Mapping the hypotelminorheic habitat by studying the population structure of amphipods in seeps

The hypotelminorheic is a type of perched aquifer with an unknown geographic extent. Depending on the local topography, groundwater from one hypotelminorheic may flow to the surface forming a single seep, or to several surface locations forming multiple seeps. In order to infer the boundaries of the hypotelminorheic, I analyzed the population structure of a subterranean seep amphipod species. I analyzed a 628 bp region of mtDNA corresponding to the cytochrome oxidase c subunit I gene from 118 specimens of S. tenuis potomacus , collected from 9 seeps along the George Washington Memorial Parkway. Pairwise comparisons among sites (uncorrected "p" = 0.7 -- 12.7%) and the nested Glade phylogeographic analysis suggested that hypotelminorheic habitats are fragmented. However, population subdivision (within site uncorrected "p" = 0 -- 13.06%) found at many of the sites suggests that hypotelminorheic habitats have a dynamic extent that fluctuates with the water table, forming temporary corridors between hypotelminorheics.