© 1980 by The Society for Integrative and Comparative Biology
The Definition and Recognition of Biological Adaptation1
Department of Biological Sciences, Columbia University New York, New York 10027
Biological adaptation is a property of phenotypic features of organisms relative to selection demands of the environment. Adaptive features are ones having properties of form and function which permit the organism to maintain successfully the synerg between a biological role of that feature and a stated selection force. The degree of goodness of the adaptation can be measured by means of the amount of energy needed to maintain the synerg with less energy indicating better adaptation. Adaptation does not apply to a close fit between different features or between the form and function of a feature or to the mutual interactions between features of a structural network. The state of being adapted is independent of the process of becoming adapted as adaptations need not evolve under the control of selection forces to which they are now adapted. Selection is here considered as the demands placed on the organism by the environment with which the organism must cope to continue surviving as an individual. Adapted features have been judged using three methods—the comparative the correlative and the synthetic—of which only the last is valid. The synthetic method requires study of the forms and functions of the feature in the laboratory and of the biological roles of the feature and the selection demands of the environment in the field. It is suggested that the best approach for the study of adaptations is a team effort with constant feedback between the laboratory and field phases of study. It is urged that attention be given to the development of an ecological morphology to supplement functional morphology and provide the necessary foundation for proper elucidation of biological adaptations.