ABSTRACT
The environment of living organisms is represented fay a set of external ecological factors which the organism perceives and by which it is affected. If necessary, i.e., if the organism is motivated, it can respond to these factors. This necessity (motivation) is determined by the intrinsic state of the organism. The relationships between the environment and the organism are determined by the genetic program of the given species and by individually acquired experience. The proportion between these two components varies. When the animal is short lived, when it does not encounter its parents from which it could take experience, and when it lives in a small territory and in an only slightly changing environment, then it reacts mostly instinctively. On the other hand, when the animal has a long life span, when it develops slowly even after birth (hatching), it is subject to parental care and gradually acquires its own individual experience, and consequently, its reactions are a combination of the inborn and the learned. The organism thus becomes adapted to the environment. In biological literature the term adaptation is used to denote a change in the structure and function of the organism and its behavior. It is a result of an evolutionary process of the given species which is genetically encoded. It is species specific, irreversible, and encompasses the whole species. Every species has a typical way of obtaining food, its consumption, and excretion; equally species specific are such features as locomotion, protection against predators, relations with the members of the same species and other species, sexual and parental behavior, exploration, marking the territory, biological rhythms, etc. In another meaning the term adaptation denotes changes that are short term, arise at any age, are not species specific but individual specific, are reversible, and are not directly genetically encoded. They reflect the relationship of the individual to the momentary state of the environment. This process is a physiological adaptation known also as adjustment. A typical example is acclimation during which a change in one or more environmental stimulus elicits in the organism a change in homeostatic systems. During evolution, higher animals developed a relative independence of the organism from environment, which is ensured homeostatically. As a consequence, the organism acquired a higher variability of functions which allows it to maintain its stability in a wide range of environmental influences. 1
