黄河上游极边扁咽齿鱼种群遗传结构

极边扁咽齿鱼Platypharodon extremus是黄河上游的特有鱼类,近年来由于过度捕捞、环境变迁等因素,其资源量剧减,种群处于濒危状态。研究中采集了分布于黄河上游的3个种群（n=107）,基于线粒体DNA控制区695bp序列,共检测到101个可变位点,占总分析位点的14.5%,其中58个为简约信息位点。3种群共界定了87个单倍型,种群平均单倍型多样性h=0.995,核苷酸多样性π=0.0129。结果表明,极边扁咽齿鱼的种群遗传多样性水平较高。分子方差分析（AMOVA）表明,3群体间总遗传分化系数Fst=0.0528,群体间尚未有显著的遗传分化。系统发生树显示3种群的单倍型混合分布,各进化枝之间分歧度很低,没有形成明显的单倍型组,也没有显示出单倍型与地理位置的对应关系。3个群体共享1个单倍型（Hap₃1）,推测它们来自于共同的祖先。歧点分布和Fu’Fs中性检测显示极边扁咽齿鱼并未经历种群扩张。

POPULATION GENETIC STRUCTURE OF ENDANGERED SPECIESPLATYPHARODON EXTREMUS (SCHIZOTHORACINAE, CYPRINIDAE) IN YELLOW RIVER, CHINA

Platypharodon extremus is one of an endemic Schizothoracin fishes and historically was distributed in several headwater streams of the Yellow River in the Northeastern Qinghai-Tibetan Plateau. With the intensification of human activities, habitat destruction / alteration, water pollution and overexploitation, the wild populations of this species have rapidly declined in recent years and its distribution has been drastically reduced. Now mainly distributed in the upper reach of the Yellow River on the hinterland of the Qinghai-Tibet plateau in Western China. And it was listed as endangered species in the "China Red Data Book (Pisces)", Vulnerable (V) by the National Environmental Protection Agency and Endangered Species Scientific Commission. To assess the genetic diversity, population structure and demographic history of P. extremus, three populations including 107 individuals from the upper reaches of the Yellow River were investigated based on 695 bp nucleotide sequences of mtDNA partial control region. The sequences analysis results showed that only 101 variable sites in the sequences (14.5 %), including 58 parsimony informative sites. In the total 107 sequences, 87 haplotypes were detected, the haplotype diversity (h) and nucleotide diversity (π) were 0.995, 0.0129 respectively. Analysis of molecular variance (AMOVA) revealed that genetic variation within the populations was 5.28 %, among the populations was 94.72 %. Phylogenetic analysis failed to detect significant geographic structure. Mismatch distribution and neutrality tests indicated that P. extremus in this research hadn’t experienced population expansion.