Dispersal patterns of Dreissena bugensis in the Laurentian Great Lakes as inferred from highly polymorphic microsatellite markers
The freshwater Dreissenidae are well suited for rapid dispersal, retaining a primitive form of planktotrophic development and a capacity to produce byssal threads, both of which may have accelerated their spread through North America. In contrast to the radiation of Dreissena polymorpha, which has been characterized by several jump dispersal events, D. bugensis has exhibited a more gradual diffusion from its point of introduction in Lake Erie through the lower Laurentian Great Lakes. In this thesis, I develop six highly polymorphic species-specific microsatellite markers and use these markers to examine the present-day population genetic structure of D. bugensis in North America. Data suggest that, in contrast to census data suggesting diffusive dispersal of D. bugensis, high levels of gene flow have been maintained between geographically disjunct populations, presumably due to boater-mediated transport of adult mussels. At the same time, more proximate populations are significantly different, indicating non-random settlement of veliger larvae. These results suggest that divergent dispersal strategies have played an important role in the success of the quagga mussel invasion.