TEMKIN, M.H.*; TWICHELL, N.P.; ERICKSON, J.M.; St. Lawrence University, Canton, NY; St. Lawrence University, Canton, NY; St. Lawrence University, Canton, NY: Contemporary gene flow and historic events have produced geographic associations of genetic variation in populations of the freshwater mussel Elliptio complanata from northern New York

The Adirondack Highland and adjacent St. Lawrence Lowland areas of New York represent a potentially important postglacial suture zone for freshwater invertebrates that has been understudied. After deglaciation, drainage connections in this region joined the Interior Basin to the Atlantic Slope. Subsequently, significant geomorphic rearrangements of ancient waterways formed the eight rivers that are presently draining the Adirondacks. This geomorphic activity may have also fragmented existing freshwater invertebrate populations, including those of the freshwater mussel Elliptio complanata. In this study Nested Clade Phylogeographic Analyses (NCPA) of maternal mitochondrial gene sequences (cytochrome C oxidase subunit I and 16s rRNA) were used to discriminate between geographic associations of E. complanata genetic diversity due to contemporary restrictions on gene flow by interpopulation distances and historic population events, such as fragmentation and range expansion. In addition, coalescent based analyses using Baysian inference were used to estimate relative migration and divergence times between E. complanata populations of the Oswegatchie and Grass Rivers, two drainages that have been historically interconnected. The results of NCPAs indicate both restricted gene flow and range expansion may have been important in establishing the current geographic patterns of E. complanata genetic diversity in northern New York. Coalescent based analyses suggest that patterns of genetic variation within and between the Oswegatchie and Grass Rivers may reflect ancient drainage patterns.