鳙中国土著群体与移居群体遗传变异的AFLP分析

Genetic variation of bighead carp Aristichthys nobilis from Chinese native populations and introduced populations by AFLP

为全面了解鳙(Aristichthys nobilis)在世界范围的群体遗传状况,本研究采用AFLP技术分析了鳙中国土著群体(长江、珠江)与国内、外移居群体(中国黑龙江、欧洲多瑙河、北美密西西比河)的遗传变异特征,结果表明,鳙长江、珠江土著群体的Nei’s基因多样性(H)分别为0.0394±0.1221和0.0529±0.1236,黑龙江、多瑙河、密西西比河移居群体分别为0.0233±0.0883、0.0122±0.0619和0.0134±0.0614,说明国内、外移居群体的遗传多样性显著低于国内土著群体,这与移居群体的来源以及在异地适应、定居、建群过程中发生了明显的遗传瓶颈效应有关。AMOVA分析表明,群体间差异对群体总遗传变异的贡献率为31.48%,而群体内的贡献率为68.52%。鳙长江、珠江群体间的遗传分化指数Fst值为0.3501(P<0.01),土著群体与国内、外移居群体间的总Fst值为0.1550(P<0.01),鳙土著群体与国内、外移居群体间表现为显著分化,反映了移居新形成的自然群体在遗传背景、遗传漂变、经历的生态环境压力与自然选择等方面与土著群体间存在明显差异。本研究通过了解鳙自然群体的遗传现状,海内、外移居群体与中国土著群体的遗传差异,旨为进一步监测该物种海内、外移居群体的遗传变化趋势积累资料,为鳙遗传资源保护、引种移植管理提供依据。

Bighead carp,Aristichthys nobilis,one of the largest economical cyprinids species,is endemic in eastern China plains,and has also formed some new populations in alien rivers due to extensive introduction for aquacultural or ecological purposes.To understand the genetic resource of wild bighead carp around the world,genetic variation of Chinese native populations from Yangtze River （YZ） and Pearl River （PR）,national introduced populations from Amur River （AMUR）,and two alien introduced populations from Danube River （DAU）,Europe,and Mississippi River （MIS） and North America were analyzed by AFLP.The results showed Nei＇s genetic diversity （H） of the native populations YZ and PR were 0.0394±0.1221 and 0.0529±0.1236,respectively,while 0.0233±0.0883,0.0122±0.0619 and 0.0134±0.0614 for the introduced AMUR,DAU and MIS populations.Genetic diversity of the introduced populations was lower than the native populations because continuous genetic bottle-neck effects happened for the introduced populations during the progresses of introduction,adaption and establishment of new populations in alien areas.AMOVA showed the variance within populations was 68.52% while interpopulations variance was 31.48% for all bighead carp populations.The Fst of two native populations was 0.350 1 （P0.01）,while Fst of native populations and introduced populations was 0.155 0 （P0.01）.There was significant difference among native populations and introduced populations,which may reflect different genetic background and genetic drift,ecological pressure and natural selection exerted on them.The above results may be helpful to monitor genetic variation trends for both native populations and introduced populations in alien rivers in the future.