Meeting Abstract

83.2  Tuesday, Jan. 6  Trapezoids and tongues: the evolution of prey-processing mechanics in teleost fish CAMP, A.L.*; KONOW, N.; SANFORD, C.P.; Hofstra University; Johns Hopkins Medical Institute; Hofstra University acamp1@pride.hofstra.edu

Mechanical models aid evolutionary analyses of complex biological systems by permitting quantitative comparisons between species and lineages. The independent origin of raking, a novel prey-processing behavior using the tongue-bite apparatus (TBA), in two lineages of teleost fishes (salmonids and osteoglossomophs) provides a model system in which to examine the relationship between structure and function in evolution. Salmonids exhibit a pronounced degree of similarity in morphology, muscle-activity and kinematics, while osteoglossomorphs display structurally and functionally diverse TBAs and raking behaviors. Using a planar 4-bar linkage to model raking mechanics, the functional consequences of structural differences on output motion were directly related to the degree of behavioral stereotypy or diversity within and between lineages. Additionally, force and velocity trade-offs, as predicted by the 4-bar configuration and existing kinematic data, were examined in several lineage-representatives. Salmonids are united by a specialized 4-bar configuration which enables optimized raking, but the unique functional properties of this system are easily compromised by even slight structural changes. In contrast, osteoglossomophs have 4-bar architecture that is modifiable via relatively minor structural changes, without loss of function, to prioritize either force or velocity-output. We show that 4-bar mechanisms provide useful models for interspecific comparisons in an evolutionary context and may explain the unprecedented degree of stereotypy among the trophic generalist salmonids. Supported by the NSF (IOS#0444891, DBI#420440).