Natural selection explains how heritable variation, selection pressures, differential survival, reproduction and allele-frequency changes drive evolutionary adaptation in populations in evolving populations.
Coverage 2010–2025 · Updated 16 Jul 2026
• Natural selection is the mechanism driving evolutionary change
• It acts on heritable variation and can produce adaptation, speciation, and biodiversity
• Mutation creates new alleles, especially when germ-line mutations are inherited
• Meiosis and random fertilization create new combinations of existing alleles
• Overproduction of offspring leads to high mortality in limited environments
• Competition for food, space, mates, and other resources promotes selection
• Abiotic factors can act as density-independent selection pressures
• Temperature, drought, light, salinity, and pH can favour different variants
• Individuals vary in adaptation, survival, and reproductive success
• Fitness means passing alleles to offspring in a particular environment
• Natural selection causes evolution only if traits are heritable
• Acquired characteristics are not inherited through DNA base sequences
• Sexual selection favours traits that increase mate choice or mating competition success
• Displays, ornaments, and behaviours such as birds-of-paradise plumage can be selected
• Selection can be modelled by experimentally controlling selection pressures
• Endler's guppy experiments test predation pressure, colour pattern, and mating success
