Applying genetic tools to investigate grass carp invasiveness

Grass carp (Ctenopharyngodon idella) were introduced to the United States in 1963 for use in aquaculture to control aquatic vegetation. After their introduction, grass carp escaped into the wild and spread rapidly via natural reproduction. Grass carp alter aquatic ecosystems by modifying habitat structure, initiating trophic cascades, and ultimately threatening native fishes. Studying basic population genetics of this species could help us understand why they are successful invaders and help to prevent further spread of the species. Microsatellite markers are a useful tool for characterizing population genetics, but markers for grass carp have only been developed and tested in fish collected from their native range. Polymorphic microsatellites in grass carp collected in the US will be used to estimate population parameters and develop demographic models for this invasive species. We tested forty-one available markers, and found thirty-one to be polymorphic in grass carp collected in the United States.  For future study, high-throughput sequencing using these markers will be applied to obtain genetic data. Demographic models based on the microsatellite data will be used to develop predictions about the mechanisms driving invasion success in novel habitats.  These predictions may help inform best management practices for invasive species, particularly Asian carps.