NEW DIRECTIONS IN COMPARATIVE PHYSIOLOGY AND BIOCHEMISTRY - MECHANISMS, ADAPTATIONS, AND EVOLUTION

Historically, the discipline of comparative physiology and biochemistr y has had two major goals: (1) elucidation of mechanisms and their ada ptative significance, and (2) understanding of the evolution of mechan isms and adaptations. In general, the first goal has dominated the fie ld. In a mechanistic/adaptational approach, the diversity of organisms is an experimental parameter in the investigation. Lineage-specific c haracteristics reveal both how physiological systems work and how diff erent kinds of animals are adapted to different kinds of environments. We believe that this approach is far from outdated, in part because m any animal groups have been investigated superficially if at all, and in part because the incorporation of fundamentally new technologies in to our discipline permits us to address previously intractable questio ns about even intensively studied animal groups. In evolutionary physi ology and biochemistry, the diversity of lineage-specific physiologica l systems and how they came to be is the subject of investigation. Ear ly attempts to employ the evolutionary approach were not only few in n umber, they were unsatisfying in outcome because neither phylogenetic nor mechanistic/adaptational knowledge was adequate to serve as a firm foundation. We agree with earlier authors that new and more sophistic ated applications of this approach, together with progress in understa nding both animal phylogeny and mechanisms/adaptations, all promise to allow us at last to fulfill our second historic goal. In our view, an integration of the two approaches seems to present the most productiv e trajectory into the next century.