Meeting Abstract

P1.106  Wednesday, Jan. 4  Phylogenetics, Morphometrics and Biomechanics of Reef Fishes WESTNEAT, M. W.*; MCCORD, C. M.; Field Museum of Natural History; University of Chicago mwestneat@fieldmuseum.org

Fishes use a sensational diversity of jaw mechanisms to capture and process their food. One of the hallmarks of this diversity is the complexity of the kinetic fish skull, which can have more than 20 mobile skeletal elements driven by numerous muscles. This complexity has often led to compelling examples of both divergence in form and function, as well as convergence in design and behavior. The integration of biomechanical modeling, geometric morphometrics and phylogenetic analysis is critical to addressing questions of functional evolution, biomechanical convergence, and radiation in diverse clades. Here we present detailed morphometric analysis of the skull in two diverse reef fish families; the Labridae (the wrasses) and the Balistidae (the triggerfishes). Procrustes geometric and standard morphometric analysis were performed on a set of 20-32 landmark coordinates summarizing the shape and key functional elements of the skull. Morphospace plots of phylogenetically independent contrasts reveal cranial shape-based clustering patterns that largely mirror higher-level phylogenetic groupings. However, frequent convergences in cranial shape across phylogenetic groupings are also identified. New software for analysis of cranial levers and linkages allows for simulation of structure-function relationships in a wide range of taxa, using the same coordinate data sets employed for morphometric tests. Linkage modeling leads to several conclusions regarding the evolution of function in reef fishes: (1) Coordinate based shape analyses can yield functional insight using mechanically relevant landmarks; (2) Novel biting mechanisms in triggerfishes and wrasses are associated with novel morphospace occupation; (3) Multiple mechanical variables and levels of design should be considered when defining convergent biomechanical systems. Funded by NSF DEB-0844745, NSF DGE-0903637 and an NSF EAPSI Fellowship 2011.