1413
(2011)
Molecular evolution of a y chromosome to autosome gene duplication in Drosophila
Molecular Biology and Evolution, 28 (3).
pp. 1293-1306.
ISSN 0737-4038, 1537-1719
Abstract
In contrast to the rest of the genome, the Y chromosome is restricted to males and lacks recombination. As a result, Y chromosomes are unable to respond efficiently to selection, and newly formed Y chromosomes degenerate until few genes remain. The rapid loss of genes from newly formed Y chromosomes has been well studied, but gene loss from highly degenerate Y chromosomes has only recently received attention. Here, we identify and characterize a Y to autosome duplication of the male fertility gene kl-5 that occurred during the evolution of the testacea group species of Drosophila. The duplication was likely DNA based, as other Y-linked genes remain on the Y chromosome, the locations of introns are conserved, and expression analyses suggest that regulatory elements remain linked. Genetic mapping reveals that the autosomal copy of kl-5 resides on the dot chromosome, a tiny autosome with strongly suppressed recombination. Molecular evolutionary analyses show that autosomal copies of kl-5 have reduced polymorphism and little recombination. Importantly, the rate of protein evolution of kl-5 has increased significantly in lineages where it is on the dot versus Y linked. Further analyses suggest this pattern is a consequence of relaxed purifying selection, rather than adaptive evolution. Thus, although the initial fixation of the kl-5 duplication may have been advantageous, slightly deleterious mutations have accumulated in the dot-linked copies of kl-5 faster than in the Y-linked copies. Because the dot chromosome contains seven times more genes than the Y and is exposed to selection in both males and females, these results suggest that the dot suffers the deleterious effects of genetic linkage to more selective targets compared with the Y chromosome. Thus, a highly degenerate Y chromosome may not be the worst environment in the genome, as is generally thought, but may in fact be protected from the accumulation of deleterious mutations relative to other nonrecombining regions that contain more genes. © The Author 2010. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Y Chromosome, Animals, Drosophila, Drosophila Proteins, DNA, Sequence Analysis, DNA, Sex Factors, Evolution, Molecular, Phylogeny, Gene Duplication, Recombination, Genetic, Fertility, Mutation, Genome, Female, Male, Selection, Genetic, Chromosomes, Insect |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 31 Oct 2016 09:55 |
| Last Modified: | 24 Jan 2026 00:56 |
| DOI: | 10.1093/molbev/msq334 |
| Open Access URL: | http://mbe.oxfordjournals.org/content/28/3/1293.fu... |
| Related Websites: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3004208 |
| Disclaimer: | The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate. |
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