Meeting Abstract

P1.47  Sunday, Jan. 4  Gape and bite force in the northern grasshopper mouse (Onychomys leucogaster) and the deer mouse (Peromyscus maniculatus) PEIFFER, E.K.*; FORD, S.; WILLIAMS, S.H.; Ohio University; Ohio University; Ohio University willias7@ohio.edu

Previous studies on the masticatory apparatus of the northern grasshopper mouse (O. leucogaster) and the deer mouse (P. maniculatus) suggest that there are architectural differences in the jaw muscles relating to feeding behavior and diet. For example, for some of the jaw-closing muscles, O. leucogaster may have a smaller physiological cross-sectional area (PCSA) but a more favorable lever advantage for producing bite force at the incisors than P. maniculatus. This configuration is thought to help maintain or increase bite force capabilities at large gapes in O. leucogaster, which may be required to facilitate their carnivorous diet consisting of similar-sized vertebrates. To determine the relationship between gape and bite force in both species, we collected bite forces at different gapes from 8 individuals of P. maniculatus and 11 individuals of O. leucogaster using an adjustable bite force transducer instrumented with strain gauges. Despite the fact that O. leucogaster weighs almost twice as much as P. maniculatus, both species prefer to bite at a similar range of gapes, from 4.0 mm to 8.0 mm, significantly lower than their maximum gapes. Moreover, absolute and relative maximum bite forces in both species peak at 5.0 mm of gape. However, as expected O. leucogaster has absolutely and relatively higher maximum bite forces at each gape. Any structural differences in the jaw musculature appear to have a negligible influence on producing significantly larger gapes, but may facilitate the larger bite forces in O. leucogaster.