Meeting Abstract
43.4 Sunday, Jan. 5 11:00 Variable diets affect mammalian mandibular development differently than stable diets with mechanically resistant properties MENEGAZ, RA*; SZCZODROSKI, AF; ROLD, TL; HOFFMAN, TJ; RAVOSA, MJ; Brown Univ.; Truman Mem. VA Hosp.; Truman Mem. VA Hosp.; Truman Mem. VA Hosp.; Notre Dame rachel_a_menegaz@brown.edu
The diets of juvenile mammals are known to affect the morphology of the adult masticatory apparatus. Increased loading from mechanically resistant food items has been shown to influence the morphology of the mandible and its joints, the maxilla, and the muscle attachment sites in the skull. However, much of the current knowledge is derived from juveniles fed a non-variable diet for the duration of their postweaning growth period. Thus, it remains unclear how ontogenetic variation in diet, as may occur in seasonal habitats, affects the resulting adult morphology. To address this gap, we raised four dietary cohorts (n=10/cohort) of Sprague-Dawley rat from weaning to skeletal maturity. Two cohorts were fed a stable diet of either solid or powdered pellets. The other two cohorts were fed a variable diet consisting of either solid/powdered pellets for the first half of the study, followed by a shift to the opposite diet. Morphometric analyses indicate that a dietary signal is most apparent in the mandibular ramus of older subadult rats, whereas variation in mandibular morphology of younger juveniles is concentrated in the mandibular corpus and is related to dental development. Furthermore, adult morphology is correlated with the ontogenetic timing of the consumption of a mechanically resistant diet. The CMJ and coronoid process are influenced by the early postweaning diet, whereas ramus size and angular process morphology are related to the diet consumed later in the growth period. This research highlights the importance of more naturalistic models of mammalian feeding, and has ecomorphological implications for wild and fossil taxa with seasonal or temporally variable diets.
