Gene flow in cave arthropods: a qualitative and quantitative approach.

Abstract

Slatkin's method (1981) for analyzing gene flow levels is applied to 11 species of cave arthropods. Patterns of gene flow are consistent with the dispersal abilities and the ecological requirements of each species. Troglobites in general have lower gene flow values than troglophiles or trogloxenes, but geology, vegetation profile, and geographic distance among populations are also important in determining gene flow levels. Gene flow patterns in Ptomaphagus hirtus, Neaphaenops t. tellkampfii and Hadenoecus subterraneus are compared. These species inhabit the same highly interconnected karst area in south-central Kentucky but differ in ecological requirements. Gene flow levels are more dependent upon the intrinsic characteristics of each species than upon the availability of routes for dispersal. Overall estimates of gene flow were coupled with a more detailed population-structure analysis in Speonomus delarouzeei, Hadenoecus cumberlandicus, H. subterraneus and Euhadenoecus puteanus. Results stress the need for this type of analysis for subdivided species, in which estimates of the average gene flow can produce misleading results. They also show how these types of measures are more relevant in describing historical patterns of gene exchange than in indicating current levels of gene flow. -from Author