Prairie voles are small Midwestern rodents known for monogamous behavior. But some males are also known to stray and seek out other females.

A new study reports that mating preferences in the voles are linked to genetic differences, and that both monogamous and nonmonogamous males are readily found in nature. The study appears in the journal Science.

Generally, animal neuroscientists believe that natural selection minimizes genetic variation. In this case, however, one mating strategy does not seem to be more successful than the other.

Monogamous males stay near their nests, which ensures that female mates remain faithful. Promiscuous males have more partners, but they also lose sight of their own mates.