Investigation On The Fish Resources And Genetic Diversities In The Upper Reaches Of Yunnan Section Of Lancang River

In recent years,a series of cascade hydropower stations have been planned and constructed in the upper reaches of Lancang River in Yunnan.In order to discuss the effects of the cascade hydropower stations on the fish resoueces and genetic diversities in the river section,investigations were conducted on the fish resources of 7 waters from Wunonglong to Gongguoqiao,and the genetic diversities of two representative fish species,Glyptothorax longinema and Triplophysa brevicauda based on the full sequences of mitochondrial DNA D-loop（mt DNA D-loop）.The aim of the present study was to provide some basis for the coordinated development of the fish resource protection and hydropower development in this river section.The main results were as follows:（1）The fish resource status in the upper reaches of Yunnan section of Lancang River.The results of the investigation on the fish resources showed that 28 species in 3orders,8 families,10 sub families,23 genera,3 subgenera were identified.Among this fishes,Cypriniformes was the dominant fish resource in the river section,which proportion was more than 75 per cent;three species,Schizothorax lissolabiatus,Glyptothorax longinema and Triplophysa brevicauda were the dominant species.The average Shannon-Wiener index,richness index,evenness index and Simpson’s index were 2.996,1.46,0.43 and 0.75,respectively.This river section was rich in fish resources,the main fish species remain relatively stable after the constrution of the hydropower stations,but the exotic species were on the rise.（2）Genetic diversity of Glyptothorax longinema based on the full sequences of mt DNA D-loop.The full length of mt DNA D-loop sequence of Glyptothorax longinema was 927 bp,which the content of A+T and C+G was 64.8 and 35.2 per cent,respectively.There were 58 polymorphic mutation sites and formed 50 haplotypes.Among the haplotypes,eleven were shared and thirty-nine were unique,which the number of unique haplotypes of the population Gushui,Wunonglong,Tuoba,Huangdeng and Miaowei were3,19,5,8 and 13,respectively.The haplotype diversity index（H_d）,nucleic acid diversity index（π）and genetic differentiation index(F_st)were 0.966（0.889-0.987）,0.0085（0.0038-0.0076）and 0.3341（P<0.01）,respectively,which indicated that the genetic diversity of Glyptothorax longinema was maintained good in the upper reaches of Yunnan section of Lancang River,but significant genetic differentiation has occurred between some populations.It might be inferred that the cascade hydropower stations might have played a certain driving role in the genetic differentiation.（3）Genetic diversity of Triplophysa brevicauda based on the full sequences of mt DNA D-loop.The full length of mt DNA D-loop sequence of Triplophysa brevicauda was 921 bp,which the content of A+T and C+G was 65.29 and 34.71 per cent,respectively.There were 22 polymorphic mutation sites and formed 21 haplotypes.Among the haplotypes,eleven were shared and ten were unique,which the number of unique haplotypes of the population Wunonglong,Lidi,Tuoba and Miaowei were 2,3,4 and 1,respectively.The values of H_d,πand F_stwere 0.906（0.837-0.942）,0.0054（0.0052-0.0057）and 0.0213（P>0.05）,respectively,which indicated that the genetic diversity of Triplophysa brevicauda was rich in the upper reaches of Yunnan section of Lancang River,and no obvious genetic differentiation occurred between different populations.