基于线粒体D-loop的西江流域粗唇鮠群体遗传多样性分析

Population genetic diversity analysis of Leiocassis crassilabris in the watershed of Xijiang river base on mitochondrial D-loop

为研究西江流域粗唇鮠(Leiocassis crassilabris)种群遗传多样性,以采自西江流域7个不同江段的227尾粗唇鮠为样品,采用PCR与DNA测序技术,获得7个江段粗唇鮠线粒体D-loop序列长度为666 bp,碱基T、C、A、G的平均含量为32.9%、23.3%、29.4%、14.4%,A+T(62.3%)明显高于C+G(37.7%)。7个江段群体的遗传多样性处于较低水平,整个群体单倍型多样性指数为0.05224,核苷酸多样性指数为0.00011,其中,均以西江群体最高,分别为0.19951、0.00052,都柳江、柳江、郁江和左江群体最低,均为0.00000,整体呈现下游高于上游,南方高于北方的现象。NJ系统树表明本次调查的粗唇鮠群体拥有6种单倍型。群体间表现出很小的遗传分化,Fst为-0.01062~0.01977。AMOVA分析结果显示,变异几乎全部来自种群内部,其中不同江段群体间的变异占0.13%,群体内部占99.87%。动态历史分析结果表明,西江流域广西段粗唇鮠的有效种群可能是在距今0.75~1.25 Ma前由单一、少数种群所产生,西江流域粗唇鮠种群遗传多样性较低。

Mitochondrial D-loop gene from seven different sections with 227 individuals of Leiocassis crassilabris were measured by PCR and DNA sequencing techniques to study the population genetic diversity of this species in the watershed of XiJiang river.The length of mitochondrial D-loop sequence was 666 bp,and the average content of essential T,C,A and G was 32.9%,23.3%,29.4%and 14.4%in seven different river populations,respectively.The primary groups A+T(62.3%)was significantly higher than C+G(37.7%).The genetic diversity of seven groups was at a low level.The diversity index about haplotype and nucleotide of the whole population was 0.05224 and 0.00011,respectively.Xijiang population had the highest haplotype and nucleotide diversity index,which was 0.19951 and 0.00052,respectively.While the Duliujiang,Liujiang,Yujiang and Zuojiang populations had the lowest diversity index(0.00000).The results showed the regulation that the diversity index at downstream was higher than that at upstream.The south group was higher than the north group.NJ system tree showed that there were six haplotypes of L.crassilabris in Xijiang River Watershed for this survey.Seven groups at different rivers showed minimal genetic differentiation with Fst ranged from-0.01062 to 0.01977.AMOVA analysis indicated that the variation of L.crassilabris in this investigation almost came from group internal when the different group accounted for 0.13%,and within the group accounted for 99.87%.The results of dynamic history analysis indicated that the active population of L.crassilabris in this investigation might be generated from a single or a few populations before 0.75-1.25 Ma.The genetic diversity of L.crassilabris populations in this research was much lower than the most other fishes living in the same water area at present.