|the offspring of a zebra and a donkey.|
|a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.|
|adaptation (ˌædəpˈteɪʃən, ˌædæp-)|
|1.||the act or process of adapting or the state of being adapted; adjustment|
|2.||something that is produced by adapting something else|
|3.||something that is changed or modified to suit new conditions or needs|
|4.||biology an inherited or acquired modification in organisms that makes them better suited to survive and reproduce in a particular environment|
|5.||physiol the decreased response of a sense organ to a repeated or sustained stimulus|
|6.||psychol (in learning theory) the weakening of a response to a stimulus with repeated presentation of the stimulus without reinforcement; applied mainly to innate responses|
|7.||social welfare alteration to a dwelling to make it suitable for a disabled person, as by replacing steps with ramps|
adaptation ad·ap·ta·tion (ād'āp-tā'shən)
The acquisition of modifications in an organism that enable it to adjust to life in a new environment.
An advantageous change in the function or constitution of an organ or tissue to meet new physiological conditions.
Adjustment of the pupil and retina to varying degrees of illumination.
A property of certain receptors through which they become less responsive or cease to respond to repeated or continued stimuli of constant intensity.
The fitting, condensing, or contouring of a restorative dental material to a tooth or cast.
The dynamic process in which the behavior and physiological mechanisms of an individual continually change to adjust to variations in living conditions.
|adaptation (ād'āp-tā'shən) Pronunciation Key
A change in structure, function, or behavior by which a species or individual improves its chance of survival in a specific environment. Adaptations develop as the result of natural selection operating on random genetic variations that are capable of being passed from one generation to the next. Variations that prove advantageous will tend to spread throughout the population.
Our Living Language : The gazelle is extremely fast, and the cheetah is even faster. These traits are adaptations—characteristics or behaviors that give an organism an edge in the struggle for survival. Darwinian theory holds that adaptations are the result of a two-stage process: random variation and natural selection. Random variation results from slight genetic differences. For example, one cheetah in a group may be slightly faster than the others and thus have a better chance of catching a gazelle. The faster cheetah therefore has a better chance of being well-fed and living long enough to produce offspring. Since the cheetah's young have the same genes that made this parent fast, they are more likely to be fast than the young of slower cheetahs. The process is repeated in each generation, and thereby great speed becomes an adaptation common to cheetahs. This same process of natural selection, in which the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated, also favors the fastest gazelles. Though evolution, in this case, may be thought of as an "arms race," animals may also adapt to their environment in a process known as adaptive radiation, as the so-called Darwin's finches in the Galápagos have done. On the islands, one type of finch gradually gave rise to some 13 different species of birds with differently shaped beaks, each species having adapted to its varying food niches and feeding habits. And, though we seldom think of it, humans also have an impact on an organism's adaptation to its environment. For instance, because of the misuse of antibiotics, some disease-causing bacteria have rapidly adapted to become resistant to the drugs.
The changes made by living systems in response to their environment. Heavy fur, for example, is one adaptation to a cold climate.