The Classification And Phylogeny In Red-toothed Shrews,genus Sorex(Soricinae,Soricidae) In China

Shrew is controversial in the past because the past studies were mainly based on morphological methods and the species of this group are extremely conservative and similar in morphology.In this study,the mitochondrial gene fragment(COI,CYTB)and nuclear gene fragment(APOB,BRCA1,BRCA2,GHR,RAG2)of Chinese Shrew were collected and amplified,and the phylogenetic relationship of Chinese Shrew was reconstructed by the construction of phylogenetic tree.The results of molecular phylogeny were verified by using fossil correction points and "loose" molecular clocks to estimate the differentiation time of species,and at the same time to use the "traceability theory" of species definition and species tree construction to verify the results of molecular phylogeny.The relationship between species suggested by phylogenetic analysis was evaluated.Finally,morphological analysis was carried out on all intact shrew skulls.The results shows that:(1)the present study supports the species status of 15 shrew species in China,and divides the 15 species into 5 related groups.(2)Molecular clock correction shows that the recent common ancestor of Chinese Sorex dates back to the mid-Miocene(9.56 Ma,95% confidence interval: 16.78-4.46).(3)The distribution of S.thibetanus has been discovered in Tibet for the first time,which is a new animal record in Tibet autonomous region.The distribution of S.cansulus has been extended to qinghai,sichuan and shaanxi.Since then,this group has been rapidly differentiated at the end of Miocene and the beginning of Pliocene.We analyzed the morphology of the intact skulls collected from Nanjiang No.6 with black back-striped shrew No.6 and two extant species of shrews with black dorsal grain,including 90 S.bedfordiae(including five subspecies)and 33 S.cylindricauda.At the same time,the molecular phylogeny of 45 specimens of Sorex including 37 S.bedfordiae(including five subspecies)and four S.cylindricauda were studied to explore the species diversity.We have amplified one mitochondrial gene(CYTB,1140bp)and two nuclear gene fragments(APOB,455bp;).(BRCA,1728bp),using Bayesian(BI)and maximum likelihood(ML)to construct phylogenetic tree,and using all three genes to construct a * BEAST merging species tree through BEAST v1.7.4.The results showed that the tail length of S.nanjiangensis sp.nov was almost equal to that of 3/4,S.bedfordiae of body length,and there was significant difference in TL,CIL and IOB between the two groups(p < 0.05).There were significant differences in somatotype and skull measurement between S.nanjiangensis sp.nov and S.cylindricauda(P < 0.05).From molecular phylogeny,both BI tree(BPP=1.0/1.0),ML tree)and species tree(BPP=1.0)support S.nanjiangensis sp.nov to form a single evolutionary branch.Based on morphological and phylogenetic analysis,the blackstriped shrews collected in Nanjiang are independent species,so we name the species S.nanjiangensis sp.nov,and describe it in detail.