Population genetics of Melampus bidentatus (Gastropoda: Pulmonata): the effect of planktonic development on gene flow

Melampus bidentatus has restricted gene flow of gametes and the potential for extensive gene flow of their planktonic larvae. We used genetic data to examine the influence of these opposing forces on the population structure of six Delmarva Peninsular populations. We analyzed the population structure of these six populations using twenty-three electrophoretic loci. Two ocean populations gave the appearance of large panmictic populations, while the other four populations appeared to be highly subdivided due to either restricted gene flow or age-structuring of the population. Two distinct groups of populations are apparent, which accounts for the extreme interpopulation heterogeneity. These data suggest that the direction of tides and currents limit the effectiveness of the planktonic dispersal stage of M. bidentatus in overcoming restricted gene flow of gametes.