Population genetics of a Chinese endemic, Gymnocypris potanini Herzenstein, threatened by population isolation: conflicting patterns between microsatellites and mitochondrial DNA

Freshwater fish population isolation is concerning considering few major rivers are undammed. Key prerequisites for scientific genetic management of threatened species are genetic diversity and population structure information. Population genetic analyses based on microsatellites and mtDNA control region were conducted in Gymnocypris potanini, an endangered Chinese endemic schizothoracine fish in the Tibetan Plateau. The results showed that three populations from the dammed Zagunao River possessed higher levels of microsatellite diversity than three other populations in different, but nearby, dammed river systems. However, mitochondrial data showed the lowest variability in Zagunao populations and neutrality tests were significant. The relatively low mtDNA variability and the relatively high nuclear variability might be explained by selective sweep in Zagunao populations. Isolation might have already influenced the genetic divergence of Zagunao populations considering the highly significant FST values (P < 0.001). Microsatellite data of Zagunao populations could be used as a baseline for investigating changes in genetic status of the separated populations given the ongoing operation of the hydroelectric projects. It appears that geologic isolation influenced the distribution and evolution of G. potanini in the Tibetan Plateau, which may benefit predictions of genetic changes to anthropogenic-caused separation in the future.