convergence in biology

From Big Medical Encyclopedia

CONVERGENCE in biology (Latin convergere to meet, approach) — formation at unrelated, phylogenetic far organisms of signs (structures, bodies) performing similar function. To. forms as a result of existence of organisms in similar conditions of the environment and equally directed process natural selection (see). To. it is accepted to distinguish from parallelism where it is about acquisition of similar signs within group of related organisms. To. it is, as a rule, limited not to all, and only nek-ry bodies (see. Similar bodies ). Most often To. it is shown in similarity of a shape of a body, bodies of the movement, sense bodys and other so-called ektosomatichesky bodies. It is characteristic that To. it is observed at the organisms very far from each other by origin. In the presence To. separate bodies other signs (structures, bodies) keep the initial distinction which is constantly maintained by divergent evolution (see. Divergence ).

A classical example To. similarity of a shape of a body and fins of the died-out ichthyosaurus and modern shark or dolphin is. These animals have the general (water) habitat and are adapted for bystry movement in it. At the same time on the internal organization, ways of reproduction and other signs they are various.

Convergent property is inherent also in representatives of flora.

See also Theory of evolution .

Bibliography: Mayr E. Populations, types and evolution, the lane with English, page 403, M., 1974, bibliogr.; Shmalgauzen I. I. Problem of Darwinism, page 393, L., 1969.

V. N. Pavlova.