Using molecular estimates of gene flow in a groundwater arthropod as a method to identify cross-gradient migration pathways in aquifers

Folsomia candida (Collembola) is a common soil arthropod that feeds on fungal particles and detritus.  It is often used as a bioindicator for soil toxins due to its close connection to the soil in which it is found.  Recently, F. candida has been described living in a shallow coastal Lake Michigan aquifer.  The extent to which these subterranean F. candida are able to move through pores in the soil was the focus of this study.  Individuals were collected from 12 wells located in a 1 x 0.85 km study area.  Genotyping of individuals using five Inter-Simple Sequence Repeat (ISSR) loci was conducted to determine the genetic relatedness of the populations collected from the twelve wells.  Populations from two sets of wells did not differ from one another based on pairwise F_ST values, while all other populations were significantly dissimilar.  The high level of genetic variation between wells suggests that transportation pathways between populations are very limited.