关键词: 社鼠, 种群, 头骨, 形态特征, 地理分化

Abstract: Population divergence is a crucial step in speciation,and studies on patterns of intraspecific variation based on
morphological traits can be helpful to uncover and further understand microevolutionary processes. In this research,we made a comprehensive comparison on skulls of Chinese white-bellied rat (Niviventer confucianus)populations among five mountains in middle and western China. The results indicated that skull variables among these populations are significantly different. In addition,discriminant function analyses further uncovered that Chinese white-bellied rat populations in the Qinling Mountains and Sichuan mountains have diverged completely in their skull morphology. Except for those between the Qionglai and Xiangling populations,skulls between the rest of the populations in Sichuan have diverged significantly,as well 69.1% of skulls were correctly classified to their source mountains,and variables including median palatal length and upper diastema length contributed most to their divergence,implying that the divergence in skulls morphology among the five populations perhaps primarily resulted from their food habits. Our results also illustrate that more caution should be taken to establish and discriminate intra-specific taxonomy units (such as subspecies)for small mammals which occupy a large geographical range.

Key words: Geographical divergence, Morphological trait, Population, Skull, White-bellied rat (Niviventer confucianus)