Genetic Diversity And Molecular Phylogenetic Analysis Of Sorex Caecutiens In Northeast China

Sorex caecutiens is a small mammal which belongs to the Sorex of the family Insectivora(Soricidae).This article mainly used the method of trap,equipped with clamp method to take samples.The sampling sites are located in Da Hinggan Ling,Xiao Hinggan Ling and Changbaishan in the northeastern China,including 9 distribution areas.Based on Cyt b gene molecular marker method,the genetic diversity and molecular system geography of Sorex caecutiens in northeastern China were studied.The results show:(1)The full sequence of Cyt b gene was 1140 bp,and 81 haplotypes were obtained from 99 samples.The haplotype diversity was 0.9940,the average number of nucleotide differences was 5.3290,and the nucleotide diversity was 0.0047.The range of nucleotide diversity in the 3 populations was 0.0036-0.0058,indicating that the genetic diversity was high in the northeast of China,and the genetic diversity among the populations was not significantly different.(2)Based on Cyt b gene markers,the genetic distance of the 3 populations was between 0.0043 and 0.0053,and the genetic distance of 9 sampling points was between 0.0030 and 0.0061;the phylogenetic tree was constructed by using Neighbour-joining based on haplotype.The same results were obtained by structuring phylogenetic trees(NJ?MP?ML),S.caecutiens were clustering in a large branch instructions;It showed that there is no obvious further genetic differentiation among them in northeast China.(3)Neutral test to calculate the genetic differentiation: the range of F-statistics among the 3 populations is 0.0145-0.0382,and the number of migrants per generation among the 3 populations is 13.0983-34.4250,indicating the genes degree among the 3 populations is similar,the genetic differentiation among the populations is not obvious.Tajima's D neutrality test showed the population difference in the northeastern China was not significant(D=-2.6151,P < 0.001),indicating there was no non-neutral evolution in the Northeast China.The results of the 3 populations showed no significant negative values.It showed that there is no non-neutral evolution.There is the possibility of historical expansion.Fu's FS neutral test showed the population difference in the northeastern china was siginificant(Fs =-124.8540,P <0.001),showing a significant negative difference,indicating that the Northeast has experienced a historical expansion of the whole S.caecutiens;Analysis of molecular variances show that the differentiation among the three populations account for only 2.48% of the total,the differentiation within the sampling location account for only 0.34% of the total,and the genetic differentiation within the sampling location account for 97.19% of the total;The mismatch distribution were used to analyze the samples data,showing that all the S.caecutiens in the north-east of China experienced a typical population expansion in the process of evolution.The Da Hinggan Mountain populations has experienced a complex history.Xiao Hinggan Ling and Changbaishan mountain populations have experienced populations expansion.Molecular system geography results indicate: The phylogenetic tree was constructed based on the complete Cyt b gene of S.caecutiens from northeastern China and GenBank downloaded from other regions.The genetic distance was between 0.0038-0.0227;three phylogenetic trees(NJ,ML,and MP)were constructed and displayed the same results.It was found that Hokkaido,Japan was clustered in one small differentiation branch,and the other was clustered in Jeju Island,Korea and the others formed a large branch.There is no apparent further differentiation of the genetic structure on this large branch;a major haplotype in northeastern region of China(consisting of two Xiao Hinggan Ling samples and two Changbaishan mountain samples)was appeared in the near-central position of the pedigree.There are three branches that are more widely separated in the Median-joining network.The farthest branch is the branch of Hokkaido,Japan.The next is in the Jeju Island,Korea.The nearest is in the Ussuri and Nagorno,Russia;The analysis of the network and the phylogenetic tree both show that the distribution of S.caecutiens in the Eurasian continent didn't indicate obvious geographical system differentiation,in addition to Hokkaido,Japan and Jeju Island,Korea.