不同地理群体裸体方格星虫遗传结构及种群分化研究

Genetic structure and population differentiation of Sipunculus nudus in China based on sequence analyses of mitochondrial COI gene

本研究对福建长乐、古雷、晋江海区裸体方格星虫自然群体91个个体的线粒体COI基因进行序列测定,并与厦门、北海、三亚3个地理群体15个个体的线粒体COI基因序列进行了比较分析。在106个个体中共发现193个核苷酸多态位点和52个单倍型,长乐、古雷、晋江海区3个地理群体中单倍型多样性指数(h)在0.626到0.972之间,核苷酸多样性(π)在0.00155到0.01325之间,表现出较高的遗传多样性。分子方差分析(AMOVA)显示1.97%的变异存在于群体内,而群体间的遗传变异为98.03%,群体间变异是总变异的主要来源。构建的单倍型系统关系树显示单倍型聚合为A、B、C、D 4个不同的具有高支持率的分支,表明我国沿海至少存在4个线粒体具显著差异的类群,并可能存在隐蔽种。单倍型最小拓展网络图揭示裸体方格星虫类群A存在福建沿海和北部湾两个明显的分支,是否可提升为亚种有待进一步考证。研究结果为中国沿海裸体方格星虫种质资源保护、人工苗种放养及遗传育种工作的开展提供了依据。

Genetic structure and population differentiation in wild populations of Sipunculus nudus were researched in this paper.91 samples collected from Changle、Gulei、Jinjiang in Fujian province and 15 from Xiamen、Beihai、Sanya were studied based on sequence analyses of the mitochondrial cytochrome oxidase I（mtDNA COI） gene segment.193 nucleotide polymorphisms and 52 haplotypes were found in total 106 samples.Among three Fujian geographical groups,gene diversities（π） ranged from 0.00155 to 0.01325,and the nucleotide diversities（h） from 0.626 to 0.972,showed that Sipunculus nudus had high genetic diversity.AMOVA analysis disclosed that variation among populations accounted for 98.03% of total variation,revealed that variations occurred between populations were the main source of the total variation.Neighbor-joining tree based on mtDNA COI sequence showed A、B、C and D,the four different branches with high support value.The four distinct clades among south China coastal waters revealed underestimate cryptic diversity within Sipunculus nudus.Minimum spanning network from all haplotypes revealed two distinct branches as Fujian and the northern Gulf in groups A,which might be approached to subspecies level upon further research.This study would be useful for the resources protection,artificial seed stocking and genetic breeding of Sipunculus nudus.