Publication Date:
2012-12-13
Description:
The relative importance of mutation, selection, and biased gene conversion to patterns of base composition variation in Drosophila melanogaster , and to a lesser extent, D. simulans , has been investigated for many years. However, genomic data from sufficiently large samples to thoroughly characterize patterns of base composition polymorphism within species have been lacking. Here, we report a genome-wide analysis of coding and noncoding polymorphism in a large sample of inbred D. melanogaster strains from Raleigh, North Carolina. Consistent with previous results, we observed that AT mutations fix more frequently than GC mutations in D. melanogaster . Contrary to predictions of previous models of codon usage in D. melanogaster , we found that synonymous sites segregating for derived AT polymorphisms were less skewed toward low frequencies compared with sites segregating a derived GC polymorphism. However, no such pattern was observed for comparable base composition polymorphisms in noncoding DNA. These results suggest that AT-ending codons could currently be favored by natural selection in the D. melanogaster lineage.
Electronic ISSN:
1759-6653
Topics:
Biology
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