Mating-induced recombination in fruit flies.

In traditional deterministic models the conditions for the evolution of sex and sexual behavior are limited because their benefits are context dependent. In novel and adverse environments both multiple mating and recombination can help generate gene combinations that allow for rapid adaptation. Mating frequency often increases in conditions in which recombination might be beneficial; therefore, increased sexual behavior might evolve to act as a cue that stimulates recombination. We conducted two experiments in the fruit fly, Drosophila melanogaster, using linked phenotypic markers to determine how recent bouts of additional mating affect female recombination rate. The first experiment examined the effect of additional mating, mating history, and age on female recombination rate. The second experiment assessed the effect of recent mating events on recombination rate. Together, the experiments suggest that each additional bout of mating temporarily increases female recombination rate. These findings imply that the conditions favoring the evolution of sexual reproduction and multiple mating behaviors are broader than currently appreciated.