Natural selection that maintains multiple alleles in a population at frequencies higher than would be expected by chance alone. It preserves genetic diversity rather than eliminating variation.
From 'balance' derived from Latin 'bilanx' meaning 'having two scales' and 'selection' from Latin 'selectio' meaning 'choice'. The term emerged in evolutionary biology in the 1950s to describe selection that maintains equilibrium rather than driving change.
Balancing selection is why blood types haven't disappeared - each type offers different advantages against different diseases! It's evolution's way of keeping multiple genetic 'tools' in the toolkit because you never know which one you'll need next.
Complete word intelligence in one call. Free tier — 50 lookups/day.