Functional Versus Morphological Diversity in Macroevolution

Studies of the evolution of phenotypic diversity have gained momentum among neontologists interested in the uneven distribution of diversity across the tree of life. Potential morphological diversity in a lineage is a function of the number of independent parameters required to describe the form, and innovations such as structural duplication and functional decoupling can enhance the potential for diversity in a given clade. The functional properties of organisms are determined by underlying parts, but any property that is determined by three or more parts expresses many-to-one mapping of form to function, in which many morphologies will have the same functional property. This ubiquitous feature of organismal design results in surfaces of morphological variation that are neutral with respect to the functional property, and enhances the potential for simultaneously optimizing two or more functions of the system.