The renin-angiotensin system and the mechanisms regulating this system developed during the adaptive evolution of verte brates, along with many other systems involved in the in tegrated survival of the organism. Because animal species have evolved from common ancestral populations, a basis for the comparison of body structures and physiological processes ex ists among animal groups belonging to different classifications. The comparative approach provides a better understanding of the structure and function of adaptive systems and facilitates the development of general principles governing...