No decline of genetic diversity in elongate loach (Leptobotia elongata) with a tendency to form population structure in the upper Yangtze River

Elongate loach (Leptobotia elongata) is an endemic fish distributed in middle and upper reaches of the Yangtze River in China. The genetic diversity and population structure of twelve populations of the species collected before (2008) and after dam constructions (2014–2015) on lower reaches of the Jinsha River were investigated using mtDNA control region and nuclear microsatellite DNA markers. The allelic richness (Ar) within populations varied from 11.06 to 15.25. Average polymorphic information content (PIC) ranged from 0.796 to 0.863. Haplotype diversities (h) ranged from 0.873 to 0.902, nucleotide diversity (π) ranged from 0.0030 to 0.0047. No significant differences of genetic diversities were identified between populations collected in 2008 and 2014–2015. The genetic differentiations (Fst) among the five populations (LUA, CQ, PZH, BX and NX) collected in 2008 were all insignificant, while that among some populations (JPD and CQ or GC, and GLP and NX or WS) collected in 2014–2015 were significant based on microsatellites. Negative correlations between the genetic diversities and geographical elevations for the seven populations collected in 2014–2015 indicated that the populations of L. elongata in high elevation regions were more vulnerable than that in low elevation regions. The results in the present study showed that no decline of genetic diversity occurred in L. elongata after dam constructions on lower reaches of the Jinsha River, while genetic structure of the populations between upstream and downstream of the dams tended to be formed. Translocating wild individuals of the populations between dams is suggested to enhance the gene flow and prevent potential genetic declines and isolations in L. elongata.