Idioadaptation

one of the main trends in evolution, in which frequent changes in the structure and function of organs occur, while as a whole the level of organization of the ancestral forms is preserved. The term was introduced by A. N. Severtsov. Along with the concept of idioadaptation, such terms as clado-genesis and allomorphosis, or allogenesis, are used in the literature. Idioadaptation leads to wide distribution of a group of organisms and to its division into many related branches (adaptive radiation). Thus, the Coelenterata—Hydrozoa, Scyphozoa, Actinozoa, and Ctenophora—are widely distributed and, despite the diversity of dimensions and forms and diverse conditions of existence, have preserved the general type of organization of diploblastic animals.