Abstract: To investigate geographical variation in skull morphology of the long-tailed dwarf hamster (Cricetulus longicaudatus) across Shanxi Province, specimens from 11 regions were analyzed using landmark-based geometric morphometrics. After digitization and removal of non-shape variation, principal component analysis (PCA), thin-plate spline (TPS) analysis, and multidimensional scaling (MDS) were applied. While PCA did not show clear geographical clustering, thin-plate spline analysis revealed localized shape changes in structures such as the auditory bulla, zygomatic arch, and maxillary tooth row. MDS further indicated that skull shape variation was significantly associated with longitude, altitude, and annual precipitation. These results suggested adaptive divergence in skull morphology among populations in response to environmental gradients, providing insights into ecological adaptation and evolutionary dynamics in rodents.

Key words: Cricetulus longicaudatus, skull geometric morphometrics, principal component analysis, thin-plate spline analysis, multidimensional scaling