RNase5是RNASE A基因超家族中的一个重要成员，是分子进化研究的理想模型之一。基于基因组水平，我们对啮齿目的3个进化枝10科17个物种开展RNase5的分子进化研究。利用TBlastN及BlastN方法鉴定每个基因组的RNase5基因，发现该基因在啮齿目的Ctenohystrica所有物种发生丢失，时间是在Ctenohystrica形成之后；邻接法和最大似然法构建的系统发育树均支持RNase5在“与小家鼠相关的进化枝”的小家鼠、褐家鼠和拉布拉多白足鼠发生三次独立基因复制事件；利用PAML软件的枝模型、位点模型及枝-位点模型计算选择压力，均检测到RNase5基因受到强烈的正选择作用。总之，我们的研究深入系统开展了RNase5在啮齿目中的分子进化，增加了该基因研究的多样性，为进一步系统认识该基因在动物的适应性进化遗传机制奠定了基础。

RNase5 is an important member of the RNASE A superfamily. It has been considered as an intriguing model in molecular evolution studies. 17 species belong to 10 families from three evolution branches of Rodentia are analysised. RNase5 is detected in each genome by TBlastN and BlastN，which suggest the gene is losted in all species of Ctenohystrica after the evolution clade formed. Reconstructed RNase5 trees based on both Neighbor-Joining and Maximum likelihood methods supported three independent gene duplications are observed in Mus musculus, Rattus norvegicus and Peromyscus maniculatus in the mouse-related clade suborder. Strong positive selection was detected in the branch model，site model and branch-site model of PAML. In sum, the present work demonstrated the diversity about RNase5 studies, that provides an important foundation for further studies adaptive evolution mechanism of the RNase5.