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Genetic Differentiation And Phylogeography Of Geographic Populations Of Dendrolimus Punctatus

Posted on:2020-01-10Degree:MasterType:Thesis
Country:ChinaCandidate:Y WangFull Text:PDF
GTID:2393330578976069Subject:Forest Protection
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The Dendrolimus punctatus Walker(Lepidoptera:Lasiocampidae),has large geographic distribution range in China,which is the most important conifer defoliators in China.In order to explore the genetic differentiation,population dynamics,origin and spread among the geographical populations of D.punctatus,the study collected specimens from 15 geographical populations from 9 provinces(Hubei,Hunan,Jiangxi,Sichuan,Chongqing,Guizhou,Guangdong,Guangxi and Anhui),with 3-4 samples per population,for a total of 48 samples.Two molecular markers were used for the study.One is the ribosomal DNA transcribed spacer ITS1,which was amplified by PCR using specific primers and entrusted to Beijing Qingke Biological Company for sequencing;the other is the mitochondrial genome,which is sequenced using high-throughput sequencing.The main conclusions are as follows:1?ITS1 sequence and Mitochondrial gene sequence of Dendrolimus:Excluding the failed sampling samples,and sorting out the bases that were not sequenced at both ends,the final 42 ITS1 sequence fragments were obtained,which is 652 bp long.A total of 58 mitochondrial genomes of Dendrolimus were obtained by high-throughput sequencing(Illumina HiSeq sequencing),including 44 mitochondrial genomes of D.punctatus,2 mitochondrial genomes of D.houi,and 12 mitochondrial genomes of D.kikuchii.The mitochondrial sequences of D.houi and D.kikuchii were used for the phylogenetic study of the genus Dendrolimus,and the genus D.houi was also used as an outgroup for phylogenetic analysis of different geographical populations of D.punctatus.2?Mitochondrial genome sequence and phylogenetic analysis of D.punctatus:The results indicated that the complete mitochondrial genome of D.punctatus is a circular molecule of 15417bp,including 13 protein-coding genes,22 tRNA genes,2 rRNA genes and one control region without gene rearrangement.The phylogenetic relationship of 29 insects in 12 families of Lepidoptera moths was constructed based on the nucleotide sequence of the mitochondrial genome.The phylogenetic relationships among the Lepidoptera moths:((((((((Lymantriidae+Arctiidae)+Noctuidae)+Notodontidae)+(Geometriidae+(Bombycidae+(Sphingidae+Satumiidae))))+Lasiocampidae)+(Pyralidae+Cramnidae))+Tortricidae)+Hepialidae).The results of internal phylogenetic analysis of the Dendrolimus show:(((((D.tabulaeformis+D.punctatus wenshanensis)+D.spectabilis+D.superans)+(D.houi+D.kikuchii))+Bombyx mori).3?Genetic diversity analysis of geographical populations of different geograpgical populations of D.punctatus:The three most variable gene sequences(ND2-COX1-ND5)were selected from the mitochondrial genome of D.punctatus,hereinafter referred to as the combined gene.Genetic diversity analysis of D.punctatus populations using ITS1 and combinatorial genes as molecular markers,sampling points in 9 provinces.The results show:Both molecular markers showed high genetic diversity in Sichuan,Guangxi and Guizhou populations,indicating that there may be ancestral populations in the three populations;Hunan populations show lower genetic diversity,may be a younger population,or have just experienced a bottleneck effect;Other populations showed high haplotype diversity and low nucleotide diversity,suggesting that these populations may be formed by the rapid growth of a small effective population,although the haplotype polymorphism was accumulated by variation,but However,it has not yet accumulated the diversity of nucleotide sequences.4?Phylogenetic analysis and genetic structure analysis of different geographical populations of D.punctatus:An NJ phylogenetic tree was constructed based on the ITS1 sequence of D.punctatus.The ITS1 molecular marker divides the population of D.punctatus into two large branches A and B.The A branch is dominated by the plains in the middle and lower reaches of the Yangtze River.It also includes some populations in Jinping,Guilin,Guangxi,and Dazhu,Sichuan.There is no significant geography within the branche.The B branch includes the Sichuan Basin population?the Guangxi Baise and Guangdong Luoding population,and the three populations