Two congeneric species of Japanese field mice, Apodemus speciosus and Apodemus argenteus, differ considerably in their feeding strategies and habitat utilizations. Although both species are omnivorous, previous studies demonstrated that A. argenteus typically eats a wide variety of food items than A. speciosus. Moreover, A. speciosus is a ground dweller, while A. argenteus commonly shows arboreal movements. These dietary and lifestyle differences suggest potential disparity in morphological structure. In this study, we used geometric morphometrics to examine the skull shape differences are related to their feeding strategies and habitat preferences. We found that A. argenteus showed wider zygomatic arches and a broader mandibular ramus. These traits are linked to enlargement of the attachment sites for the masticatory muscles. We also found a relatively short mandibular diastema in A. argenteus, which may increase the mechanical advantage of the lower jaw by reducing the out-lever arm. These results suggest that A. argenteus has a greater relative bite force that is suitable for diversified diets as a more generalist feeder. Interspecific differences in the upper incisor, inter-orbital width, and auditory bullae might be associated with the lifestyles of these two species. Additionally, the presence of two distinct modules in the cranium (rostrum and braincase) and mandible (ascending ramus and alveolar region) may reflect similar patterns of intraspecific variation within both species. In conclusion, skull shape enables distinction between these two species and may favor adaptation to their ecology and lifestyle, despite the similarities in craniomandibular modules associated with common developmental factors.

日本田鼠的两个同类物种，姬鼠和姬鼠在喂养策略和栖息地利用方面存在很大差异。虽然这两个物种是杂食性的，以前的研究表明A. argenteus通常吃各种各样的食物比项目A. speciosus。此外，A。speciosus是地面居民，而A. argenteus通常显示树栖运动。这些饮食和生活方式的差异暗示了形态结构上的潜在差异。在这项研究中，我们使用几何形态计量学检查了头骨的形状差异与它们的饲养策略和栖息地偏好有关。我们发现阿根廷曲霉显示较宽的弓和较宽的下颌支。这些特征与咀嚼肌附着部位的扩大有关。我们还发现了银色短man的下颌舒张期相对较短，这可能通过减少杠杆臂来增加下颌的机械优势。这些结果表明，A。argenteus具有更大的相对咬合力，适合作为多种饮食的多样化饮食。上切牙，眶间宽度和听性大疱的种间差异可能与这两个物种的生活方式有关。此外，颅骨（rostrum和脑箱）和下颌骨（升支支和齿槽区域）中两个不同模块的存在可能反映了两个物种内种内变异的相似模式。总之，尽管颅下颌模块与常见的发育因素相关，但头骨的形状使这两个物种得以区分，并可能有利于适应它们的生态和生活方式。