华南6水系与澜沧江-湄公河攀鲈线粒体ND2基因的遗传多样性分析

MtDNA ND2 sequence-based genetic analysis of Anabas testudineus from South China and Lancang/Mekong River

测定了中国华南6水系及澜沧江(云南勐腊)-湄公河流域(柬埔寨洞里萨湖)的125尾攀鲈(Anabas testudineus)线粒体部分ND2基因1 010 bp序列,分析发现39个变异位点和12个单倍型,总遗传多样性较低(h=0.369,π=0.003 8),推测可能经历过严重的瓶颈效应;中国攀鲈群体遗传多样性更低(h=0.282,π=0.000 4),处于边缘区的中国攀鲈群体是造成低遗传多样性的主要原因。在单倍型网络图中柬埔寨和中国攀鲈各自聚类,具有明显地理结构和谱系结构,推测地质运动和气候变化导致基因交流受阻所致。核苷酸错配图和中性检验表明中国群体经历过种群扩张,时间约为(5.94~4.13)万年前。华南水系群体间基因交流通畅,不存在明显分化;但与云南澜沧江群体间分化大而显著(FST=0.775,P<0.01),AMOVA分析显示变异主要来自组群间(77.41%),推测二者分化时间约为(4.0~2.8)万年前,云南群体受末次冰期的影响,基因交流受阻而出现分化。中国群体和柬埔寨群体可作为2个管理单位进行保护;就中国群体而言,韩江水系群体遗传多样性最高,建议优先保护;澜沧江与华南水系间群体分化显著且遗传多样性极低,建议对澜沧江水系群体进行保护,以避免种质资源灭绝。

The 1 010 bp mtDNA ND2 sequences of 125 individuals ofAnabas testudineus collected from six basins in South China and Lancang（ Mengla, Yunnan Province, China）/Mekong Rive （Tonle Sap Lake, Cambodia） were used to investigate the genetic back- ground in China. The results found 39 variable sites and 12 haplotypes with relatively low genetic diversity （h = 0. 369, π = 0. 003 8 ）, which suggests a serious bottleneck effect. Being a peripheral population, the China group had much lower genetic diversity. The pairwise fixation index （FST =0. 987, P 〈 0. 001 ） and net genetic distance （0. 027 9） between the distinct Cambodia group and China group indicates remarkably high population differentiation. The geology movement and climatic variation might have resulted in geographic isolation and allopatric distribution. Both nucleotide mismatch distribution and neutrality tests show that A. testudineus in China experienced population expansion and the time might be 59.4 -41.3 ka BP. No obvious genetic differentiation was found in the populations from six basins in South China. However, remarkable genetic differenliation was found between South China populations and l,ancang River population （Fsy = 0. 775, P 〈 0. 001 ）. Analysis of molecular variance （AMOVA） also reveals that most of genetic variation existed among groups （77.41%） , and the deduced differentiation time was approximately 40 -28 ka BP, which might be caused by dramatic climatic changes and impassable physical harriers duriug the last glacial period （32 - 16 ka BP）. The China group and Ca,nbodia group are two management units. As for China group, Han River population should have a priority to be protected for its more genetic variability; Lancang River population also should he protected for its significant population differentiation with the other South China basins and for its lowest genetic diversity.