Feeding, Function, and Phylogeny: Analysis of Historical Biomechanics in Labrid Fishes Using Comparative Methods

Abstract

Recently developed methods in phylogenetic systematics enable the discovery of as? sociations among diverse characters of organisms such as morphology, biomechanics, and ecology among clades. In this study, the results of multiple character correlation techniques were compared using a data set on the functional morphology and ecology of feeding in the Cheilinini and outgroups (Perciformes: Labridae). The following two questions were addressed: What are the patterns of evolutionary change in structure and function of the feeding mechanisms of labrid fishes? Are evolutionary changes in trophic structure, feeding biomechanics, and feeding ecology congruent at different levels of labrid phylogeny? This study integrated previous work on the phylogenetic relationships of labrid fishes, quantitative modeling of jaw protrusion and hyoid depression mechanisms, analysis of morphometric variation in the trophic apparatus, and descrip? tion of the natural diet of labrids. Analysis of phylogenetic association between dietary and bio- mechanical characters within the phylogeny was performed using character optimization to map characters onto the phylogeny. Statistical tests of association between pairs of discrete characters involved contingent states tests and concentrated changes tests. Phylogenetic correlations between continuous quantitative characters were determined using the methods of squared-change parsi? mony, independent contrasts, and phylogenetic autocorrelation. A diversity of techniques yielded similar answers in this case study, suggesting that evolution of dietary habits and feeding behavior is tightly linked to the biomechanics of the feeding apparatus. (Functional morphology; system? atics; ecology; character correlation; comparative methods; phylogeny; Labridae.)