Meeting Abstract

78.4  Sunday, Jan. 6  How do triggerfish eat? The evolution of variable feeding behavior in balistid fishes BUXMAN, C.L.*; WESTNEAT, M.W.; University of Chicago; Field Museum of Natural History cmccord@uchicago.edu

Muscles in many vertebrates have become repeatedly subdivided, yielding multiple actuators for biomechanical systems. Muscle subdivisions may, with evolutionary change in origin, insertion, or contractile physiology, increase the potential range of behavioral repertoires. The highly subdivided adductor mandibulae muscles of triggerfishes (Teleostei: Balistidae) are an ideal system for investigating the functional significance of a subdivided musculature. Here, we investigated the behavioral consequences of multiply subdivided jaw closing muscles through a series of feeding experiments. Feeding sequences from several morphologically and phylogenetically disparate species were filmed during bouts with different prey items of dissimilar material properties. Video sequences were digitized using 14 landmarks to assess the biomechanically relevant kinematics of the cranium. Kinematic variables were calculated from landmark data, phylogenetically corrected, statistically analyzed and compared across treatments and taxa, and mapped onto the balistid phylogeny in order to identify potential patterns of evolutionary change in feeding behavior. Our results indicate that triggerfishes modulate feeding behavior (low stereotypy and high flexibility). Furthermore, variation in kinematic profiles is only somewhat consistent with phylogenetic disparity. Taken together, our results suggest multiple independent origins of feeding behavior strategies in the triggerfish lineage. Future work will add in vitro and in vivo muscle properties, and several measures of triggerfish jaw performance that, along with the behavioral analyses discussed here, will provide insight into the evolutionary relationship of form and function in this group. Supported by NSF IGERT No. DGE-0903637 and DEB- 0844745.