Adaptations

Abstract

Adaptations are defined for our purpose as character combinations, metabolic processes, and developmental pathways that enable an organism to survive in a given niche; and to occupy an optimal position in relation to the specific physiological possibilities set by its evolutionary history. Every adaptation then reflects characteristics of the niche. Now part of this complex are genetic adaptations of populations to environmental heterogeneity, which will be discussed in Chapter IV under the heading “Adaptive Strategies.” Adaptive strategies often lead to the development of polymorphic populations. The adaptive value of these populations over all niches of the heterogeneous environment consists in being the source of a variety of phenotypes adapted to certain niches, not of an optimum phenotype for all niches. Thus, adaptations, in the sense of this chapter, are concerned only with “pure” and not with “mixed” strategies. The evolutionary possibilities of a population are set in each case by past experience stored as genetic information and by the value of this past experience under the special conditions of a given niche. Genetic information is modified through reactions to selection in the course of generations. Existing adaptations may be improved and new adaptations may be developed.