Morphological modularity and assessment of developmental processes within the vole dental row (Microtus arvalis, Arvicolinae, Rodentia)

Knowledge of mammalian tooth formation is increasing, through numerous genetic and developmental studies. The prevalence of teeth in fossil remains has led to an intensive description of evolutionary patterns within and among lineages based on tooth morphology. The extent to which developmental processes have influenced tooth morphologies and therefore the role of these processes in these evolutionary patterns are nonetheless challenging. Recent methodological advances have been proposed allowing the inference of developmental processes from adult morphologies and the characterization of the degree of developmental integration/modularity of morphological traits by studying the patterns of variation within and among individuals. This study focuses on the geometric shape of the lower molars of the vole species Microtus arvalis. Our results suggest (i) quasi-independence of each molar at the developmental level (developmental modules), even slightly stronger for the third molar supporting some genetic and developmental hypotheses and (ii) more pervasive integration processes among molars at the morphological level. © 2009 Wiley Periodicals, Inc.