Meeting Abstract

89.4  Friday, Jan. 6  Diet-Based Biomechanical Plasticity in Mouse Mandibles ANDERSON, P*; RAYFIELD, EJ; RENAUD, S; Univ. Bristol, UK; Univ. Bristol, UK; Univ. Lyon, France phil.anderson@bristol.ac.uk

The functional consequences of morphological variation is a major field of inquiry in modern biology. The relationship between form and function can be complex, and this is especially true in situations of phenotypic plasticity, where morphology is altered during development based on environmental stresses. Do environmental pressures (such as mechanical loading related to diet) affect morphology through bone remodeling in a functionally adaptable manner? We utilize a data set of lab mice, reared on mechanically distinct diets to test hypotheses related to morphological plasticity and its effects on mechanical function. We used 39 3-week old female mice from inbred strain C56BL/6J. Twenty of the mice were raised on a soft food diet and 19 on a hard food diet. We used morphometric analyses to compare the general shape between dietary groups using both left and right mandibles. We measured four different mechanical advantage metrics from each mandible based on the masseter and temporalis muscles and bite points on the incisors and molars. Landmark based morphometrics show significant difference in shape between mice raised on hard food and soft food diets. However, there are also significant differences between right and left mandibles across dietary groups, indicating potential directional asymmetry within these mice. Functional analyses based on lever mechanics illustrate that these shape differences have functional consequences. Hard food eaters have higher mechanical advantage measures than soft food eaters when left mandibles are compared. Differences are more limited when regarding right mandibles. Hence, there are strong mechanical signals in the phenotypic plasticity of mice raised on diets with different mechanical requirements.