Dictionary:

adaptation

  (ăd'ăp-tā'shən)

1. 1. The act or process of adapting.
   2. The state of being adapted.
2. 1. Something, such as a device or mechanism, that is changed or changes so as to become suitable to a new or special application or situation.
   2. A composition that has been recast into a new form: The play is an adaptation of a short novel.
3. Biology. An alteration or adjustment in structure or habits, often hereditary, by which a species or individual improves its condition in relationship to its environment.
4. Physiology. The responsive adjustment of a sense organ, such as the eye, to varying conditions, such as light intensity.
5. Change in behavior of a person or group in response to new or modified surroundings.

A characteristic of an organism that makes it fit for its environment or for its particular way of life. For example, the Arctic fox (Alopex lagopus) is well adapted for living in a very cold climate. Appropriately, it has much thicker fur than similar-sized mammals from warmer places; measurement of heat flow through fur samples demonstrates that the Arctic fox and other arctic mammals have much better heat insulation than tropical species. Consequently, Arctic foxes do not have to raise their metabolic rates as much as tropical mammals do at low temperatures. The insulation is so effective that Arctic foxes can maintain their normal deep body temperatures of 100°F (38°C) even when the temperature of the environment falls to −112°F (−80°C). Thus, thick fur is obviously an adaptation to life in a cold environment.

In contrast to that clear example, it is often hard to be sure of the effectiveness of what seems to be an adaptation. For example, the scombrid fishes (tunnies and mackerel) seem to be adapted to fast, economical swimming. The body has an almost ideal streamlined shape. However, some other less streamlined-looking fishes are equally fast for their sizes. There are no measurements of the energy cost of scombrid swimming, but measurements on other species show no clear relationship between energy cost and streamlining.

Evolution by natural selection tends to increase fitness, making organisms better adapted to their environment and way of life. It might be inferred that this would ultimately lead to perfect adaptation, but this is not so. It must be remembered that evolution proceeds by small steps. For example, squids do not swim as well as fish. The squid would be better adapted for swimming if it evolved a fishlike tail instead of its jet propulsion mechanism, but evolution cannot make that change because it would involve moving down from the lesser adaptive summit before climbing the higher one.

The process by which a person's body responds positively over a period of time to the effects of exercise so that the exerciser can cope with higher workloads. In a well-designed training programme, it is important to increase the workloads gradually as adaptation takes place to ensure that there is a sufficient stimulus to produce beneficial training effects (see overload principle). See also acclimatization.

noun

1. The act of making suitable to an end or the condition of being made suitable to an end: accommodation, adaption, adjustment, conformation. See change/persist.
2. Adjustment to a changing environment: acclimation, acclimatization. See change/persist.

1. an alteration that an organ or organism undergoes to adjust to its environment. 2. a close approximation of a tissue flap, an appliance, or a restorative material to natural tissue. 3. an accurate adjustment of a band or a shell to a tooth. 4. a condition in reflex activity marked by a decline in the frequency of impulses when sensory stimuli are repeated several times.

For more information on adaptation, visit Britannica.com.

The process by which the eye changes sensitivity and becomes accustomed to more or less light than it was exposed to during an immediately preceding period.

In biology, a characteristic of an organism that arose through its being naturally selected for its current use (see Darwinism). This is contrasted with an exaptation or feature that is co-opted for a use: an exaptation is a feature that will have arisen by natural selection, but for another use than the one that it currently has. A nonaptation is a feature that exists without promoting fitness for survival at all.

1. The process by which a body responds positively over a period of time to the effects of exercise so that he or she can cope with higher workloads. In a well-designed training programme, it is important to increase the workloads gradually as adaptation takes place, to ensure that there is a sufficient training stimulus (see overload principle).

2. In sociology, the manner in which any social system, such as a sports club or sporting body, responds to its environment in order to survive.

3. Sensory adaptation; a decline in the transmission of a sensory impulse when a receptor is stimulated continuously with a constant stimulus strength.

Adaptation is not part of Freudian vocabulary (it does not appear in the index of the Standard Edition, for example). The idea of adaptation, however, is present throughout Freud's work. It appears as early as 1895, in his "Project for a Scientific Psychology" (1950a), when he discusses the mechanisms of perception, attention and memory. The idea runs through all of Freud's subsequent work whenever he discusses the relation between psychic reality and the "reality of the outside world." It is found, for example, in "Instincts and their Vicissitudes" (1915c) and "Repression" (1915d), when he writes that dangers that can't be avoided through behavioral means are "rejected toward the interior." Other texts where the concept appears include "Neurosis and Psychosis" (1924b), "The Loss of Reality in Neurosis and Psychosis" (1924e), and "An Outline of Psycho-Analysis" (1940a). In fact, there are few texts by Freud where the question of adaptation isn't found, even if the word itself rarely appears.

