The gene BCO2 enables male and female members of some bird species to display dramatically different color patterns.

In some finch species, the difference between colorful males and muted females comes down to one gene, BCO2, which encodes an enzyme that degrades carotenoids.

The male proboscis monkey’s large nose probably evolved in response to female preference and competition between males.

Scientists explore why male peacock spiders are so colorful. 

In Heliconius butterflies, researchers discover the importance of a male wing structure in female choice. 

Researchers find that microRNAs may play a role some of the sexual differences seen in fruit flies.

Scientists propose that hominin facial bones evolved for protection against the powerful blows of combat.

Blue badges that make female lizards less attractive to potential mates are paradoxically common.

Differential gene expression between dominant and subordinate male turkeys could help evolutionary biologists deconstruct the roots of sexual dimorphism.