Meeting Abstract

69.5  Sunday, Jan. 6  Modularity of the rodent mandible. Integrating teeth, muscles and bone ZELDITCH, M.L.*; WOOD, A.R.; BONETT, R.; SWIDERSKI, D.L.; U. Michigan, Ann Arbor; U. Michigan, Ann Arbor; U. Tulsa, OK; U. Michigan, Ann Arbor zelditch@umich.edu

The rodent mandible is a favored model system for studies of modularity because it forms from developmental modules that must be tightly regulated, both temporally and spatially, to produce a functioning whole. Additionally, these mandibular modules must be coordinated with developing muscles, a coordination that likely arises early in development but which regulates mandibular morphogenesis later. Whether musculoskeletal interactions integrate or modularize the jaw is an open question. According to some models, they integrate the ascending ramus but others propose that they integrate individual processes or regions loaded by the same muscle. All available models agree, however, that the alveolar region is unaffected by muscles and the ascending ramus is unaffected by teeth. To test for mandibular modules, we sampled landmarks plus semilandmarks selected to capture information about curvature on jaws of adult deer mice (Peromyscus maniculatus bairdii). We examined correlated fluctuating asymmetries because correlations resulting from random perturbations arguably arise from direct epigenetic interactions such as signaling. Preliminary results show a complex structure of integration between the two purported modules: the molar alveolus is as highly correlated with the shape of the angular and part of the condyloid as it is with the incisor alveolus. Moreover, the angular is as highly correlated with the incisor as it is with the condyloid although the condyloid is not correlated with the incisor. Our results thus indicate a complex pattern of integration between teeth, muscles and bone as well as a structure better represented by a network than a nested hierarchy or semi-autonomous modules.