Adaptation and the related theoretical issues are central to the development of ego-psychology, which was, for the most part, based on Freud's structural theory and the work of Anna Freud (1936/1937) and Heinz Hartmann, author of Ego Psychology and the Problem of Adaptation (1938/1958). It was in this period that a theorical schism developed, leading to differences in clinical psychoanalytic practice between those analysts (especially English-speaking) who adapted this point of view and those who preferred other options, either along the lines developed by Melanie Klein and her successors or the rather different approach taken by Lacan and his successors.

Jacques Lacan was, in fact, highly critical of the primacy given to the problems of adaptation in ego-psychology. He emphasized that naively establishing "external reality" as a given prior to and outside of psychic activity is a theoretical absurdity since that exterior reality is constructed through close interaction with psychic reality itself. He also pointed out the dangers of an analytical practice in which the analyst, within the framework of a normative and "normalizing" enterprise, developed mastery, or even a sense of excessive power, in assuming that his or her own "adaptation" is by definition better than that of the patient. Whatever one might think of these criticisms and their rebuttals, there is little doubt that they have had considerable impact, well beyond the field of Lacanian thought, especially in the French-speaking world. Unfortunately, this has had the effect of "throwing the baby out with the bathwater" through the unjustified condemnation of any psychoanalytic consideration of the problems of adaptation. These problems cannot be avoided, however, to the extent that psychic processes are constantly being adjusted in terms of their internal equilibrium and modified as a result of the impact of outside events.

Bibliography

Canguilhem, Georges. (1989). The normal and the pathological (Carolyn R. Fawcett & Robert S. Cohen, Trans.). New York: Zone Books. (Original work published 1966)

Freud, Anna. (1937). The ego and the mechanisms of defense. London: Hogarth Press. (Original work published 1936)

Freud, Sigmund. (1915c). Instincts and their vicissitudes. SE, 14: 109-140.

——. (1915d). Repression. SE, 14: 141-158.

——. (1924b [1923]). Neurosis and psychosis. SE, 19: 147-153.

——. (1924e). The loss of reality in neurosis and psychosis. SE, 19: 180-187.

——. (1940a [1938]). An outline of psycho-analysis. SE, 23: 139-207.

——. (1950a [1887-1902]). Extracts from the Fliess papers. SE, 1: 173-280.

Hartmann Heinz. (1958). Ego psychology and the problem of adaptation (David Rapaport, Trans.). New York: International Universities Press. (Original work published 1938)

—ROGER PERRON

The changes made by living systems in response to their environment. Heavy fur, for example, is one adaptation to a cold climate.

1. adjustment of the pupil to light, constricting with increased light intensity, dilating with decreased intensity.
2. any anatomical, physiological, developmental or behavioral adjustment to the environment of an organism which enhances its chances of leaving descendants. The ability of animals to adapt to a limited supply of drinking water and to high or low environmental temperatures is an important aspect of animal husbandry. The selection of animals which are capable of a high level of such adaptation has made it possible to improve the productivity of herds and flocks in some countries. See also general adaptation syndrome.
3. the process by which organisms are modified so as to improve their chances of survival in an environment.

• dark a. — adaptation of the eye to vision in the dark or in reduced illumination.
• light a. — adaptation of the eye to vision in sunlight or in bright illumination (photopia), with reduction in the concentration of the photosensitive pigments of the eye.
• negative a. — see habituation.
• a. rate — the rate at which afferent sensory receptors discharge into their afferent axons. The rates differ between different types of receptors. For example, there are slow adaptors which signal the more persistent changes such as steady pressure. See also receptor adaptation (below).
• receptor a. — sensory receptors vary in their individual response to stimuli, the response declining after an initial period of rapid response. The rate at which different kinds of receptors change these responses is the adaptation rate (see above).

For other uses, see Adaptation (disambiguation).

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Biology Portal ·

An adaptation is a positive characteristic of an organism that has been favored by natural selection.^[1] The concept is central to biology, particularly in evolutionary biology. The term adaptation is also sometimes used as a synonym for natural selection,^{[citation needed]} but most biologists discourage this usage.

Overview

Organisms that are adapted to their environment are able to:

• Obtain air, water, food and nutrients.
• Cope with physical conditions such as temperature, light and heat.
• Defend themselves from their natural enemies.
• Reproduce.
• Respond to changes around them.

Adaptations enable living organisms to cope with environmental stresses and pressures. Adaptation can be structural or behavioral. Structural adaptations are special body parts of an organism that help it to survive in its natural habitat (e.g., skin color, shape, body covering). Behavioral adaptations are special ways a particular organism behaves to survive in its natural habitat. Physiological adaptations are systems present in an organism that allow it to perform certain biochemical reactions (e.g., making venom, secreting slime, being able to keep a constant body temperature).

