基于线粒体控制区的粤闽三线矶鲈地理群体的遗传变异分析

Genetic variations among Parapristipoma trilineatus in coastal waters of southeast China based on mt DNA control region sequences

对中国东南沿海福建平潭和广东汕头、闸坡3个群体38 ind三线矶鲈（Parapristipoma trilineatus）线粒体控制区的914 bp序列进行分析,发现22个变异位点,共有33个单倍型.3个群体总体的单倍型多样性和核苷酸多样性均较高（H=0.991 0±0.009,π=0.005 8±0.000 4）,其中平潭和汕头群体分别表现出最低和最高的核苷酸多样性（π=0.004 9±0.000 5和0.0066±0.0009）.3个群体间的Fst值为0.056 6～0.105 3,Nm值为4.248 3 ～8.333 4,表明3个群体间存在较低分化,可作为1个管理单位进行保护,建议优先保护汕头群体.在简约性网络图中单倍型呈星状分布,中性检验Fu＇s Fs为显著负值和核苷酸不配对分析呈现单峰分布,表明三线矶鲈在历史上经历过种群扩张事件,推测扩张年代约为晚更新世的9.81～2.45万年前.

Threeline grunt（Parapristipoma trilineatus） is a warm-ocean economic fish endemic to the coast of northwest Pacific, which mainly distributes in coastal waters of southern Japan, the East China Sea and South China Sea and Taiwan. Due to environmental pollution and overfishing, the population has decreased rapidly and its＇ germplasm declined significantly in recent years. With the development of artificial breeding techniques, P. trilineatus aquaculture is expanding fast, but the escape of breeding individuals could lead to hybridization with wild populations and reduce their genetic diversity, thus it＇ s urgent to take effective measures to conserve wild populations. In this study 914 bp sequences of control region of 38 P. trilineatus individuals collected from three sampling locations in the southeast coast of China, including Pingtang （PT, n = 13 ）, Shantou （ ST, n = 12 ） and Zhapo （ ZP, n = 13 ） were used for genetic diversity analysis, of which 22 mutations of nucleotide acids and 33 haplotypes were detected. Apart from two haplotypes shared by the two populations, the remaining haplotypes were unique to each population. In the Kimura2-parameter-based neighbor-joining tree and parsimony network of P. trilineatus haplotypes constructed by TCS, haplotypes with different geographical origins were intertwined together, indicating that there was no obvious phylogenetic structure nor geographical structure. Overall haplotype and nucleotide diversity were 0. 991 0 ± 0. 009 and 0. 005 8 ± 0. 000 4 respectively, suggesting a pattern of high haplotype diversity and nucleotide diversity. Nucleotide diversities of PT, ST and ZP populations were 0. 004 9 ± 0. 000 5,0. 006 6 ± 0. 000 9 and 0. 005 3 ± 0. 000 4 respectively. Pairwise Fst from PT to ZP and ST were 0. 061 6 （P 〉 0.05 ） ,0. 056 6 （ P 〉 0.05 ）, and Fst between ST and ZP was 0. 105 3 （P 〈 0.05 ）, and the gene flow （Nm ） of the three population were 8. 333 4,7. 616 9 and 4. 248 3 respectively, revealing that there was no obvious geographical differentiation among three populations, and they could be treated as a single management unit. As ST population had the highest nucleotide diversity, it should be protected in priority. The significant negative values of neutral test （Fu＇ s Fs = - 6. 1089, P 〈 0.05 ） , the unimodal mismatch distribution and star-shaped distribution of haplotypes in the parsimony network all suggested that a recent population expansion had occurred （in the late Pleistocene） （98.1 ka BP-24.5 ka BP）, which might be probably related to fluctuated sea levels caused by the Late Pleistocene glacial cycles. High dispersal ability and absence of obvious geographic barriers may hinder the differentiation among populations of East China Sea and South China Sea, causing genetic homegeneity among P. trilineatus. For better protection and sustainable development of wild resources of P. trilineatus, larger sample size with more geographic coverage, combined with other molecular markers, such as microsatellite, AFLP and Single Nucleotide Polymorphisms etc. are needed to comprehensively understand the genetic background of P. triliueatus.