中国达氏鳇野生群体和两个养殖群体的线粒体遗传多样性分析

Mitochondrial DNA genetic diversity in the wild and two cultured Kaluga(Huso dauricus) populations in China

达氏鳇(Huso dauricus)是黑龙江流域土著鲟,近几十年来野生资源急剧下降,被确定为濒危物种之一。本研究采用线粒体DNA的Cyt b基因和D-loop区域的多态性信息评估了黑龙江抚远段野生群体、北京房山国家级鲟鱼原种场的保种群体及浙江衢州国家级鲟鱼良种场的繁殖群体等3个达氏鳇群体的遗传多样性水平。所有测试个体在Cyt b基因位点的核苷酸水平上没有检测到多样性,均具有相同的Cyt b单倍型,而在D-loop区域中发现了9种单倍型,对于D-loop区,单倍型多样性(H_d)达到0.593,但核苷酸多样性(π)仅为0.00213。在8尾野生个体中检测到6种D-loop单倍型,2个养殖群体共计58尾个体共计检出5种D-loop单倍型个体。分析结果显示:野生达氏鳇群体遗传多样性极低,历史上可能经历过严重的遗传瓶颈,同时达氏鳇人工繁殖过程中每批次可能只有极少个体参与了繁殖。此外,基于Cyt b基因部分序列的分析结果提示,达氏鳇与其他太平洋鲟类的亲缘关系较近,而与欧鳇(Huso huso)关系较远,传统上鳇属(Huso)的分类地位得不到有效的分子生物学数据支持。

Kaluga(Huso dauricus)is the native sturgeon in the Amur river.Similar to other sturgeons,their populations have sharply decreased in recent decades;they have been identified as one of the most endangered species in the world.Unlike the rapid decline of wild populations,sturgeon farming has rapidly increased in China Mainland.The intra-specific hybridization of the female Kaluga and male Amur sturgeon(Huso dauricus♀×Acipenser schrenckii♂)is widely performed,constituting a large part of sturgeon production in China.In this study,we use the Cyt b gene and D-loop region of mitochondrial DNA to assess the genetic diversity of three Kaluga populations,including the wild population from the Amur river,and two populations cultured in national sturgeon breeding farms located in China:one from Fangshan,in Beijing city and the other from Quzhou,in the Zhejiang province.All of the tested individuals were of identical the Cyt b haplotype,whereas 9 haplotypes were found in the D-loop region.There was no diversity detected at the nucleotide level on the Cyt b gene locus.For the D-loop region,haplotype diversity(Hd)reached 0.593,but nucleotide diversity(π)was only 0.00213.There were 6 D-loop haplotypes detected in 8 individuals from the wild population and 5 haplotypes detected in 58 individuals from the cultured populations.The results suggested the wild Kaluga population might have experienced a serious genetic bottleneck.Meanwhile,in the process of artificial propagation of Kaluga,only a few individuals might have been involved in reproduction each time in both the cultured populations.Phylogenetic tree analysis based on partial sequences of the Cyt b genes supported the previous results from other researchers.The phylogenetic relationship between Huso dauricus and other Pacific sturgeon species was close,but that between Huso dauricus and Huso huso was not.Our result implied that the prevalence of the traditional Huso genus was not supported by molecular genetic data.