WAINWRIGHT, P.C.; Univ. of California, Davis: Making diversity: the evolution of feeding mechanics in fishes

Biological diversity is not only about the number of taxa on earth, but also their morphological and functional diversity. My research program is aimed at understanding how functional diversity arises through studies of the feeding mechanism of fishes. We have found that the remarkable mechanical diversity in fish feeding systems comes about most often through changes in the properties of muscles and the skeletal linkage systems that transmit muscle action into jaw motion. Our recent work on the diversity of jaw linkage mechanics in labrid fishes (wrasses, parrotfish and their kin) using empirical data, mechanical models and simulations of evolution, illustrates what may be two general properties of the origins of high diversity in complex functional systems. First, in many cases a particular functional property can be created by multiple morphologies. Many-to-one mapping provides a mechanism for generating considerable morphological diversity even if lineages are evolving toward distinct adaptive peaks, because selection for a given property can lead to several alternative morphological solutions. To understand how the spectacular functional diversity of labrid fishes has come about we analyzed the degree to which there has been correlated evolution among nine mechanical properties of the feeding mechanism in 60 labrid fish species. The most striking result from these analyses is that correlations between traits are low (correlations between phylogenetically independent contrasts). In contrast to the traditional view of evolution of suites of traits, we find that many mechanical properties of the labrid feeding apparatus are not constrained to evolve in concert and this independence has allowed labrids to evolve a remarkable range of mechanical combinations in their feeding mechanisms. Supported by NSF IBN0076436.