基于线粒体DNA控制区的斑翅草螽不同地理种群遗传分化研究

采用PCR扩增结合DNA克隆测序技术,分析了斑翅草螽Conocephalus maculates 9个地理种群mtDNA控制区序列的变异及遗传多样性.切除侧翼RNA基因序列后,最终获得的斑翅草螽mtDNA控制区比对后全长为676 bp,平均碱基组成T(37.8％),C(11.7％),A(41.3％)和G(9.1％).共检测到98个可变位点,占总位点数的14.5％,其中,9处碱基插入/缺失,74处转换(40个T/C,34个A/G),50处颠换(18个A/T,11个T/G,15个A/C,6个C/G).共定义46个单倍型,其中,4个为种群间共享单倍型(H02、H05、H08和H10),其余42个为各种群独有单倍型,包括6个种群内共享单倍型(H09、H11、H15、H18、H26和H38).单倍型总数占实验个体总数的69.7％,除四川峨眉山外,其余种群单倍型百分比均＞50％.通过两两地理种群间的FST值差异显著性检验,将这些群体分为4组,分别为SC+CQ,GX+FLB+HN+YN,XZ和HB.以长瓣草螽C.gladiatus、峨眉草螽C.emeiensis、悦鸣草螽C.melaenus、竹草螽C.bambusanus为外群,构建的斑翅草螽mtDNA控制区单倍型NJ法系统树形成3个自举支持度较高的分支,其中,分支A由28种单倍体组成,包括本研究中除四川峨眉山(SC)和重庆万州(CQ)以外的7个种群；分支B由12种单倍体组成,包含除菲律宾拉乌尼翁(FLB)和江西南昌(JX)以外的7个种群；分支C由6种单倍型组成,全部来自西藏林芝(XZ)的单倍型.聚类结果表明,斑翅草螽不同地理种群间的遗传分化并不明显,即使是两两群体间FST值差异显著的群体,也未能形成完全独立的分支.

Genetic diversity of Conocephalus maculatus of different geographic populations based on mitochondrial DNA control region analysis

Polymorphism of sequence variations in mitochondrial control region was assessed to explore the level of genetic variability and differentiation among nine populations of Conocephalus maculatus (Orthoptera: Tettigoniidea) from China and Filipine. PCR was used to amplify the control region fragment in 66 individuals of C. maculatus collected from Chongqing (CQ), Filipine (FLB), Guangxi (GX), Hebei (HB), Hainan (HN), Jiangxi (JX), Sichuan (SC), Xizang (XZ) and Yunnan (YN). A mitochondrial DNA (mtDNA) fragment of 1259 aligned bp was sequenced in these 66 C. maculatus individuals. The fragment sequenced for each of the 66 individuals that include a partial sequence of rrnS, control region, trnI, trnQ, and a partial sequence for trnM. The size of control region was 676 bp, with nucleotide frequencies of T (37.8%), C (11.7%), A (41.3%) and G (9.1%). A Total of 46 haplotypes from 66 mtDNA control region sequences were identified, with 98 variable sites (14.5% of total analyzed sites). Only four of these haplotypes were shared by individuals from more than one population, six haplotypes were shared by more than one individual within population. The analysis of molecular variance (AMOVA) showed that the percentage of variation within populations (62.94%) was greater than that among populations (37.06%). In the hierarchical AMOVE, both the ''among populations'' and ''within populations'' variance components were considerable high, the latter was more contribution to total variances than the former. Levels of genetic variation within C. maculatus populations were higher than among them. F_ST analyses reveals that no significant (P>0.05) genetic differences between SC and CQ, and between any two populations of GX, FLB, HN and YN. There are significant (P<0.05) genetic differences between remaining any two populations. We may be a preliminary clustered them into four groups, SC+CQ,GX+FLB+HN+YN,XZ and HB. Phylogenetic analyses between the 46 haplotypes based on Neighbor-Joining cluster into three phylogenetically well supported clades. Clade A is formed with 28 haplotypes from all populations other than SC and CQ; Clade B is formed with 12 haplotypes from all populations other than FLB and JX; Clade C is formed with 6 haplotypes from XZ population. These results may suggest that no significant genetic differences among populations, even for those F_ST analyses significant (P<0.05) populations.