An explicit signature of balancing selection for color-vision variation in new world monkeys

Using fecal DNA, the authors were able to sequence the L-M (red-green) opsin gene in wild spider monkeys (Ateles geoffroyi) and capuchins (Cebus capucinus). They found that these populations showed greater polymorphism in this gene than other DNA reference points, providing evidence that balancing selection is acting on color vision in New World primates.