adaptation

In biology, any feature in the structure or function of an organism that allows it to survive and reproduce more effectively in its environment. Much adaptation is inherited (see inheritance) and is the result of many thousands of years of evolution. It is thought to occur as a result of random variation in the genetic make-up of organisms coupled with natural selection. Species become extinct when they are no longer adapted to their environment.

Adaptations to cope with changing seasons can be quite different from one organism to another. Some plants die back to survive the winter and have specially protected structures such as tight buds on a twig or a bulb underground. These structures may store food so that growth can start rapidly in spring. A carrot, for example, stores sugars for this reason. Some animals, such as swallows, may migrate, while other animals, such as the dormouse, may hibernate, allowing the body temperature and heart rate to drop in the winter.

Adaptations also occur as a result of an animal evolving into an efficient predator. A predator may have forward facing eyes, acute vision and sense of smell, and have claws, talons, or a beak for killing. The prey also adapt as a result of evolution. Prey may have eyes on the side of their heads for a wide field of view, acute hearing and sense of smell, be easily startled, be nocturnal, and be camouflaged.

In evolution, adaptation is the result of natural selection. Inherited variation usually occurs in a species. If the environment changes in some way, such as the winters becoming more severe, those individuals possessing genes that allow them to survive and reproduce more successfully pass their genes to their offspring more than those that do not. Some genes therefore become more common in the species, leading to an evolutionary change that enables the species to be better adapted to the changed environment.

Results of adaptation Adaptation produces individuals whose genetically determined characteristics allow them to survive and reproduce more effectively. Thus, the webbed feet of ducks or otters are adaptations to living in water, enabling them to swim more efficiently. In physiology, adaptation is said to occur in sense organs when the sensitivity of an organ alters in response to changes in environmental conditions. Examples include an increase in the size of the pupil of the eye to admit more light as night falls.