Authors: Tsz Huen Wu, Simon Kin Fung Chan, I-Shiung Chen, Tony King Tung Chan and Ka Hou Chu
Population genetic studies in combination with geological records provide insights on the forces that may influence population differentiation and current geographic distribution of taxa. Many phylogeographic studies on freshwater fishes have demonstrated the roles of immense geographical barriers and global historical events in shaping the genetic structure of freshwater fishes, but little investigations have been made on how regional landscapes, such as physical barriers or river network affect genetic differentiation of fishes.
In the current study, we investigated the genetic diversity and population differentiation of an indigenous freshwater fish species, the Broken-band Hillstream Loach Liniparhomaloptera disparis in Hong Kong. Phylogenetic analyses on over 100 individuals collected from 27 localities revealed a moderate yet significant genetic structuring of L. disparis resided in Hong Kong. Three major haplotype groups are recovered. Groups 1 and 2 are widely distributed in the New Territories, while group 3 is endemic to Lantau Island. Population subdivision is evident between haplotype groups 1 and 2. The observed population structure on a small spatial scale is probably attributed to the local landscapes such as the mountain ranges located in the New Territories and the poorly connected hill streams. Owing to the strong association of L. disparis to regional landscape and evident population differentiation in Hong Kong, we suggest that the sampling of freshwater fish for population genetic analysis has to be conducted on a fine spatial scale, in order to reveal a complete evolutionary history of freshwater fishes.
Keywords: Population genetics, Freshwater biology, fish