史氏鲟和达氏鳇养殖亲鱼群体遗传多样性分析

Genetic diversity in the reserved parent fish broodstocks of Asipenser schrenckii and Huso dauricus

利用线粒体控制区序列片段(史氏鲟,425bp,达氏鳇,434bp)分析检测了两个养殖场留做后备亲鱼的史氏鲟和达氏鳇的遗传多样性。在所检测的养殖史氏鲟后备亲鱼4个年龄群体共34个体中,发现5个单倍型,共有11个多态位点,占碱基总数的2.6%,无简约信息位点。不同单倍型之间有1～10个变异位点,占碱基总数的0.2%～2.4%。各单倍型之间的遗传距离为0.002～0.024。单倍型多样性Hd=0.768,平均核苷酸差异数k=4.367,核苷酸多样性Pi=0.011。而分别来自2个养殖场的2个达氏鳇养殖群体都是1个群体仅1个单倍型,2个单倍型之间仅有2个碱基差异,遗传距离为0.005,遗传变异极度缺乏。结果提示在利用史氏鲟和达氏鳇后备亲鱼进行繁殖育苗时要充分注意近交的影响。

Germplasm degradation caused by inbred is an important problem that should be avoided during fish fry production in aquaculture. The inbred risk may be more severe in fry production of Amur sturgeon Asipenser schrenckii and Kaluga Huso dauricus because of their late maturation,rare mature fish resource and the ability to reproduce a large amount of eggs at one time. The present work examined the genetic diversity of 4 Amur sturgeon and 2 Kaluga reserved parent fish boodstocks from two hatcheries,using mitochondrial control region（D-loop） fragment sequence（Amur sturgeon 425 bp;Kaluga 434 bp（as the molecular marker. A total of 5 haplotypes were detected among 34 individuals from 4 Amur sturgeon stocks. There were 11 polymorphic sites,accounted for 2. 6% of the total sites,no parsimony-informative sites. There were 1-10 variable size among different haplotypes,accounted for 0. 2%-2. 4% of the total sites. Genetic distance among these haplotypes varied from 0. 002-0. 024. The haplotype divergence,average number of nucleotide differences and nucleotide divergence were 0. 768,4. 367 and 0. 011,respectively. There was only one haplotype for each Kaluga stock from the two different hatcheries. Genetic difference between the two Kaluga haplotypes was 0. 005,indicating a marked low genetic difference in Kaluga reserved parent fish broodstocks. These results show that much attention should be paid to avoid the inbred risk in sturgeon fry production,especially for Kaluga.