Quantifying the link between craniodental morphology and diet in the Soricidae using geometric morphometrics

Abstract

Abstract Dietary adaptations have often been associated with heightened taxonomic diversity. Yet, one of the most species-rich mammalian families, the Soricidae, is often considered to be ecologically and morphologically relatively homogenous. Here, we use geometric morphometrics to capture skull and dentary morphology in a broad sample of shrew species and test the hypothesis that morphological variation among shrew species reflects adaptations to food hardness. Our analyses demonstrate that morphology is associated with dietary ecology. Species that consume hard food items are larger and have specific morphological adaptions including an anteroposteriorly expanded parietal, an anteroposteriorly short and dorsoventrally tall rostrum, a mediolaterally wide palate, buccolingually wide cheek teeth, a large coronoid process and a dorsoventrally short jaw joint. The masseter muscle does not appear to play an important role in the strong bite force of shrews and the dentary is a better indicator of ecology than the skull. Our phylogenetic flexible discriminant function analysis suggests that the evolutionary history of shrews has shaped their morphology, canalizing dietary adaptations and enabling functional equivalence whereby different morphologies achieve similar dietary performances. Our work makes possible future studies of niche partitioning among sympatric species as well as the investigation of the diet of extinct soricids.