基于Rag1基因序列的黄河高原鳅群体遗传结构分析

【目的】明确不同水域黄河高原鳅群体免疫基因多样性水平和遗传组成，为黄河高原鳅自然种质资源现状的评估、保护及合理开发提供理论依据。【方法】采集黄河中上游不同河段的黄河高原鳅自然群体［青海循化（XH）群体、青海大通（DT）群体及甘肃景泰（JT）群体］样品，基于重组激活基因（Rag1）序列对不同黄河高原鳅群体的遗传多样性水平和遗传组成差异进行研究。【结果】在不同黄河高原鳅群体的Rag1基因序列中共检测到8个单倍型（H1~H8），其中有5个单倍型（H1、H2、H3、H4和H6）在2个以上的群体间相互共享，尤其是单倍型H1、H4和H6在所有群体中均有分布。黄河高原鳅总群体的单倍型多态性为0.742，核苷酸多态性为0.003，在3个黄河高原鳅群体中共检测到28个多态位点。不同黄河高原鳅种群间的单倍型多态性范围在0.575~0.872，核苷酸多态性范围在0.002~0.003。XH群体与JT群体间的遗传分化系数（F_st）为0.037，XH群体与DT群体间的F_st为-0.041，JT群体与DT群体的F_st为-0.022；不同黄河高原鳅群体的分子遗传变异主要发生在群体内（占99.56%）。单倍型网络结构图及NJ聚类树和ML聚类树均显示，不同黄河高原鳅自然种群个体相互混合在一起，未按照采样河段地理位置形成明显的聚类结构，即黄河高原鳅不同单倍型间呈现混合的分布格局。【结论】黄河高原鳅群体遗传多样性水平中等，不同自然群体间的遗传多样性水平存在一定差异，但并未检测到显著的遗传差异，建议在野外进行管理和保护时仍可视为一个整体。

Genetic structure of Triplophysa pappenheimi populations based on Rag1 gene sequence

【Objective】Studying the population immune gene diversity and genetic structure could effectively assess the current status，and provide a theoretical basis for conservation and rational exploitation of the wild resources of Triplophysa pappenheimi.【Method】The genetic diversity and structure of the natural populations of T. pappenheimi，sampled from different reaches of the middle and upper reaches of the Yellow River，Xunhua（XH）and Datong（DT）in Qinghai Province，and Jingtai（JT）in Gansu Province，were analyzed by using the recombination activating gene 1（Rag1）sequences.【Result】Eight unique haplotypes（H1-H8） were identified in Rag1 sequence from all individuals of T. pappenheimi. Five haplotypes（H1，H2，H3，H4 and H6）shared between any two of populations，and three of them（H1，H4 and H6）shared among all populations. The haplotype and nucleotide diversities of T. pappenheimi were 0.742 and 0.003， respectively. Twenty eight polymorphic sites were detected in three populations. Haplotype diversity ranged from 0.575 to 0.872 and nucleotide diversity ranged from 0.002 to 0.003 among populations. The genetic differentiation coefficient（Fst） value between XH and JT，between XH and DT，and between JT and DT were 0.037，-0.041，and -0.022，respectively. The molecular variation analysis（AMOVA）revealed high genetic variation within populations（99.56%）. Both NJ and ML phylogenetic tree and haplotype network analysis showed that individuals from different populations were mixed together and did not form obvious cluster according to phylogeographic structure. Mixed distribution patterns were presen ted between the different haplotypes in T. pappenheimi.【Conclusion】It is suggested that these natural populations of T. pappenheimi have the middle level of genetic diversity. Different levels of genetic diversity are found among these wild populations. Moreover，it is not obviously identified genetic divergence among the populations of T. pappenheimi. It is suggested that management and conservation of these populations in the field can be regarded as a whole.