are each clustered.Genetic structure analysis showed that the internal genetic differentiation coefficient of A branch is small,with a large gene flow,and the internal genetic differentiation of B branch was obvious.Discarding populations that are insufficiently sampled due to sequencing failure,and the remaining 12 geographic populations are divided into 3 groups according to phylogenetic analysis.HBDW,HBHG,HNCZ,HNDA,JXYD and AHHF populations are a group.SCDZ,SCYB,CQNC and GZJP populations are a group.GDLD and GXBS are a group.AMOVA analysis showed that 54.73%of genetic variation was distributed among the three groups,and the genetic variation among different geographical populations within the three groups accounted for only 7.05%,and 38.22%of the genetic differences came from within the geographical population.NJ and Bayesian phylogenetic trees were constructed based on the mitochondrial genome of D.punctatus.Based on the phylogenetic analysis of mitochondrial genome,the population of D.punctatus was divided into four branches:A branch is a geographical population of the middle and lower reaches of the Yangtze River dominated by Hubei,Hunan,Jiangxi and Anhui(D.pun HBDW,D.pun HBHA,D.pun HNCZ,D.pun HNDA,D.pun JXYD,D.pun JXXG,D.pun AHHF);Guangdong Luoding population is individually clustered as B with a support rate of 100;C is a geographical population dominated by the Sichuan Basin(D.punCQNC,D.punCQYB,D.pun SCDZ);D branche includes Guangxi Baise(D.pun GXBS)and Sichuan Yibin(D.pun SCYB)population.Genetic structure analysis showed that the four branches had a relatively low level of internal genetic differentiation except for the D branch,especially the frequent gene flow inside the A branch.According to the phylogenetic analysis results and geographical location,the D.punctatus is divided into 2 groups.The plains of the middle and lower reaches of the Yangtze River and the Jinping population of Guizhou are a group.Sichuan Basin population and Guangdong and Guangxi populations are a group.AMOVA analysis showed that the genetic differentiation among the populations of D.punctatus is very high,and most of them were distributed among individuals of geographical populations.5?Historical dynamics and the time of the most recent common ancestor(TMRCA)of geographical populations of D.punctatus:Based on two molecular markers(ITS1 and combinatorial genes),the Tajima's D and Fu's Fs values of D.punctatus populations were analyzed.The results showed that the population of D.punctatus experienced recent population expansion.The results of BSP analysis showed that the population of D.punctatus was in a stable state for a long period of time,and the population of D.punctatus expanded rapidly after 0.1 million years ago.It also proved that the population of D.punctatus experienced population expansion in the past.The ancestral analysis of different geographical populations of D.punctatus showed that the divergence of D.punctatus began at 0.3465 million years ago(95%HPD:0.3892?0.3058 million years ago),corresponding to the Lushan glacial period of the Quaternary glacial period in China(0.37?0.24 million years ago),the large-scale disagreement began between 0.1 and 0.07 million years ago,which is consistent with the results of the BSP analysis.Based on the analysis of genetic diversity?phylogenetic analysis and TMRCA,it is presumed that the Sichuan Yibinand Guangxi Baise may be the refuge for the D.punctatus during the ice period,and also the starting point for the post-glacial diffusion.The population of D.punctatus experienced alternating cold and warm during the glacial-interglacial period.The populations of the two origins began to spread from west to east.The population of Yibin in Sichuan spread to the middle and lower reaches of the Yangtze River through Guizhou,and the population of Guangxi spread eastward to Guangdong.6?In summary,this study based on the mitochondrial gene and nuclear gene markers for the first time to study the genetic differentiation of different geographical populations of D.punctatus.The origin and differentiation of D.punctatus were revealed,which provided a molecular theoretical basis for analyzing its adaptive evolution and formulating corresponding precise prevention and control measures.
Keywords/Search Tags:Dendrolimus punctatus, Mitochondrial genome, Genetic structure, Phylogenetic, phylogeography
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