拉氏鱥mtDNA COI区段的遗传多样性分析

Genetic diversity analysis of mtDNA COI region in Phoxinus lagowskii

为了检测拉氏鱥的遗传多样性以及不同体质量的个体间是否存在遗传差异,选取同时间人工繁殖、同池养殖的体质量不同的40尾拉氏鱥,对其线粒体DNA COI区段进行PCR扩增,测序后获得碱基顺序排列清晰的1 551~1 552 bp DNA片段. 40尾拉氏鱥可分为23种单倍型,共有128个位点存在碱基差异.依据单倍型间Kimura 2-parameter遗传距,可将23种单倍型分为类型1和类型2.类型1中37尾拉氏鱥含20种单倍型(Ⅰ~XX),Kimura 2-parameter遗传距范围为0.000 00~0.005 84;类型2中3尾拉氏鱥含3种单倍型(XXⅠ~XXⅢ),遗传距范围为0.001 29~0.003 23;类型1各单倍型和类型2各单倍型间的遗传距范围为0.073 75~0.080 48. 2种类型间的遗传差异明显,可以初步认为其亲本来自2个不同的物种.类型1中的大、中、小不同体质量的拉氏鱥组内、组间遗传距在0.001 23~0.001 97之间,不同体质量的个体间未见明显的遗传差异.类型1拉氏鱥的单倍型多样性指数(Hd)、核苷酸多样性指数(Pi)及平均核苷酸差异性(k)分别为0.862、0.001 71和2.646,类型2拉氏鱥的H_d、P_i和k分别为1.000、0.002 58和4.000.类型2拉氏鱥的遗传多样性略高于类型1的多样性.

In order to detect the genetic diversity of Phoxinus lagowskii and the genetic differences among individuals with different body mass,40 individuals of Phoxinus lagowskii with different body mass breeded in same time and environment were sampled,and the mtDNA COI region of which were amplified by PCR. After sequencing analysis,DNA fragments with clear base sequence arrangement were obtained,and the lengths were 1 551-1 552 bp. 40 individuals included 23 haplotypes,and128 locations had base difference. According to Kimura 2-parameter genetic distance,the 23 haplotypes can be divided into type 1 and type 2. The Kimura 2-parameter genetic distance among 20 haplotypes (Ⅰ-XX)of type 1 including 37 individuals ranged from 0.000 00 to 0.005 84,and the genetic distance among 3 haplotypes(XXⅠ-XXⅢ)of type 2 including 3 individuals ranged from 0.001 29 to 0.003 23. The genetic distance among haplotypes of type1 and type 2 ranged from 0.073 75 to0.080 48. Because the genetic difference in two types was distinct,it is speculated that the parents of 40 individuals came from two different species. The genetic distance within or among three groups of large,middle and small individuals in type 1 of Phoxinus lagowskii ranged from 0.001 23 to 0.001 97,which demonstrated that the genetic difference among three groups with different body mass was not obvious. The haplotype diversity(Hd),nucleotide diversity(Pi)and mean of nucleotide differences(k) in type 1 were 0.862,0.001 71 and 2.646 respectively,and the H_d,P_i and k in type 2 were 1.000,0.002 58 and 4.000 respectively. The genetic diversity of type 2 was slightly higher than that of type 1.