Genetic Differentiation And Estimation Of Divergence Time Among Different Geographical Populations Of Brachyrhynchus Hsiaoi (Bl(?)te,1965)

Brachyrhynchus hsiaoi belongs to Insect,Hemiptera,Aradoidea,Aradidae,Brachyrhynchus Laporte,1833.In this study,the genetic diversity of 6 geographical populations was analyzed,2 mitochondrial genes(CO?,16 S rRNA)and 2 ribosomal genes(18S rDNA,28 S rDNA)were selected as the research objects.The genetic diversity and genetic structure of populations were analyzed by haplotype and network,Fst,AMOVA,Tajima'D and Fu'sFs and Mismatch distribution.Thus,the evolution law and historical dynamics of the population were revealed,which provided a theoretical basis for the study of the diversity of Aradidae.In this study,the mitochondrial genes of 6 geographical populations were determined,the phylogenetic tree was constructed based on the mitochondrial gene data,and the population divergence time was estimated by fossil markers.The main results are as follows:(1)The size of the mitochondrial gene of 6 samples is between 15,009-15,247 bp,which is a circular closed DNA molecular structure,which is composed of 37 genes and control region.37 genes include 13 protein coding genes,22 tRNA genes and 2 rRNA genes.23 genes are encoded in the J chain,14 genes are encoded in the N chain.(2)Based on 13 PCGs,7 suborders of Heteroptera and 2 Sternorrhyncha(outgroup)were constructed phylogenetic trees by Maximum Likelihood and Bayesian inference.The results showed that Cimicomorpha was a paraphyletic group,Anthocoridae and Miridae were clustered on one evolutionary branch with Pentatomomorpha,and Reduviidae was a single evolutionary branch.The topological structure of 7 suborders(Enicocephalomorpha +(Dipsocoromorpha +(Gerromorpha +(Nepomorpha +(Leptopodomorpha +(Cimicomorpha +Pentatomomorpha)))))).The topological structure of the ML and BI phylogenetic relationship of the subfamilies of Aradidae was as follows:(Calisiinae +((Aradinae +(Carventinae+ Aneurinae)+ Mezirinae))),and the phylogenetic tree topology of B.hsiaoi from 7 sample sites(including Li hu et al.)(Mangyun-B.hsiaoi +(Xima-B.hsiaoi +(Vietnam-B.hsiaoi +(HekouB.hsiaoi +(Jinxiu-B.hsiaoi +(Tianlin-B.hsiaoi + Chebaling-B.hsiaoi)))))).(3)The divergence time of Heteroptera was estimated by fossil markers.The results showed that the divergence time of Heteroptera was in the Mesozoic Permian,the divergence time of Enicocephalomorpha,Dipsocoromorpha,Gerromorpha,Nepomorpha,Leptopodomorpha,Cimicomorpha,Pentatomomorpha was about 273.18 Ma,258.16 Ma,249.06 Ma,240.14 Ma,232.51 Ma,225.97 Ma,221.54 Ma.The earliest divergence of Aradidae was Aradacanthia heissi,and the divergence time about 192.30 Ma,the divergence time of Aradus compar,Libiocoris heissi,Aneurinae,Between B.hsiaoi and Neuroctenus parus was about 169.10 Ma,130.67 Ma,85.18 Ma,118.64 Ma.Among the population of B.hsiaoi: the earliest divergence of B.hsiaoi was Mangyun-B.hsiaoi was about 88.39 Ma,the divergence time of XiMa-B.hsiaoi,Vietnam-B.hsiaoi,HeKou-B.hsiaoi,JinXiu-B.hsiaoi,TianLin-B.hsiaoi,CheBaLin-B.hsiaoi was about 40.65 Ma,32.12 Ma,12.68 Ma,8.58 Ma,2.28 Ma.(4)A total of 79 mitochondrial COI gene sequences were obtained,and 22 haplotypes were obtained,with Nucleotide diversity was 0.318748±0.153726 and haplotype diversity was 0.8926±0.0195.The genetic variation of the population mainly from among populations,and the Tajima'D and Fu'sFs were not significant.(5)A total of 80 mitochondrial 16 s rRNA gene sequences were obtained and 9 haplotypes were obtained.The haplotype diversity and nucleotide diversity were 0.005747±0.0293 and 0.247058±0.121956.The genetic variation of the population was mainly from among populations,and the Tajima' D and Fu'sFs were positive and not significant.(6)A total of 79 ribosomal 28 S rDNA gene sequences were obtained,and 7 haplotypes were obtained,with haplotype diversity was 0.5962 ±0.0607 and nucleotide diversity was 0.01770 ±0.083825.The genetic variation from among populations,and the Tajima'D was negative and the Fu'sFs was positive,but they were not significant.(7)A total of 66 ribosomal 18 S rDNA gene sequences were obtained;17 haplotypes were obtained,with haplotype diversity of 0.7068 ±0.0553 and nucleotide diversity of 0.110627 ±0.060573;The genetic variation from among populations.Tajima'D and Fu'sFs were negative but not significant.The main conclusions of this study: Cimicomorpha was a parallel group.The earliest divergence of Heteroptera was Enicocephalomorpha.The estimation of divergence time of Aradidae shows that the earliest divergence time was Aradacanthia heiss,and the earliest divergence time was MangyunB.hsiaoi in the B.hsiaoi population,the 18 S rDNA gene was the most conservative,and the evolution of COI gene was the fastest.The variation of B.hsiaoi mainly from among population,and the evolution of the population was relatively stable,and there was no large-scale population expansion.