Sexual recombination and the power of natural selection.

Theory predicts that recombination will increase the effectiveness of natural selection. A Drosophila melanogaster model system was developed that increased experimental power with the use of high experimental replication, explicit tracking of individual genes, and high but natural levels of background selection. Each of 34 independent experiments traced the fate of a newly arisen mutation located within genome-wide, synthetic chromosomes that were propagated with or without recombination. An intrinsic advantage to recombination was demonstrated by the finding that the realized strength of selection on new mutations was markedly increased when recombination was present.