Peacock wooing peahen (intersexual selection).
Male bighorn sheep butting heads in competition for females (intrasexual seleection).
It is important to break sexual selection down into its two subcategories in order to understand the role that sexual selection plays in the evolution of organisms.
Intersexual Selection[]
Also known as "mate choice," intersexual selection typically involves choosy females who pick only the showiest males as their mates.
Intrasexual Selection[]
Direct competition between members of the same sex (and same species) competing for mates of the opposite sex.