An adaptation is a positive characteristic of an organism that has been favored by natural selection and increases the fitness of its possessor. Of course, an adaptation must have been adaptive at some point in an organism's evolutionary history, but such an organism's environment and ecological niche can change over time, leading to adaptations becoming redundant or even a hindrance (maladaptations). Such adaptations are termed vestigial.
Adaptation vs. acclimation
"Adaptation" is also sometimes used to refer to a change in an individual organism over the course of its life that makes it more suited to the environment. For an example, see Adaptation (eye). More specifically, however, such changes are referred to as acclimation or acclimatization, the former generally being a very short-term response such as shivering, the latter being a longer-term change such as sun tanning.
There is a great difference between selective adaptation and acclimatization. Adaptation occurs over many generations; it is a gradual process caused by natural selection. Acclimatization generally occurs within a single lifetime and copes with issues that are less threatening. For example, if a human was to move to a higher altitude, respiration and physical exertion would become a problem, but after spending time in high altitude conditions one may acclimate or acclimatize to the pressure and function and no longer notice the change. This ability to acclimate is an adaptation, but not the acclimatization itself. A counter-adaptation is an adaptation that has evolved due to the selective pressure of another adaptation. This occurs in an evolutionary arms race, where a new adaptation giving one species an advantage is countered by the appearance and spread of a new feature that reduces the effectiveness of the first adaptation.
TheoriesThe theory of adaptation was first put forth by Jean-Baptiste Lamarck. His theories are also referred to as the inheritance of acquired traits.
Lamarck's theory was for a time held as an alternative scientific explanation for evolutionary change observed by Darwin in the The Origin of Species. The classic giraffe analogy offers the best delineation between the two.
- According to Darwin, more long-necked giraffes reproduce than short-necked giraffes and as such giraffes today have long necks.
- According to Lamarck, it was giraffes stretching their necks in response to higher leaves that resulted in giraffes having long necks. (This trait being passed on to the next generation)
Although neither theory in its conception could provide a complete description of the mechanism of transmission of trait variation (i.e., particulate inheritance), many recognized Darwin's theory immediately upon publication as a more complete and empirically supported theory. Modern genetics have since established the fundamental implausibility of Lamarckian inheritance, due to the one-way nature of transcription. However, see epigenetics and Baldwinian evolution for analogous processes in modern evolutionary.
adaption in Arabic: تكيف
adaption in Bulgarian: Адаптация
adaption in Czech: Adaptace
adaption in Danish: Adaptation
adaption in German: Evolutionäre Anpassung
adaption in Estonian: Kohastumus
adaption in Spanish: Adaptación biológica
adaption in Esperanto: Adaptado
adaption in French: Adaptation (biologie)
adaption in Indonesian: Adaptasi
adaption in Italian: Adattamento
adaption in Hebrew: הסתגלות אבולוציונית
adaption in Lithuanian: Adaptacija
adaption in Hungarian: Adaptáció
adaption in Japanese: 適応
adaption in Norwegian Nynorsk: Tilpassing
adaption in Uzbek: Moslashish (biologiya)
adaption in Polish: Adaptacja (biologia)
adaption in Portuguese: Adaptação (biologia)
adaption in Russian: Адаптация (биология)
adaption in Serbian: Адаптација
adaption in Serbo-Croatian: Adaptacija
adaption in Finnish: Adaptaatio
adaption in Tajik: Адаптатсия
adaption in Ukrainian: Адаптація (біологія)
adaption in Chinese: 適應