Genetic variation in a subterranean arthropod (Folsomia candida) as a method to identify low-permeability barriers in an aquifer

摘要

beendescribed living in a shallow (2.5-5.7 m below surface), unconsolidated aquifer insouthwestern Michigan. F. candida was haplotyped from 14 wells using inter-simplesequence repeats (ISSRs) markers, and genetic variation in F candida was used as abioindicator to identify pore scale to mesoscale migration barriers in the aquifer.With one exception, individual haplotypes were only found in single wells.A significant relationship was identified between interpopulation genetic differ-entiation and geographic distance, and F candida exhibits genetic populationstructuring over a very fine geographic scale (0.65 km2). Monmonier's algorithm wasused to identify two most likely subsurface barriers to migration. Hypothesizedbarriers divided the F candida populations into three genetically distinct groups,with two groups separated by only 15 m. These groupings are not dependent ongroundwater flow direction, and are supported by a minimum spanning network andAMOVA analysis. Because F candida movement is limited by pore size, these barriersidentify local areas of low permeability in the aquifer material. The study suggeststhat F candida may serve an important role in identifying geological characteristicsand patterns in aquifers that may be difficult to evaluate by other means.