Drosophila melanogaster mutation accumulation. Drosophila melanogaster breed:Dahomey

Variation in mutation has implications from evolution to public health. We sequenced >100 Drosophila mutation accumulation lines from high- or low-quality genetic backgrounds. We find that the rate of single base pair mutations is the same across backgrounds but low quality backgrounds suffer twice as many small insertions and deletions (indels). Given that indels are particularly harmful, this result alters evolutionary predictions and implies that some individuals are at increased risk of genetic disorders. In contrast, gene conversion occurred twice as often in high-quality backgrounds. We also find that mutation depends on local sequence context, which has significant consequences for methods of genomic inference used in evolutionary and medical genetics.