Impact of Hydropower Development on the Genetic Diversity and Population Structure of Schizothoracine Fishes on the Qinghai-Tibet Plateau

[1]¿p#1 newcommands Hydropower development significantly impacts river connectivity and threatens the sustainability of freshwater fish populations. To evaluate its genetic consequences, we studied the mitochondrial cytochrome b gene in two economically important species, Schizothorax waltoni and Schizothorax macropogon, from three sites in the Yarlung Zangbo River, where large-scale hydropower projects have been implemented. A total of 576 individuals were analyzed, revealing high haplotype diversity (Hd > 0.5) but low to moderate nucleotide diversity (Pi < 0.007). Genetic differentiation was low (Fst < 0.01) among most populations, and Bayesian clustering revealed significant gene flow, particularly between previously isolated populations. Notably, the historical genetic differentiation between the Sangri (SR) and Mainling (ML) populations of S. waltoni, once separated by a natural waterfall barrier, has been eliminated since the operation of the Zangmu Dam, indicating rapid human-mediated genetic homogenization. Despite these changes, deep evolutionary lineages persist, highlighting the long-term biogeographic history of the species. These findings underscore the capacity of human activities to alter genetic structures rapidly, while preserving deeper evolutionary lineages. Our results provide valuable genetic insights for fishery management under hydropower development, advocating for genetic monitoring, habitat restoration, and lineage-based conservation strategies in plateau river ecosystems.