Adaptive Zone

the complex of environmental conditions determining the type of adaptations of a given group of organisms. The term was originated by the English biologist G. G. Simpson in 1944. Adaptive zones are divided into subzones corresponding to the more particular specific conditions of existence. The entire organic world may be regarded as a system of broad or narrow adaptive zones which are limited by the ties which their inhabiting organisms have with environmental conditions and are similar in basic characteristics for ecologically close forms (“dog zone,” “cat zone,” “fern zone,” and so on). Adaptive zones may be occupied by systematically remote species—marsupial wolves, for example, belong to the adaptive zone of the dog; the liana zone includes hops, the grape, the kidney bean, and the honeysuckle; and so forth. Adaptive zones change constantly as a result of variation in physical and geographic conditions and the evolution of organisms living in a given zone. A saber-toothed tiger sub-zone, for example, probably never existed until the evolution of herbivorous animals made specialization of the tiger critical for survival; the extinction of the large herbivores brought with it the elimination of this adaptive subzone.