Natural Selection Cuts Broad Swath Through Fruit Fly Genome

A new exploration of how evolution works at the genomic level may have a significant impact on drug development and other areas of medicine.

The report, published in Nature last week, offers new evidence in a longstanding debate about how organisms evolve. One well-known path to change is a heavily favorable mutation in a single gene. But it may be well known only because it is easy to study. Another path is exploitation of mildly favorable differences that already exist in many genes.

The question has considerable practical importance because if complex traits, including susceptibility to disease, are influenced by just a few genes, then it should be easy to develop treatments that target the few genes’ products. But if tens or hundreds of genes are involved in each trait, the task may be close to impossible.

Theorists have argued over this point for years, but researchers have been able to address it only recently. With advanced DNA decoding machines they can now afford to decode every DNA unit in sample genomes of a population undergoing an evolutionary change.

Three...