Integration Patterns of Molar Tooth Rows in the Extant Voles (Mammalia: Arvicolnae): Geometric Morphometric Analysis at a Macrolevel

An exploration of the integration pattern of cheek teeth in Arvicolinae was conducted based on the sample representing 40 Recent genera/subgenera of voles. It employed the analysis of Pearson's correlations between dental units (entire crown outlines and individuated crown elements) described by geometric morphometric methods, and its results were interpreted as phyletic coordinations (in the sense of Schmalhausen). The lower tooth row was shown to be integrated somewhat weaker as compared to the upper one. The upper and lower tooth rows were in general the least intercorrelated, but M3 and m1 were rather highly correlated. Regarding intra-dental correlations of particular teeth, the least innerly integrated were m2 and m1. Each molar was shown to be subdivided, with some variants, into anterior and posterior portions. The lingual crown elements tended to be a little more correlated than the labial ones, while correlations between contralateral elements were the weakest. One of the most peculiar features of intra-dental correlations was shown to be the strong intercorrelations of all elements of m1 anteroconid that made it an autonomous unit within the lower toothrow. Regarding inter-dental correlations of crown elements, those between homologues were on average higher as compared to non-homologues. This feature of the overall integration pattern of the phyletic coordinations in arvicoline molars agreed in general with that shown previously for the ontogenetic correlations of cheek teeth in some unrelated mammals. Correlations between molar outlines themselves and phylogenetically independent contrasts calculated for the 1st MDS axis extracted from those outlines were shown to agree in some important details, with the former being on average weaker than the latter.