FEEDING, FUNCTION, AND PHYLOGENY - ANALYSIS OF HISTORICAL BIOMECHANICS IN LABRID FISHES USING COMPARATIVE METHODS

Recently developed methods in phylogenetic systematics enable the disc overy of associations among diverse characters of organisms such as mo rphology, biomechanics, and ecology among clades. In this study, the r esults of multiple character correlation techniques were compared usin g a data set on the functional morphology and ecology of feeding in th e 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 d epression mechanisms, analysis of morphometric variation in the trophi c apparatus, and description of the natural diet of labrids. Analysis of phylogenetic association between dietary and biomechanical characte rs within the phylogeny was performed using character optimization to map characters onto the phylogeny. Statistical tests of association be tween pairs of discrete characters involved contingent states tests an d concentrated changes tests. Phylogenetic correlations between contin uous quantitative characters were determined using the methods of squa red-change parsimony, independent contrasts, and phylogenetic autocorr elation. A diversity of techniques yielded similar answers in this eas e study, suggesting that evolution of dietary habits and feeding behav ior is tightly linked to the biomechanics of the feeding apparatus.