Unity in diversity: a perspective on the methods, contributions, and future of comparative physiology.

This brief essay on the methods, objectives, achievements, and future promise of the discipline known as comparative physiology focuses on three principle issues. First, how is this discipline defined in terms of its approaches and goals? What does the adjective comparative denote, and what makes the comparative approach unique? Second, what are illustrative examples of the successes of the comparative method in the study of physiology? Why has the comparative approach so often been critical in the development of basic understanding of physiological systems? Third, how is comparative physiology likely to contribute in the near future to the biological sciences, here broadly defined to include research ranging from study of the consequences of global change to the development of biomedical technology? And, conversely, how are advances in other disciplines in biology likely to enhance comparative physiology? I hope to demonstrate that comparative physiology is an essential complement to other disciplines within physiology that commonly exploit a relatively small number of so-called model organisms in attempts to elucidate basic mechanisms of physiological function. I argue that there exists a creative interplay between physiologists doing comparative work and others who carry out primarily reductionist studies with model species. Whereas the latter types of studies offer the comparative physiologist many useful new techniques and insights into basic mechanisms, it is the comparative physiologist who often uncovers important new phenomena for investigation and who, through the logic of comparative analysis, elucidates key principles that might not emerge from the study of conventional model organisms.