Conservation Genetics Research Of Apis Cerana From The Western Sichuan Province Based On DNA TRNA^leuCO? Gene Sequence

Apis cerana belongs to genus Apis,family Apidae,order Hymenoptera,class Insecta.Except for Xinjiang,most areas in China have the distribution of Apis cerana.However,due to the influence of Apis melliffera and human activities,the distribution range and population of Apis cerana in China had reduced,and the genetic resources had damaged.At present,Sichuan Province has become one of the main distribution areas of Apis cerana in China.In this study,411 samples of Apis cerana were collected from 23 geographical populations in Sichuan Province.The mtDNA tRNA^leuCO? gene fragments were amplified and sequenced by using molecular biology software for the Conservation Genetics research.The essential results are as follows:The research was successfully amplified the mtDNA tRNA^leuCO? gene fragment of Apis cerana is 436 bp in length,and the average content of A+T and C+G was 85.10%and14.91%,respectively,thus it showed that this gene fragment is an A+T rich region.Moreover,58 variable sites existed in the sequence,including 26 parsimony informative sites,27 single-base mutations and 5 base deletion loci,and 53 haplotypes defined in total.The average nucleotide difference?K?,the nucleotide diversity?Pi?and the haplotype diversity?Hd?were 1.895,0.00440 and 0.886 respectively.The results of mismatch analysis and neutral test showed that the 23 populations of Apis cerana were in the state of population expansion.In the genetic differentiation,the genetic distance?D?between 23 populations was in the range of 0.0020⁰.0136,the genetic differentiation coefficient?Fst?was-0.103⁰.549,and the gene flow?Nm?was 0.205⁺?.The Fst and Nm showed that there was a large gene flow between populations.According to the results of molecular variation analysis?AMOVA?,the variation of Apis cerana mtDNA mainly occured within the population,the population had moderate level of genetic differentiation.The Network and the phylogenetic tree showed that the haplotype clustering has an obvious phylogeographic pattern,and the AMOVA level analysis showed that the Daocheng,Derong,Batang and Jiulong were clustered into one group.Xinlong,Danba,Kangding,Daofu,Luding,Xiaojin,Jinchuan,Malkang,Heishui,Lixian,Wenchuan,Baoxing,and Qionglai were clustered into one group.Maoxian,Qingchuan,Cangxi,Fushun and Shimian were gathered into another group.Mianning was a single group.There are obvious structural differences among 23geographical populations.According to the obtained results,the Apis cerana in western Sichuan can be divided into 2 Evolutionary significant units?ESU?.Daocheng,Derong,Batang and Jiulong belong to an ESU;Xinlong,Danba,Kangding,Daofu,Luding,Xiaojin,Jinchuan,Malkang,Heishui,Lixian,Wenchuan,Baoxing and Qionglai are an ESU.This study was the first large-scale analysis of the differences in mtDNA tRNA^leuCO? gene sequences of Apis cerana in western Sichuan,revealing the genetic diversity and historical dynamics of the population,expounding the genetic structure and genetic differentiation between populations,and finally dividing into 2 ESU.The research provided some informations for the resource conservation of the Apis cerana in Sichuan Province.In the future research,molecular markers such as the whole genome and SSR will be used to solve the population situation of Apis cerana in China as soon as possible,so as to better protect and utilize the genetic resources of Apis cerana in China.