Population Genetic Diversity And Phylogeography Of Mongoloniscus Sinensis(Dollfus,1901)(Isopoda: Oniscidea)

Mongoloniscus sinensis?Dollfus,1901?as an endemic specise to the palaearctic of China,it has certain tolerance and enrichment to heavy metals and can be used as remedy group to heavy metal pollution.In the present paper,Mongoloniscus sinensis was used as the research material,and the collected areas spaned 7 provinces including Shanxi,Hebei,Beijing,Henan,Liaoning,Shaanxi and Shandong,with a total of 26 populations.PCR amplification was conducted based on mtDNA?12S,ND5,COI?.By using the method of single gene and 3 genes combined analysis,the population dynamic evolution and the evolutionary path of Mongoloniscus sinensis was analyzed;discussing the advantages and disadvantages of different molecular markers,so as to provide molecular evidence for the phylogenetic development and fill in the specific distribution situation of Mongoloniscus sinensis in China.The results of this paper are as follows:1:A total of 500bp of 12S gene,600bp of COI gene,629bp of ND5 gene and 1729bp of 3 genes combination were obtained through comparative splicing.The overall sequence was characterized by high A+T content,high variation in the third codon of the protein-coding gene,and significantly more than transmutation in all gene sequences.All genes sequences were significantly more transformed than Transvered.2:Among the 234 sequences,there were 70 haplotypes of 12S gene and 5 Shared haplotypes.The overall mean haplotype diversity?Hd?and nucleotide diversity?Pi?were 0.9361 and 0.0638.There were 72 haplotypes of COI gene,9Shared haplotypes,Hd was 0.9038 and Pi was 0.0586.ND5 had a total of 44 haplotypes and Shared 12 haplotypes,with Hd of 0.9274 and Pi of 0.0359.There were166 haplotypes of the combined genes,9 Shared haplotypes,Hd was 0.9876 and Pi was 0.0356.In general,haplotype diversity was higher in DT,WT,SZ,XDQ;Some populations such as DCQ,XX,WYQ,there was only one haplotype diversity.3:The genetic diversity of the population is not high on the whole,and there are some regions with high population diversity,mainly distributed in the north of north China,such as DT,SZ and WT,which all show high genetic diversity of the population,and with the gradual southward movement of the distribution,the population diversity shows a decreasing trend.4:AMOVA showed that the variation of the 26 populations was mainly from within the population;The results of mismatch distribution and neutral test showed that the Mongoloniscus sinensis did not experience the expansion recently, but the Tajima's D of some populations showed a significant negative value,and there was a slow expansion of some populations.The average F_stt was positively correlated with the distance between the two populations.5:Based on the phylogenetic tree and haplotype network diagram, combining with the influence of quaternary glaciers on the species in the palaearctic boundary of China,it is believed that the origin region of Mongoloniscus sinensis in China is the north China plain,which is consistent with the inference of single gene?COI?in the early stage.However,the further analysis and comparison of the evolutionary path showed that in addition to following the evolutionary path from north to south,there was a trend of turning back to north in the later period,and almost every gene's phylogenetic tree showed this characteristic.Combined with the characteristics of climate change in recent 50 years,it was found that the migration of Mongoloniscus sinensis should be related to global warming.This special evolutionary path,to a certain extent,warns human beings that global warming cannot be ignored.The devastating disaster brought by global warming is immeasurable and should arouse universal concern of human beings.6:In phylogenetic analysis,there were many parallel branches in 12S gene,which could not be further refined.Combined with the conservative characteristics of12S gene,it was suggested to apply this gene in the identification of above species level in the future.Since the use of molecular markers,COI gene has been recognized as a good marker type at the species level and below,which has been confirmed again in this study.In the past,ND5 gene was considered to be suitable for the above species level.Comparing with the results of this study,the ND5 gene was considered to be equally applicable for the below species level of Mongoloniscus sinensis.