DIVERGENCE

From Big Medical Encyclopedia

DIVERGENCE (late lat. divergentia discrepancy) — the divergence of characters in the course of evolution leading to emergence of morphological and functional distinctions between groups of the organisms which arose from the general ancestors. A variety of a structure of extremities of the mammals adapted for run (a hoof of a horse), a lasagna (a hand of a monkey and a didactylous paw of an idler), to swimming (flippers of a dolphin or walrus) etc. can be an example of result of action of D. All these shapes of an extremity arose by D. from an initial five-fingered extremity of primitive reptiles. The principle D. is established independently from each other by Ch. Darwin and A. Wallace.

Begins with emergence of distinctions between populations of one look (see) that is a consequence of their adaptation to unequal conditions of dwelling under action natural selection (see). At preservation of the different directions of selection of D. amplifies, leading at first to formation geographical or (and) ekol, subspecies, and then and to emergence of new types. Usually D. proceeds after formation of new types that is caused by their further adaptation to different conditions of the environment. Therefore taxonomic categories of a nadvidovy rank (childbirth, families, groups, classes, types) represent finally D.'s result of the types making these taxons.

— the most widespread type of evolution providing the fullest use with different types of conditions of the environment. In addition to D., the parallel evolution leading to emergence of identical signs at related forms is possible and also convergence (see), providing emergence of similar signs at unrelated forms.

See also Darwinism , Theory of evolution .


Bibliography: Shmalgauzen I. I. Problems of Darwinism, L., 1969, bibliogr.; Yablokov A. V. and Yusufov A. G. Theory of evolution, M., 1976, bibliogr.

L. Ya. Blyakher.

Яндекс.Метрика