Definition
Sexual Selection is a mode of natural selection where members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection).
Why It Matters
Sexual selection is the ‘driver of extravagance’ in biology; it explains traits that seem ‘useless’ for survival but are critical for reproduction, highlighting the role of costly, honest signaling in all complex systems.
Core Concepts
- Honest Signaling: Traits that are costly to maintain (like a peacock’s tail) serve as proof of genetic fitness, as only high-quality individuals can afford the “handicap.”
- Sexual Dimorphism: Differences in appearance between males and females of the same species.
- Runaway Selection: A feedback loop where a preference for a trait and the trait itself both become more extreme over generations.