Adaptation

Definition

An evolutionary process, state, or trait by which a population becomes better suited to its environment through natural selection. As a process, adaptation is the cumulative change in allele frequencies that increases fitness; as a state, it describes the degree of environmental fit achieved; as a trait, it is any heritable phenotype—morphological, physiological, or behavioral—that confers a functional advantage and has been shaped by selection. In arthropods, adaptations range from cuticular hydrocarbons that reduce water loss in desert beetles to Müllerian mimicry in aposematic butterflies and silk production in spiders.

Etymology

From Latin adaptare, to fit or adjust

Example

The evolution of insecticide resistance in the Colorado potato beetle (Leptinotarsa decemlineata) is a well-documented adaptation: populations exposed to repeated chemical treatments have developed enhanced detoxification enzymes and target-site insensitivity, representing both the process of selection and the resulting adaptive trait.

Synonyms

• adaptive trait
• evolutionary adaptation

Related Terms

• Fitness
• Natural selection
• phenotypic plasticity
• exaptation
• maladaptation
• local adaptation
• cryptic coloration
• mimicry

Usage Notes

Distinguish adaptation (evolutionary, heritable change across generations) from acclimation or acclimatization (physiological adjustment within an individual's lifetime). Specialists often specify which meaning is intended: 'the process of adaptation' versus 'an adaptation.' The term carries no implication of perfection—adaptations are context-dependent and may become maladaptive when environments change. Contrast with exaptation, where a trait evolved for one function is co-opted for another.