Regular ArticleGenetic structure in a coastal dune spider (Geolycosa pikei) on Long Island, New York Barrier Islands

In this study, we analyse genetic structure among ten isolated populations of a sedentary burrowing wolf spider,Geolycosa pikei, collected from Long Island, New York barrier islands. Using allozyme electrophoresis to estimate gene frequencies at 12 loci, only four loci were polymorphic (i.e.Aat,Apk,Gpi,Idh-1), and populations showed little differentiation (meanFST=0.020). Contrary to stepping-stone model predictions, the matrix of genetic distances among sites was not significantly associated with the physical distance matrix, which suggests thatG. pikeion Long Island barriers does not adhere to a stepping-stone model.Geolycosa pikeimay be better dispersers than previously estimated and/or the ephemeral quality of the inlets may not allow for the development of significant inter-populational genetic differences. In addition, geologic evidence suggests that these barriers became relatively stable only 8000 BP. Therefore, these habitats have been only recently colonized, which may result in low genetic variability and inter-populational differentiation possibly due to genetic drift from repeated and prolonged bottlenecks during recolonization (i.e. founder events).