Adaptations are traits that have been selected for by natural selection. The underlying genetic basis for the adaptive trait did not arise as a consequence of the environment; the genetic variant pre-existed and was subsequently selected because it provided the bearer of that variant some advantage. The first experimental evidence of the pre-exisiting nature of genetic variants was provided by Joshua Lederberg and colleagues who developed fluctuation analysis, a method to show the random fluctuation of pre-exisitng genetic changes that conferred resistance to antibiotics by the bacterium Escherichia coli

While many traits have obvious adaptive purposes, it is worthwhile to point out that many traits are not adaptive, that is, there is no obvious reason scientists can divine for the presence of a certain trait. This situation is common and there are many causes: the utility of a trait is lost and hence does not now appear adaptive, the utility of a trait is unknown, the trait is a consequence of another trait that is adaptive (the Spandrel idea). This observation underscores two other important points: genetic variants arise randomly and hence traits can appear randomly and that because the environment for all living things is constantly in flux, the utility of adaptations will naturally ebb and flow.

Organisms that are not suitably adapted to their environment will either have to move out of the habitat or die out. The term die out in the context of adaptation simply means that the death rate over the entire species (population, gene pool ...) exceeds the birth rate for a long enough period for the species to disappear; due to individual phenotypic plasticity, individuals will be more or less successful. The opposite is selection which in this context means that the birth rate of those carrying the adaptive trait and the hence the underlying genetic variant exceeds over time the birth rate of those that do not carry the adaptive trait.

Adaptation vs. adaptiveness

A trait being adaptive, i.e. increasing the organism's fitness, is neither a necessary nor sufficient condition for it to be an adaptation.^[2] 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

There is a great difference between adaptation and acclimation. 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 to the pressure and function and no longer notice the change. This ability to acclimate is an adaptation, but not the acclimation 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.

Theories

Jean-Baptiste Lamarck

The 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 theory.

Although the vast majority of genetic variants arising from errors of DNA replication or recombination do not confer any advantage to an individual organism, the multitude of variation contained within the collective genomes of a species provides much material for natural selection to work upon allowing many adaptations to be manifest.

See also

• Adaptationism
• Adaptive radiation
• Coadaptation
• Exaptation
• Dual inheritance theory
• Gene-centered view of evolution
• Habituation
• Intragenomic conflict
• Lamarckism
• Neutral theory of molecular evolution
• Preadaptation
• Spandrel

References

1. ^ Sterelny, K. & Griffiths, P. E. (1999) Sex and Death: An Introduction to Philosophy of Biology p.217 University of Chicago Press. ISBN O-226-77304-3
2. ^ Sober, E. (1993) Philosophy of Biology. p.84 Boulder: Westview Press.

Basic topics in evolutionary biology
Evidence of evolution
Processes of evolution	Adaptation · Macroevolution · Microevolution · Speciation
Population genetic mechanisms	natural selection · genetic drift · gene flow · mutation
Evolutionary developmental biology (Evo-devo) concepts	Phenotypic plasticity · Canalisation · Modularity
Modes of evolution	Anagenesis · Catagenesis · Cladogenesis
History	History of evolutionary thought · Charles Darwin · The Origin of Species · Modern evolutionary synthesis · Evolutionary history of life
Other subfields	Ecological genetics · Human evolution · Molecular evolution · Phylogenetics · Systematics
List of evolutionary biology topics · Timeline of evolution

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Dansk (Danish)
n. - tilpasning, tilpasningsproces, afpasning, indretning

Nederlands (Dutch)
aanpassing, bewerking televisiebewerking

Français (French)
n. - adaptation

Deutsch (German)
n. - Anpassung, Adaptation, Adaption

Ελληνική (Greek)
n. - προσαρμογή, διασκευή

Italiano (Italian)
adattamento, assimilazione

idioms:

• screen adaptation    adattamento cinematografico
• stage adaptation    adattamento teatrale
• television adaptation    adattamento televisivo

Português (Portuguese)
n. - adaptação (f), ajuste (m), alteração (f)

idioms:

• screen adaptation    adaptação para o cinema (Cin.)
• stage adaptation    adaptação para o teatro
• television adaptation    adaptação para a televisão

Русский (Russian)
приспособление, адаптация

idioms:

• screen adaptation    киноверсия
• stage adaptation    сценический вариант пьесы
• television adaptation    телеверсия

Español (Spanish)
n. - adaptación

Svenska (Swedish)
n. - anpassning, bearbetning

中文（简体） (Chinese (Simplified))
适应, 改写本, 改编, 适应作用, 适应性的变化

中文（繁體） (Chinese (Traditional))
n. - 適應, 改寫本, 改編, 適應作用, 適應性的變化

한국어 (Korean)
n. - 적합, 개작

日本語 (Japanese)
n. - 適合, 順応, 改作

العربيه (Arabic)
‏(الاسم) تكييف, تكيف, شيء معدل‏

עברית (Hebrew)
n. - ‮התאמה, סיגול, עיבוד‬

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