Meaning of VARIATION in English

VARIATION

I

In biology, any difference between cells, individual organisms, or groups of organisms within a species caused either by genetic differences (variation in genotype ) or by the effect of environmental factors on the expression of genetic potentials (variation in phenotype ).

Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behaviour, learning and mental ability, and other obvious or measurable characters. Genotypic variations are caused by differences in number or structure of chromosome s or by differences in the gene s carried by the chromosomes. Eye colour, body form, and disease resistance are genotypic variations. Phenotypic variations may result from factors such as climate, food supply, and actions of other organisms. Phenotypic variations also include stages in an organism's life cycle and seasonal variations in an individual. Because they do not involve hereditary alteration and in general are not transmitted to future generations, phenotypic variations are not important in evolution . See also polymorphism .

II

In music, basic technique consisting of changing the music melodically, harmonically, or contrapuntally.

The simplest variation type is the variation set, in which two or more sections are based on the same musical material, which is treated with different variational techniques in each section. The practice, originally involving use of a repeated bass line (basso ostinato, or ground bass), began in early 16th-century dance music in Italy and Spain. Ground-bass forms include the chaconne and passacaglia, both of which usually employ a brief bass line repeated many times. In the 17th century, organ and harpsichord variations became a standard form in Germany. Keyboard variations in the 19th century often employed popular tunes or opera melodies; variation form was also commonly used in symphonies, quartets, and sonatas. It declined in importance after the classical era but has never ceased to be employed by composers. The music of certain non-Western cultures also uses variational techniques. The art music of southern India is built on the concept of a string of pieces, each a variation on a given "theme." A somewhat different concept of multilevel variation is found in the gamelan (orchestra) music of Indonesia. The variations are not consecutive but are simultaneous, a technique called heterophony.

Britannica English dictionary.      Английский словарь Британика.