Experiment and comprehending the evolution of function

Abstract

Experimentation involves the manipulation of variables in vertebrate form-functionsystems. Two general experimental approaches are used most often in attempts at defining the relationship of form and function in animals: holding the form constant while varying the experimental regime, and the reverse. Either real or abstract forms and experimental regimes canbe productive, though all variations have limitations. The place of such experiments in the understanding of the evolution of form-function is explored in a narrative tracing the change in our conception of function and evolution for the tetrapod ear over the past twenty years. Combining experimental functional anatomy and studies of structural evolution and phylogeny creates an environment of reciprocal illumination. The experimental determination of function illuminates details of structure otherwise not noticed-creating new characters or suggesting reinterpretations for those already known. Attempts to understand the evolution of structure and function in a clade can suggest experiments or key taxa for experimental study. This combinedapproach is relatively new and is being led by vertebrate morphologists. © 1991 by the American Society of Zoologists.