长江口及其南部邻近地区大弹涂鱼种群遗传结构及种群历史分析

Genetic Structure and Population History of Beleophthalmus petinirostris in Yangtze River Estuary and Its Southern Adjacent Regions

应用随机扩增多态性DNA(RAPD)技术及细胞色素b(Cytb)基因序列,分析了长江口及其南部邻近地区大弹涂鱼(Boleophthalmus pecinirostris)群体遗传结构及种群历史,结果显示这一区域大弹涂鱼群体的遗传多样性水平很高。(1)RAPD分析结果:从100个10碱基随机引物中筛选出30个多态性引物,对长江口九段沙湿地、浙江舟山定海、福建霞浦群体各20个体进行RAPD分析,3个群体分别获得236、270、274条带,共301个有效位点。3群体多态位点比例(P)、Nei基因多样性指数(H)、Shannon多样性指数(I)分别在93.02%—96.35%、0.3890—0.4219、0.5618—0.6044。分子方差分析(AMOVA)表明,大弹涂鱼群体间存在显著的遗传分化(Fst=0.03004-0.03254,P<0.05),但仅3.2%的遗传变异来自群体间。(2)Cytb基因序列分析结果:从采自九段沙、定海、霞浦及浙江慈溪的42尾大弹涂鱼样本中,共获得33个Cytb基因单倍型(序列长1141bp)。4群体的平均单倍型多样性(h)、核甘酸多样性(π)分别为0.9814、0.0048。4群体间的遗传分化指数Fst为0.00043—0.07814,仅1.93%的变异来自群体间(AMOVA分析),而基因交流值却达14.50—30.79,群体间K2-P遗传距离为0.0040—0.0056,从而显示大弹涂鱼群体间没有发生明显的地理分化。以Cytb基因序列构建的NJ树揭示4个群体的个体组成2个谱系,但这2个谱系与地理分布并不相关。中性检验、错配分析和网络亲缘关系分析皆表明大弹涂鱼群体有过种群扩张,扩张时间约在更新世末期的0.057—0.023百万年前。

In order to analysis the genetic structure and demographic history of Boleophthalmus pectinirostris, the random amplified polymorphic DNA （RAPD） technology and mitochondrial cytochrome b （Cyt b） gene sequences were used in the study. The results showed that there was high level genetic diversity in the populations ofB. pecinirostris in Yangtze River estuary and its southern wet-land adjacent regions. （1） RAPD was conducted to analysis the genetic variation ofB. pecinirostris in Jiuduansha （JDS）, Dinghai （ DH ） and Xiapu （ XP ） for 20 individuals per population, with 30 polymorphic 10-based random primers selected from 100 ones. In total, 236, 270 and 274 bands were obtained for JDS, DH and XP, respectively and there was 301useful loci. The range of proportion ofpolymorphic loci （P）, Nei＇s gene diversity （H） and Shannon diversity index （I） was： 93.02%-96.3%, 0.3890-0.4219, 0.5618-0.6044, respectively. The results of AMOVA showed significantly genetic differentiation （Fst=0.03004-0.03254, P〈0.05） but there was only 3.2% genetic variation among populations. （2） Results of Cyt b gene： the total Cyt b gene length was 1 141 bp and 33 haplotypes were obtained from 42 individuals collecting in 4 different regions, which included JDS, DH, XP and Cixi （CX）. The average haplotype diversity （h） and nucleotide diversity （π） was 0.9184, 0.0048, respectively. The high level of Nm values （14.50-30.79） and low Fst values （0.0043-0.07814）, the average K2-P distances （0.0040-0.0056）, as well as the AMOVA analysis （total Fst=0.0193, P〉0.05） all revealed that the B. pecinirostris had no obviously geographical differentiation. However, the phylogenetic tree estimated by neighbor-joining （NJ） method indicated that the individuals of B. pecinirostris formed two monophyletic lineages, and the two lineages were not correlated with geographical populations. Neutrality tests, mismatch distribution and network analysis suggested a late Pleistocene population expansion for B. pecinirostris （0.057-0.023 million years ago）.