Adaptation

An adaptation is an inherited trait shaped by natural selection that improves an organism’s performance in a particular environment. Its advantage depends on environmental conditions and can change over time.

Natural selection: The process by which heritable traits that improve reproductive success become more common across generations. Differential reproductive success is the main process that shapes adaptations.
Evolution: Change in heritable characteristics of populations across generations. Adaptation is one outcome of evolutionary change, specifically shaped by selection.
Industrial melanism: An increase in dark pigmentation in populations exposed to environments where darker forms gain a survival advantage. The peppered moth illustrates how pollution changed which color pattern was advantageous.
Adaptationism: An approach that explains biological traits primarily as products of natural selection for their current functions. It can overstate how many traits are adaptations and how precisely selection shaped them.
Adaptive radiation: The diversification of a lineage into multiple forms adapted to different ecological niches. Different environments can favor divergent adaptations within a single ancestral lineage.
Heritability: The proportion of variation in a trait within a population that is associated with genetic variation. Selection can shape a trait only when relevant differences pass between generations.
Phenotype: An organism’s observable traits, arising from genetic and environmental influences. Adaptations are expressed as traits of organisms, not abstract benefits alone.
Antifreeze protein: A protein that binds ice crystals or inhibits their growth, helping organisms tolerate freezing conditions. Some polar fish use these proteins as a physiological adaptation to icy waters.
Spandrel (biology): A feature that arises as a by-product of other structural or developmental changes rather than direct selection for its function. A trait can be useful without having originated as an adaptation for that use.
Ecological niche: The environmental conditions and ecological roles under which a population persists and reproduces. An adaptation’s advantage is tied to the niche in which it operates.

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