Ecological and functional correlates of molar shape variation in European populations of Arvicola (Arvicolinae, Rodentia)

Lower first molar shape in Arvicola spp. at European level has been studied by means of Geometric Morphometrics. We took into account bioclimatic variables, size, lifestyle and phylogenetic relationships. We used Partial Least Squares and Phylogenetic Independent Contrasts in order to assess which factor affects the most molar shape morphology. Once the phylogenetic history was taken into account, climate resulted the most influencing factor in explaining molar morphology, followed by size. Molar shape is not related to lifestyle. Molar shape and size, even if different among species, are not phylogenetically structured. On the opposite, lifestyle depends on the phylogeny, and size and lifestyle are significantly related even considering phylogenetic relationships. Fossorial forms are significantly smaller than semi-aquatic ones, suggesting that they are less subjected to predator pressure of semi-aquatic species and that the two lifestyles are characterized by different allometric patterns.