An adaptation is defined by National Geographic as a genetic change in the structure or habits of an organism to allow it to survive, protect itself and reproduce in its environment. Physical adaptations, such as plants that develop thick stems to store water in deserts, manifest in the structure of the organism, while behavioral adaptations, such as animals that migrate to raise offspring, appear as a social trait.
Physical adaptations include teeth, body coverings and movement, and behavioral adaptations include social behavior, migration and protective actions. National Geographic explains how certain adaptations, called exaptations, can develop for one purpose and later be used for another, such as bird feathers created for warmth and eventually used for flight. Other adaptations, termed vestigial, become useless but remain with the organism, such as the non-functioning leg bones still found in dolphins.
Reasons for adaptations to occur include environmental, lifestyle or relationship changes, some of which are due to human intervention, according to New World Encyclopedia. In rare cases, adaptations can result in maladaptation, which decreases the survival rate. Often, adaptations develop slowly over many generations in a species. Adaptations contribute to diversity in species. However, organisms that are unable to adapt can become extinct over time.