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a group of organisms, part of a local population, which have the same genotype and are similar in practically all respects. The Danish biologist W. Johannsen (1909) considered the homozygotic biotype in self-pollinating plants to be the most elementary structural unit of a population. The Soviet botanist V. N. Sukachev (1927, 1935) called clones of plants that were derived by numerous root grafts of the plant or by division of a single bush “biotypes.” In populations of cross-pollinated species, biotypes can be distinguished both as successive selection with isolation of the offspring and as manyfold multiplication in close degrees of relation (inbreeding). In the 1920’s and 1930’s many biologists (the Swedish botanist G. Turesson; the Soviet biologists N. I. Vavilov, M. A. Rozanova, and others) considered biotypes to be the smallest taxonomical unit. Species, in their opinion, arose from combination of biotypes as a result of recombination and selection.
Large groups of organisms, often consisting of many species and characterized by similar adaptation to the exploitation of definite habitation conditions, are also called biological types or life forms. In this sense, for example, the group of underground burrowing rodents, the group of ephemeral desert plants, and so on are taken to be biological types.
REFERENCESBerman, Z. I., K. M. Zavadskii, A. L. Zelikman, et al. Sovremennye problemy evoliutsionnoi teorii. Leningrad, 1967.
Zavadskii, K. M. Vid i vidoobrazovanie. Leningrad, 1968.
K. M. ZAVADSKII