Phylogeography And Genetic Differentiation Of Erythroneurini From Southwest Karst Region

Erythroneurini is the most abundant and diverse group of Typhlocybinae,mostly occurring in forests with abundant and succulent vegetation leaves or where plants grow wildly and weeds are abundant.As a phytophagous insect,its population occurrence dynamics and distribution pattern are mostly influenced by host plants and climate,with good indicators for ecological environment,geographical isolation,latitude and altitude.Currently,research on this group of insects is mostly focused on classification,hazards,control applications,phylogeny,and community structure,while research on lineage biogeography is relatively rare.In this study,leafhopper specimens were collected from 25 counties and cities in five provinces in southwestern Karst regions of China,and Seriana bacilla which is distributed in all five provinces was selected for population genetics and phylogeography after anatomical identification.The results of this study are as follows:1.The complete mitochondrial genome of Seriana bacilla and other9 approximate species(Empoascanara quarta,Empoascanara defecta,Empoascanara plamka,Empoascanara alami,Empoascanara circumscripta,Empoascanara angkhangica,Empoascanara hongkonica,Empoascanara sp.Empoascanara falcata)have been sequenced.The Mitochondrial genome length of Seriana bacilla is 15,613 bp,and other nine Empoascanara species are 15,354 bp,15,575 bp,15,338 bp,15,255 bp,14,928 bp,15,494 bp,15,279 bp,15,739 bp and 15,151 bp respectively.All sequenced species have gene spacing,gene overlap,and no gene rearrangement,with obvious AT bias.Among the 13 protein-coding genes,ATN(ATA,ATG,ATT)is used as the starting codon,except ATP8,ATP6,and ND5,which use TTG as the starting codon.Except COII and ND5,which use single T as the ending codon,the other genes use TAA and TAG as the ending codon.All 22 t RNAs have base-pair mismatches.Except for t RNA-Ser1,all t RNAs can form a typical clover secondary structure.2.The phylogenetic tree of ML and BI obtained based on 13 PCGs indicates that the relationship between the six tribes of Typhocybinae is((Typhocybini + Zyginellini)+(Erythroneurini + Dikraneurini))+(Empoascini + Alebrini).The phylogenetic relationship between the two genera of Seriana Dworakowska and Empoascanara Distant was confirmed from a molecular perspective.Further analysis of the combined gene(COI + COII + Cytb + 16 S r RNA)revealed that Seriana bacilla and Empoascanara gracilis are relatively distant and closer to Empoascanara angkhangica.The divergence time estimation shows that the divergence time of Typhrocybinae is about 113.59 million years in the middle of the Cretaceous,the divergence time of Erythroneurini is about 85.521 million years,and the origin of Seriana bacilla is about 54.85 million years ago in the Paleogene.3.48 sequences of 4 mitochondrial genes(COI,COII,Cytb,and 16 S r RNA)from 12 geographical populations of Seriana bacilla have been obtained,and the genetic diversity of different geographical populations of Seriana bacilla has been studied.It is concluded that Guizhou has the highest genetic diversity,followed by Sichuan,and Chongqing has the lowest genetic diversity.It is speculated that the population of Chongqing might be a young population,or have experienced "selective elimination" or the "founder effect".4.Phylogenetic analysis and haplotype analysis of different geographical populations of Seriana bacilla support its classification into three evolutionary branches.The results of molecular variation analysis(AMOVA)show that the genetic variation of Seriana bacilla is mainly from individuals,and that the genetic variation between evolutionary branches and regions is small.Based on the results of the genetic differentiation coefficient,gene flow,and genetic distance between different geographical populations,it is speculated that geographical isolation is the main reason of genetic variation in Seriana bacilla.Both the neutral test and the mismatch analysis showed that Seriana bacilla had not experienced rapid population expansion,which means that the environment in southwest China is suitable for the growth of this species.5.The estimation of divergence time showed that Seriana bacilla originated in the Paleogene period,and the evolution branches began to diverge from 3 to 14 million years ago.Most of the population differentiation within the evolution branches concentrated in 0.329~4.601 million years,including the Pleistocene and Pliocene periods.It is speculated that the Seriana bacilla has experienced the fourth ice age and the orogeny of the Qinghai-Tibet Plateau and Hengduan Mountains.According to the results of the ancestral region reconstruction,phylogenetic analysis and genetic diversity analysis,it is considered that the Yunnan-Guizhou Plateau and Sichuan Basin are the sanctuaries of Seriana bacilla during the ice age,and after the ice age,they spread from the sanctuaries to four sides,forming the current distribution pattern.6.Using the maximum entropy model to predict the potential suitable areas of the past,present and future of Seriana bacilla in China,and the habitat was divided into four types: unsuitable areas,lowly suitable areas,moderately suitable areas,and highly suitable areas.The results were visualized using Arc GIS 10.7 software,showing that the suitable area of Seriana bacilla has not significantly changed in other periods except for a significant increase in the area from the Last Glacial Maximum to the Middle Holocene.The suitable areas are mostly concentrated in the humid areas of southern China,and the highly suitable areas are concentrated in Guizhou Province,Sichuan Province and Chongqing City.The results indicate that temperature and precipitation are the main factors affecting the distribution of this species,and provide a reference for the collection,investigation,resource utilization and control of the species of Seriana bacilla in the future.