Meeting Abstract

36.1  Jan. 5  Ubiquity of many-to-one mapping in functional traits: examples and evolutionary implications ALFARO, ME*; COLLAR, DC; WAINWRIGHT, PC; Washington State University; University of California, Davis; University of California, Davis alfaro@wsu.edu

Many functional traits can be decomposed into the emergent functional property and its underlying parts. For example, maximum bite force is determined by the product of two morphological parameters: the area of the physiological cross section of the jaw closing muscles, and the mechanical advantage of the lower jaw. In this model, identical bite forces can be attained by two distinct combinations: one in which the jaw adductor is relatively large and the mechanical advantage small and another in which the adductor is small and the mechanical advantage large. We use the term many-to-one mapping to describe this intrinsic redundancy between trait form and function. To examine how pervasive this property is in complex systems, we considered a diversity of functional traits from recent comparative studies and measured the degree of morphological redundancy present in the empirical data sets. We also used computer simulation to generate theoretical distributions of the number of morphological solutions over a range of biologically relevant functional values. Our findings indicate that 1) morphological redundancy is empirically widespread and, 2) it is generally true that there are far fewer solutions to extreme values of functional properties than moderate values. We suggest that many-to-one mapping is of special significance to the study of organismal diversification because of its potential to partly decouple morphological and functional evolution and because intrinsic form-function relationships may influence the outcome of morphological convergence in the face of similar selective pressures. For these reasons, we suggest that many-to-one mapping is a major principle of organismal design.