Phylogeographic Distribution Pattern Of Ducetia Japonica Inferred From Mitochondrial COI And Microsatellite Markers

Ducetia japonica?Orthoptera: Tettigoniidae?is widely distributed in China.In this study,11 polymorphic microsatellite loci were screened from the genome of D.japonica,genotyping was performed on 691 individuals,and 796 mitochondrial cytochrome oxidase I?mtDNA COI?sequences were successfully amplified.A total of 79 domestic populations and 2 foreign populations?Singapore and Laos?were involved in this study,and the domestic populations were divided into Northeast region,North region,Central region,South region and Southwest region according to the geographical distribution division of animals in China.In order to study the genetic structure and genetic diversity of D.japonica by using two different molecular markers of microsatellite DNA and mtDNA COI,and the distribution of D.japonica in China was predicted.The main researches were shown as follows:1.Based on Maxent model and Arcgis spatial analysis technique to predicte the distribution of D.japonica in China.The results showed that the average of AUC value is 0.892,the precipitation of driest month?bio14?,precipitation of wettest month?bio13?and mean temperature of warmest quarter?bio10?were the strongest predictors of D.japonica distribution with 39.3%,31.6% and 9.2% contributions,respectively.For the prediction of the future?2050,2070?,the total susceptibility zones of the two representative concentration pathways RCP26 and RCP85 are smaller than the total habitats in the current climate.2.A total of 159 haplotypes were found through the analysis of COI sequences,among which shared haplotypes accounted for 18.87%,unique haplotypes accounted for 81.13%,and Hap₃ was the largest haplotype.Overall,haplotype diversity?Hd?is 0.9307,nucleotide diversity???is 0.01391,and the mean nucleotide difference?k?is 9.150.From the perspective of five geographical regions,the genetic diversity of the Northeast China is significantly lower than other regions,with haplotype diversity and nucleotide diversity being 0.585 and 0.00113,respectively.From the haplotype network,it can be seen that the largest haplotype is located in North China,and most populations which are geographically close will gather together.The NJ tree constructed based on haplotypes,populations in the Northeast China and North China are located at the base of the phylogenetic tree,and the South China and Southwest China are located at the end of the phylogenetic tree.3.Based on the microsatellite data,the mean observed heterozygosity?Ho?and expected heterozygosity?He?of eleven loci is 0.599 and 0.639 respectively.The polymorphism information content?PIC?ranged from 0.079 to 0.922,and all loci deviated significantly from the Hardy-Weinberg equilibrium?HWE?.The number of domestic populations alleles?Na?ranged from 3.364 to 16.545,the levels of observed heterozygosity and expected heterozygosity ranged from 0.384 to 0.857 and from 0.571 to 0.883,respectively.Compared with other regions,the genetic diversity of the Northeast region is relatively low,and the observed heterozygosity and expected heterozygosity were 0.569 and 0.829,respectively.The UPGMA phylogenetic tree constructed based on microsatellite data is divided into two branches,one is the Northeast region,the other is a cluster?North region and Central region clustered together,and South region and Southwest region clustered together?.The clustering result of the STRUCTURE shows that the Northeast region has a single structure,and there is gene penetration among populations in other regions,and the north region has the most abundant populations structure.This result also indicated that the populations of the Northeast region was far from other regions in terms of evolutionary relationship,and has occurred certain genetic differentiation.4.The results of genetic differentiation of the two molecular data show that the regions except the Northeast region are at the level of moderate and low genetic differentiation.Gene flow between the central China,south China and southwest China was strong,and the degree of genetic differentiation between the foreign populations?Singapore and Laos?and South China is the minimal.Mantel test also shows that there is a positive correlation between geographical distance and genetic distance.5.The sudden expansion model was used to test the mismatch distribution in five geographical regions,only the observation curve and the simulation curve of North region were fitted.Meanwhile,the results of the neutral test showed that the Tajima's D and Fu's Fs values in North region were negative and significantly deviated from the neutral hypothesis?P < 0.05?,while the SSD and r values were not significant,which indicated that the hypothesis of population expansion could not be rejected and further confirmed that North region had experienced population expansion.