Patterns of genetic diversity: Stepping‐stone dispersal of an invasive fish introduced by an inter‐basin water transfer project

Abstract

Abstract Knowledge of large‐scale dispersal processes and their associated genetic diversity patterns is significant for managing invasive species. These patterns remain unclear for invasive species that colonise new habitats through inter‐basin water transfer projects. A worm goby Taenioides cirratus colonised several large inland lakes in China, thereby expanding its distribution through the East Route of the South‐to‐North Water Transfer Project (ESNT). Here, we used nuclear microsatellites to analyse patterns of genetic diversity, population structure, gene flow and, invasion history across its native and invasive ranges in China. Our objectives were to: (a) reveal contemporary genetic diversity patterns of T. cirratus in two native and four invasive populations in China; and (b) identify its main model of dispersal in the ESNT. Invasive populations experienced significant loss of genetic diversity because of bottlenecks and low levels of gene flow, and strong population genetic structure due to founder effects that occurred during expansions. Significant genetic isolation‐by‐distance patterns were largely influenced by landscape connectivity and the reduced active dispersal ability of T. cirratus. The one‐way stepping‐stone dispersal model was identified as being most likely for T. cirratus in the ESNT, influenced by the long distance of upstream dispersal and downstream water transfer events. Our results highlight that T. cirratus could overcome low genetic diversity in founding populations, allowing for invasive spread. For management, we suggest physical removal of invasive populations and installation of deterrents near the pump intake area and the lake outflow to reduce further spread in the system. We provided a general paradigm for understanding dispersal patterns involved in inter‐basin water transfers.