Abstract
Population genetics models show that, under certain conditions, the X chromosome is expected to be under more efficient selection than the autosomes. This could lead to 'faster-X evolution', if a large proportion of mutations are fixed by positive selection, as suggested by recent studies in Drosophila. We used a multispecies approach to test this: Muller's element D, an autosomal arm, is fused to the ancestral X chromosome in Drosophila pseudoobscura and its sister species, Drosophila affinis. We tested whether the same set of genes had higher rates of non-synonymous evolution when they were X-linked (in the D. pseudoobscura/D. affinis comparison) than when they were autosomal (in Drosophila melanogaster/Drosophila yakuba). Although not significant, our results suggest this may be the case, but only for genes under particularly strong positive selection/weak purifying selection. They also suggest that genes that have become X-linked have higher levels of codon bias and slower synonymous site evolution, consistent with more effective selection on codon usage at X-linked sites.
Original language | English |
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Pages (from-to) | 421-431 |
Number of pages | 11 |
Journal | Genetics Research |
Volume | 90 |
Issue number | 5 |
DOIs | |
Publication status | Published - Oct 2008 |
Keywords
- animals
- drosophila
- drosophila proteins
- evolution, molecular
- female
- genes, insect
- genes, x-linked
- male
- molecular sequence data
- sequence analysis, DNA
- species specificity
- X chromosome