基于Cyt b基因的雅鲁藏布江中下游巨须裂腹鱼种群遗传多样性研究OA

Schizothorax macropogon is a cold-water fish endemic to the Qinghai-Tibet Plateau in China.It is only distributed and is also one of the main economic fish in the Yarlung Zangbo River Basin,occupying an impor-tant position in the local fishery economy.Nowadays,it is classified as a Class II protected animal in China.Guo Xiangzhao′s genetic diversity study based on the Cyt b gene showed that S.macropogon had high genetic diversity 10 years ago.With the habitat destruction caused by human activities,invasion of alien species,hydropower development and other factors,the natural population resources of S.macropogon had sharply decreased current-ly.At present,there was no research on the genetic diversity of the extant natural population of S.macropogon in the Yarlung Zangbo River,so it was difficult to accurately evaluate the survival ability and adaptation potential of S.macropogon,which also seriously restricted the in-depth understanding of the resistance stability of the eco-system.Therefore,it was necessary to study the genetic diversity of S.macropogon in order to better understand its natural resources,reveal its survival ability and adaptive mechanism,and providing scientific basis and protec-tion strategies for the subsequent population rejuvenation of S.macropogon.In this study,the mitochondrial Cyt b gene sequences were used to analyze the genetic diversity of 155 samples of S.macropogon from eight geographic groups in the middle and lower reaches of the Yarlung Zangbo River.The results showed that S.macropogon had 40 polymorphic loci and 33 haplotypes,with the overall haplotype diversity(Hd)of 0.792 and nucleotide di-versity(Pi)of 0.00184,which showed a decreasing level of genetic diversity compared with that of 10 years ago.The results of phylogenetic tree and haplotype network map constructed based on the maximum likelihood method were consistent,and the genetic distances among the eight populations were all below 0.003,and the populations did not form an obvious geographical distribution pattern.The Fst values of genetic differentiation coefficients among the geographic groups ranged from-0.01941 to 0.122 59,and the genetic differences a-mong the groups were small and the genetic differentiation phenomenon was not obvious,except between the RiCun(RC)group and the other groups,which indicated that there was a frequent exchange of genes among the groups.Analysis of Molecular Variance(AMOVA)showed that 96.97%of the genetic variation was gener-ated among individuals within the population.The combined results of the neutrality test,mismatch distribution analysis,and Bayesian skyline analysis indicated that the S.macropogon population had recently undergone a population expansion event and had a complex evolutionary history.The genetic diversity of the S.macropogon population is relatively low and decreasing,and reasonable management measures are urgently needed to strengthen the resource conservation and restoration of S.macropogon in the Yarlung Zangbo River Basin.