PRF/J: Craniofacial Integration in Growth and Phylogeny: Analysis by Principal Warps

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Morphological integration can be defined as a characteristic of a transformation that deforms one morphology into another. A region of morphology is integrated if the deformation acts globally; regions are poorly integrated if they comprise parts that undergo different transformations. The goals of this postdoctoral project are to: (1) identify integrated parts of the skull and jaw of species of New World murid rodents; (2) compare parts detected by morphometric analysis to those predicted by developmental theory and functional morphology; and (3) explore if developmentally integrated units remain integrated through phylogeny. Known-age tissue samples of the cotton rat, Sigmodon fulviventer, will be explored for ontogenetic integration; adult samples of S. fulviventer, S. hispidus berlandieri, S. hispidus komareki, Neotoma floridana, Peromyscus leucopus and P. maniculatus will be analyzed for phylogenetic integration. Changes in shape coordinates will be used to analyze transformations within and between regions of the skull and jaw hypothesized a priori to be integrated because of developmental origin or function. The uniform, global but not uniform, and localized non-linearities will all be analyzed. The hierarchy of integrated parts will be constructed by application of the method of principal warps which decomposes non-global components hierarchically as determined by the amount of "bending energy" required to displace the landmarks, regardless of the affine transformation. The principal warps can be used to categorize the features of shape change, each at its own geometric scale, and to investigate variation in the underlying bending-energy at progressively larger geometric scales. This one-year fellowship activity will take place at the University of Michigan.